The AM Forum

Anybody know what instigated this?

http://www.youtube.be/watch?v=DeyXwdJQurU&feature=related

http://www.youtube.be/watch?v=sZ3vfTsHmC0&feature=related

http://www.youtube.be/watch?v=xnC1lUwhhQQ&feature=related

Looks like someone venting Passive/Aggressive.  Provides "evidence" for his case, but no data other than the vid and the rant.  No identifying information (call sign?) anywhere either.   Did have some good stuff on the Texoma AM Traders net though and some RFI vids on his site.  From some of the other vids, I think it may be a member here (former?).

I'm not going to zero in on any individulals, but you guys have no idea what kind of a mess we have down here in the 75 meter am window. You can't operate with 15 kc of many of these guys. We've got people trying to drive linear amplifiers running three of 811A's with 100 watt rigs. We've got people running Heathkit Warriers driven by 100 watt transmitters trying to run 400 watts of carrier. We've got out of control broadcast transmitters. One of the worst offenders runs a class E rig. These people have no idea what they're doing and resent anyone that tries to tell them. I gave up. You won't find me on 75 meters anymore. Any by the way-that's not my video.
Darrell, WA5VGO

The type of thing presented in the video has been an ongoing problem for a very long time.  Whoever posted those videos of WW9W probably lives very close to him.  Not to minimize anything but there is a guy in the same neighborhood that has been trying for year to get the WW9W to operate with lower poser to no avail.  He operates SSB exclusively and his "favorite" frequency is about 3.860 or so.

Darrell just posted the delimma here.  He and I have complained for years about several of them and they just laugh.  I have taken the step of contacting the ARRL OO but that hasn't helped.  There are several technical nincompoops in this part of the word and this is part of the reason I don't operate in that part of the band very much either.  You will find me there talking to an old friend before 6 PM and that is it.  My disclaimer to the video is I don't own a  video camera.

That third video tells it all.   The transmitter appears to have high frequency audio parasitics OR has some arcing going on somewhere between the modulator/final and the antenna.  To cover +- 100kc with that raspy side splatter is indicative of one or both of these problems. (Or caused by severe receiver overload if the receiver is located down the block and using a full antenna without attenuator - as mentioned later in this thread)

If it's really the transmitter, it can be cured with some careful troubleshooting.

I remember a time when I was in the 75 DX window working Europe.  Suddenly several guys broke in and said they could hear me up 35kc++.  I happened to look out the window and saw flashing in the sky as I talked. An antenna relay up on the tower was arcing causing a spark-gap transmitter effect... ;D  Nasty stuff.   I fixed it and everything went back to normal.


The bottom line is this AMer must be willing to admit there is a problem and start the troubleshooting process. Otherwise it will just continue in denial.  Most any well-working BC transmitter can be set up to run reasonably clean audio at +- 5kc... or it would not have passed FCC specs in the first place.


Heck, if I lived closer, I'd be more than happy to offer my skills to help him fix it.

T

Wonder if these guys have even been to Scranton.

There was a related thread (http://forums.qrz.com/showthread.php?326248-AM-Bandwidth) recently on another well-known ham radio forum. AMers complaining about splatter from other AMers.  Up to now, it has usually been slopbucketeers complaining about AMers. Of course, tune round the bands a little and you will hear slopbucketeers complaining about other slopbucketeers as well.

It may well be the case that some of the AM transmitters are not being operated according to good engineering practice, but sometimes it IS the receiver, or a personal vendetta between two operators. I have often been accused of being "40 kc/s wide" when I could not hear my own signal right in the shack on another receiver more than about 7 kc/s away from the carrier, and even less when I had the narrow low-pass filter that I use for congested conditions in line.

Once years ago I was told my signal was "buckshotting"; turned out I had a parasitic oscillation in the class-B modulator.  Cured it with a 100-ohm resistor in series with each modulator tube plate lead, right at the plate cap.  I take most such reports with a grain of salt, but usually do check out my signal on my own receiver to see if anything appears out of the ordinary.

But what concerns me is that some AMers are now openly airing dirty laundry on a public forum like YouTube, or on general amateur radio forums like Eham and QRZ.com.  This is inviting, even instigating, another round of anti-AM sentiment in the greater ham community, even to the point of a revival of petitions and docket proposals to eliminate AM or impose specific bandwidth limits. Those anti-AM attitudes seem to have somewhat dissipated in recent years, and the last thing we need is to have someone actively trying to revive them. Wouldn't it better to post such complaints on this and other AM-related bulletin boards and e-mail reflectors, where the alleged offenders, and not the greater amateur community, would be the first to hear them?

I do hear a lot of AMers on the air describe running impossible power levels from linear amplifiers and driving them with rigs running only 3 dB or so less power than the linear is claimed to be putting out. Sometimes there appears to be a complete lack of understanding about headroom requirements with low-level modulation.  Another one of my pet gripes is operating roundtables (or fast break-in) with stations scattered up and down the band instead of everyone zero-beat with each other.  This often makes it impossible or impractical to receive with the synchronous detector, and spreading about increases the over all total channel space occupied by a QSO.

OTOH, off-frequency operation may be due to the fact that some stations are running crystal control.  And sometimes with deliberate SSB interference, the "exit stage left" tactic is effective.

Regardless of the nature of the complaint against other AM operators, I see no point in getting on a high profile general-interest amateur radio forum to whine about it.

Maybe people just need to tell this person (and others) that they have a technical problem?

It's not like telling someone that they have bad breath...Or is it?

If several people were to tell me that I was 100 KC wide, I'd be all over it, what an embarrassment.

Has anyone told the supposed offender they have a problem rather than posting the videos? Has he responded or ignored it? Has he tried to fix it?

These people have been told repeatedly about the problem and it seems to make them ignore the complaints or worse, turn up the power or audio.  It is not as if several responsible hams haven't tried.  It is bad enough that I won't even talk to most of them.

One of them bought a couple of plug in SS replacements for 866s then wanted to return them because they wouldn't work.  Turns out he removed the jumper across pin 4 of both sockets and was getting output on only one of them.  That is the kind of mentality we are dealing with.

The video is from a guy within a city block of the station presented.  The receiver is overloaded badly, but the operator of the AM station is driving it much too hard and there is no telling if there is a problem in the transmitter or not.  I have dsicussed problems like this at a couple of hamfest and the operators just look the other way and try to make the "monkey swing" as they say.

That thread on QRZ has been locked. I guess they saw it was going nowhere and had enough?

I was surprised that toward the end, there was some positive input on the thread where some people wanted more information regarding AM.

I think the topic is too hot right now to start a positive thread to try to reach others who have an interest. 

look who started the whole thread. that may explain some things. :-\

Very well stated, although I don't think many people give a lot of creedance to Youtube anymore no do I think the FCC is going to be scanning YouTube for potential violators.

It's unfortunate that some people will not educate themselves about good engineering practice, but an email to the person "offending" should alert him/her to potential problems.

But like you, I don't think dirty laundry should be aired outside the family.

True, he never did explian how he was "bullied," but decided to use that word and that forum to complain.

As an addendum, why don't these YouTube policeman go around the band and record offending SSB operators who take up +,_ 15kc spectrum by running dirty or overdriven amps and not allowing enough headroom, or those ignorantly misusing those IHY equalizers?  

Phil

I can't watch videos but wow, am I glad I can operate 160 meters.

sounds like part of the problem is more appliance ops pushing the little AM button who don't know what they're doing.

Rob, we are talking BC transmitters and BC 610 type of stuff.

I don't think that would be a likely problem.  More like re-awakening the smouldering anti-AM sentiment that still exists in obscure spots within the mainstream amateur community.


So, exactly what do you think those guys are doing wrong?  I hear many BC-610s and converted broadcast rigs on the air that put out clean signals.  And in both the QRZ thread and in at least one of the YouTube videos, "Class E" operators are also cited as offenders.

Usually, it is not so much the frequency response of the audio admitted to the modulator that causes "splatter", as it is spurious distortion products. If my transmitter were putting out spurious trash, I would want to be told about it, and would then make an effort to correct the problem.

He seems to have it in for Robert in particular? ? ? Robert does have kind of a raspy voice with a lot of highs in it. It has been a few years since I worked him, but, IIRC his voice if he is not running any processing and an improperly adjusted transmitter could cause some serious splatter.

I remember one night, someone from here was running a '1-T and putting out "artifacts" all over the band untill I called him on the telephone to tell him. He made a few quick tweaks and all was well.

Maybe someone should call Robert and let him know about all of this so he can correct it before it festers too badly.  

But then the one who is doing all of the pissing and moaning might just be close enough to him to get a massive case of front end/IF overload??????????
But he isn't all that strong up here.

I washed my hands of this bunch a long time ago so I can't tell you Don.  I only know that if you were located where I am you would pitch a bitch about the poor quality signals.  I repeat, I have told all of them about their problems and they ignore anyone who says such.  From their point, they say the listening station doesn't know what they are doing.

Slab, you must have missed the part where I said the front end of the receiver is overloaded.  But since I am 120 miles away and have problems, it isn't all the complainer's receiver.

Guys there is no defending the operation of several of these guys.  They are not operating properly and could have mistuned equipment, have equipment with troubles or who knows.  They are a nuisance here and blank out any chance I have of talking to the MoKan group on 85 or the group on 75 in CO, Ne, and WY.

If the goal is to  prevent splatter, then a guy that owns such an expensive transmitter as a BC rig or BC-610 ought to make the investment in a bandscope setup. Its not a question of audio bandwidth, only splatter.

This may be one instance where the FCC should be brought in. I hate to be a rat but sometimes you need to make a move when all else fails!

I have visited a ham that was running a converted collins v20 and saw for myself huge peaks on his scope with NASTY FLAT WHITE LINES on the negative peaks.  Now I personally like the fella and he seemed very knowlegable about radio and has been a ham since before I was born.  I think these guys KNOW but just don't care.  It's a selfish philosophy.  They want to be LOUD.  It probably has to do with the 3.878 and 3.892 ssb groups that have been "at war" with AMers.  So they turn everything up and ignore the sidewinders.  Not everyone of the 5 land AMers are like this of course and quite a few do take a lot of pride in a clean strong signal.  I haven't been on 75 AM in over a year and I really miss it, but I will likely stay down below 3.700 when I return, except maybe for some early mornings when the signals are strong from coast to coast and the operators are more cognizant of clean operation.

well shoot i  operate down here and cant think of anything to piss or moan about. i hope i'm not one of the bad guys hahhaha

Nah Brandon, you're good to go.  You run a good clean signal.  It's potent and of course so some receivers might have some selectivity issues with it a little lol but that's not your fault. :)

That's the last thing we need. Seek out FeeCee intervention, and you just might get what you asked for, but not like what you get.


There are better and more effective ways to be "loud" than brute-force overmodulation.  Besides, that's a good way to blow a modulation transformer.


John, you have been conspicuous by your absence.  C'mon down to the vicinity of 3700 and below. There's been some good AM activity down there lately. We need more AM presence in other parts of the band.

Thanks Don.  That gives me more incentive to get something up in the air for 80 meters... a new girlfriend sorta waylayed my priorities (as they tend to do)... I've been working some 10 meters AM during the afternoons.  I'll get back on track soon! I'm moving to dayshift here at work, in fact this is my last "night",  so we'll see how that affects my radio schedule.

That's the sad part!!! The OO is a bunch of SH%T...They go for the easy stuff.
"You didn't identify in the 10 minute window" You were 1 kc into the Extra Class band". The OO 's probably do not understand the technical part of getting a radio signal on the air. Non-RF types. Or Appliance operators.
"She's a doin" kinda sounds like one of them good ole boys down South with a big mouth and that CB thinking......What is used to be with overmodulated wide audio in the CB channels.
Maybe the mod transformer will open up.........he probably has bypassed any overmod / over current protection in the TX and it will eventually cave in to the abuse.

The YouTuber posting must live very very close to see all that is going on. It could be his radio is overloaded........It's an expensive rig with a panadapter, and susceptible to overload.........Any one here monitor WW9W???

Jim,
      I never realized that this has become the festering boil that it has become.
I watched the first 2 videos and just assumed this was the usual slop bucketeers  pissing and moaning about AMers. We have had that same szht up here for some time with a few of the AMers just wiped it out for everyone. The infamous "Scranton Screwball", and K1MAN being prime examples. I have not been real active on the bands for the last couple of years, so I have missed all of this. (I used to listen a lot with the transmitter turned off)

It did get really bad up here in AM ghetto/window and I moved "down band" just to get away from it. The grousing, grumbling and infighting just got on my nerves. It is usually so much nicer down there. The big problem is that many of my buddies cant join us.

Whooping, hollering and carrying on can be a lot fun if it is all done in fun but...........
It really sucks when it is done with malice in ones heart. It is a shame that folks of a kindred spirit cant come together, and a few are hell-bent to screw it up for everyone else or just dont care about anyone else. Life is too short!!

I operate a converted broadcast transmitter and a couple of other large homebrew transmitters.  If I splatter (and probably have at times, unintentionally) I would hope someone would PM me or just outright tell me to "back it down alittle", not put it on YouTube as this has been done.  If  you will not identify yourself to me, then don't expect too much consideration on my part.

Constructive criticism is welcome anytime as most of the folks on this board know a heck of alot more than I can ever hope to learn about old time radio.  I think of it as a doing me a favor. 

Ditto!! I think we all feel the same way (at least I do). But.....................

With all of the pissing and moaning from the slopbucketeers that cozy up just a couple of Kc away from us and bitch about our interference or "being too wide", etc, it can have a tendancy to fall on deaf ears. Depending on where the complaints come from.
Sometimes you get tired of hearing it when you know your signal is clean.

FCC regulations treat differently the problem of "splatter" versus the use of high data rates (bandwidth).  The difference is often lost on the aggrieved parties.

"Splatter" is actionable under enforcement mechanisms that rely on technical standards.

High data rates, transmitted cleanly, without unwanted emissions, are a matter of operating coordination and cooperation with others nearby.  If interference is caused by incompatible modes and/or activity, the FCC relies first on operators to settle it.  Chronic cases can be investigated as malicious interference.

No licensee can have an expectation of complete protection against interference among the various un-channelized modes and activities we encounter.

Slab, this is not just a simple case of harassment that you routinely see.  We have the same stuff here, this is entirely different.  A couple of people who have trouble are using transmitters furnished by W0VMC.  As you know, he will set one properly as you can tell from hearing his signal on the air.  However some of those who have his converted equipment are splattering across 20-30 kc. 

Refer to Darrell's mention of the guy using a 100 watt transmitter to drive a Warrior amp.  That guy has a very deep voice and I have had an ongoing fight with him over the past 4-5 years.  At one time he had a McKie (sic?) Marine that he overdrove to the point I am suprised it survived.  He called me the frequency cop.  Another guy now owns the Mackie and he doesn't have the problem.   In the beginning I would call these guys on the phone to tell them and after several attempts I resorted to public pronouncements.  Nothing worked.  One of these guys told me he uses a specturm analyzer to set modulation precentage on AM.

The guy who posted the video lives so close to Robert that it would be impossible for both to operate 80 meters at the same time.  I know the guy has talked to Robert about it but don't know how Robert responded so I won't blame either party except to say they should get together and solve the problem.  Sometimes Robert does splatter but most of the time his signal is clear. 

Roy KB5MD has recycled BC equipment, his signal here is always very strong and is not a problem.  I don't know of anyone  in our area who has the problem that are subscribed to this board.   It is just that some blatently refuse to listen and fix the problem.  These guys operate mostly on 3.890 and I like to ocassionally talk to Jim, W0NKL or Ted, Ex-KC3OL, or Mike, K0ARA all on 3.885.  When the bunch is on 90 that is impossible so I don't work that part of the band any more and I live more than 100 miles from the people who are splattering.

well i will say this. you may feel that people do not take your advise on problems you see with their station. i also notice that some people do not take the common advise of if your a 5kc off of a 40 over signal what do you think is going to happen. 

don is 4 or 5 hundred miles from me, and i would think everyone would agree he has a clean signal and runs his stuff right. do you think there is any way i would fire up on 3.885 if he was on 3890 and try to talk so to someone? it would be silly on my part to even try. if i lived 100 miles from him i would figure it would even be harder. and that is with a grade a station. now take an average station and it woudl be even worse.

steve qix. he is what 1000 miles or more from me. same situation. about same sig little more freq response and a ton of audio power.

when i hear the guys in texas talking i will operate 5kc off of them sometimes but to me they are all talking pretty close in and i know that my signal will not be stronger then the ones they are working. they are a pretty small group and usualy dont work many piss weak stations trying to come in. so i do not feel i bother them. and just like roy said if i did all they would have to do is say someting and i would move or shut down for a while.

k1jj told me a year ago. if you put up a good antenna and have a good signal just to becarefull of who is around you. and try to be considerate of them.  and i try to do that but i'm sure like roy said i have took out some weaker stations when i have been on. to me it is just how it is and figure out a way to deal with it. or move where it is not so busy. i love the business of the am window. i dont want to call cq for 30 minutes but you have to take the good with the bad. that is just my take on it. but i am new to ham radio and dont know cw. so take it with a grain of salt.


and hope to hear you on john. we miss ya man. hahha

Not to diminish the importance of the matter at hand, but posting all three links here has done nothing to cure the problem and only helped raise the visibility and number of youtube views. We all know that 'fone is watched by numerous SSB troublemakers who have responded with jamming, or set up shop in places they'd not normally appear, when specific times and frequencies were posted in the past.

The youtube approach for airing complaints is no different than posting on QRZ or here. It's not a solution, merely a symptom of more AMers and hams in general choosing the internet for their communications and would appear to be more about being seen('heard') than finding solutions.

Interference caused by poor operating practices are a concern for all of us, but dealing with the specifics in online forums invites the attention we supposedly don't want. You can't object to folks airing their dirty laundry online, then turn around and air their dirty laundry online for them. If it's truly a concern, contact them directly. It's easy enough to mention 'a group of AMers' in the south, northeast or whatever else. I give Darrell and Jim credit for their attempts to deal with the problems offline. I'm not sure how asking online if anyone has contacted them trumps contacting them personally to ask if they're aware of the problem.

There's a good technical discussion to be had in this thread without repeating or otherwise including the issues that bring bad PR through higher visibility. If that's really a concern.

This is not a case of "my advice".  It is a case of misoperation, nothing more.  It is a case of not following good engineering practice.  Many people do but some of these guys don't.  That is the rub.  You may not have trouble but you may not be affected as others closer in are.  I hear stations all the time with the same power level at about the same distance, Roy, KB5MD and Mason K5YHX, that do not splatter over the signals of S-8 at my location that are on 3.885.  Now if they can do that, why can't the offenders?

yea i dont know man. my little point all i was trying to make was there are big signals on 75m. and we are all to close. yes some stations are wider then others and that is something that will always be. trying to change someone that will not change is simple to figure out. trying to get someone to understand that it is just part of it and not to let it bother them is just as hard to get across to people. its the same thing. ssb overmodulates and causes interfearance and so does a.m. signals. i see it everyday. i just move over enough or wait for a break in the action.

maybe after a few years it will bother me to. i dont know.

i'm just glad that its hard to put up a good antenna on 80m and usualy by the time someoen does there station is pretty clean and they practice good operating etiquette.

Maybe true, but I'd say the number of non-AMers and SSB troublemakers checking out links posted on this forum is minuscule compared to those seeing entire threads openly posted on QRZ.com and eHam. As for visibility on YouTube, this or anything else would have to be advertised elsewhere or you would have to do a search or stumble across it accidentally to find it, since it only amounted to a half-dozen or so out of jillions of YouTube videos posted every day. I suspect most AMers, including myself, were completely oblivious to this whole issue. I found out about it only when working someone on 75 in the wee hours of the other morning, who asked me if I knew what the hell was going on; he made it sound like a big deal. I don't see any reason for us to try to keep things like this hush-hush or under wraps from each other, whether over the air or on these forums; it would be in our interest for members of the AM community to be aware of what is going on. Those who would make it their mission to cause trouble would already be doing everything they could propagate it throughout the mainstream amateur radio community, regardless.

Regarding "splatter" and wide signals, remember that if your spurious emissions are 40 dB down, which last time I read the rules falls within the FCC specs of "good engineering practice", but your signal is coming in on someone's receiver 40 dB over S9, your garbage is still going to be at least S9 on that receiver, and that's only under the assumption that said receiver has a perfectly linear front end immune from cross-modulation and overload. On a typical Hammy Hambone receiver or transceiver, it's probably going to be much worse.

My guess is, Don, this is what happens in most cases. I know my Drake R4A's second mixer starts producing IMDs when a signal reads better than s9+30. I've looked at local strong signals on the Spectrum Analyzer, Agilent 7404A, that were clean with 5kHz response down 40db+ and the Drake made it appear they were splattering. Now ifn I were to call them out on it I'd be dead wrong.

That's not to say ALL matters are such. By the same token I see 20+ signals, both AM and SSB, that are truly 40kHz wide.

Having an SDR video done of our own signal is really are a good idea. Ya know how they recommend that men over fifty get a periodic colonoscopy test?  Well, same thing applies to rigs - we hams should get an SDR receiver test for our rigs at least once a year - especially when they are first built or acquired.

We need to find a ham who has a good SDR receiver and knows how to use it. Have him make a video. There's many out there these days. Be sure he is at least 10 miles away (or has a good attenuator) and can normalize our signal to S9+30 or so to see the weaker artifacts.   Look closely at the db down from the peak and the bandwidth while talking. Speech is a good way to generate the many combinations of IMD present.

We need to do it on the air so that the antennas are involved as well as simulating real rig conditions.  This includes RF in the audio, if present, which could cause splatter problems.


SSB:
 
I had some tests done a few years ago. Here is a sample done by SDR-expert Rob, W1AEX. It was done within a week after I built Dr. Love, my homebrew 20-75M linear amplifier. It was done on ssb, a great mode for linear amp tests and at full power output. Blow the screen up to full and look carefully at the 5kc horizontal marks and the 10db vertical marks.  Also notice how the signal drops off at the edges as it is tuned across. This is running audio limited to 3.0 khz.

http://www.youtube.com/watch?v=pkty-gwPXLA&feature=related


AM:

Here's Rob's test on my homebrew 4-1000A, plate modulated by a pair. Look closely at the bandwidth (5kc marks) and the db down from the peaks.  This was running audio limited to 5-6 khz.

http://www.youtube.com/watch?v=7Zd_NOIiSFo


Another solution is to get our own SDR receiver and keep it running in the receive mode. I've done this with my own system here. There are times when I switch rigs, like to the class E rig, and find I have the audio cranked up too high. This will show up immediately on the SDR as excessive bandwidth but NOT on the scope or audio monitor unless you have exceptional sensing abilities. This is because we may be limiting the audio negative peaks, but exceeding the capability of the modulator or final's ability to produce higher audio peaks. IMD can be sneaky in that non-linear operation is hard to detect except for seeing the end result in bandwidth.

The best part about checking our rigs is the confidence we get when plopping down near another QSO. We know exactly how to run our rig so that it does not cause excessive side chatter to our neighbors.  In contrast, if we operate blindly, the only way to know is to unkey and see if they are complaining about us down the band... ;D

T

Is this a receiver selectivity problem? My current AM receiver is so wide I cannot work say 3.880 if the east coast guys are running on 3.875. My QSO's have to have at least 10 khz separation from an adjoing QSO, but it's not the transmitters, but rather my receiver bandwidth and proximities to stations.

Phil - AC0OB

There's a particular guy in Maine that is the reason that I've never been on 3885 phone. His carrier is 20 over 9 on my Beverage here in SW Missouri. I simply cannot fathom how anyone could have a signal as wide as he does. About every time I think about joining the AM group around that freq, he comes on and wipes out 75 meters for well over 30 KHz. (And no, it's not receiver overload).

I discussed this with another guy, and it turns out that yes, he's been told but refuses to do anything. I don't know if he's one of the guys being discussed in this thread or not.

When a signal is only of modest strength, you switch in a 500 cycle filter, and you hear spitting 15 kc away, it's not a receiver problem.

A major problem around here is guys that have no idea what their doing try to run "linear" amplifiers on am. They want to tune it just like they do on ssb-turn all the knobs for maximum output and let it rip. If you tell them their splattering they tell you your wrong. If you try to explain how they should tune the amplifier, they say your crazy. You wouldn't believe how many guys are trying to drive four 811A's with a 100 watt transmitter. You can't convince them it's a wash if they tune it properly. It's hopeless.

73,
Darrell, WA5VGO

Oh, it's certainly more than 15 KHz away! I have some notes somewhere, but if I recall he was at least 37 KHz wide.

And for the record, his bandwidth did not decrease even after we switched in >20 dB of attenuation which reduced his carrier below S9.

That's not entirely true, Darrell. If the signal you're tuning across is sufficiently strong enough to create IMD products in your receiver they will sow up thru any filter 15kHz away.
That example is similar to the guy that told be my carrier was 4 kHz wide. 

That is the reason I use an attenuator Bud.

I have been following this thread and looking at the YouTube vids. And I wonder how we can analyze what is going on in the TX to make it so dam bad??
Wouldn't there be any overloads if the final is not tuned properly or the final not neutralized if using triodes??? On this 80M freq. Many BC TX's don't like 80M or 40 because of the longer wires in the harnesses, etc.
Would this splatter be caused from excessive modulation?? How would the TX sustain this type of operation without damage to the mod transformer?? Would the overloads be bypassed to allow this misuse??
The panadapter display, looks like a lot of audio energy in the mid to high freqs.
The basic audio sounds unusually clear through on YouTube. Any sibilance (S and H) drives the TX bonkers. Creating wideband audio.
But knowing CB technology they like to see the meters on anything pegging and everything set for max.
Oh well
Fred

In my Gates BC1-T, the rf lead from the shielded oscillator/buffer box to the grids of the parallel 807 driver stage was an unshielded wire embedding in the wiring harness along with the DC, audio and filament lines.  That caused all kinds of squirreliness even on 160m.  I replaced that wire with a BNC connector, and the 807 grids are now fed with a short piece of RG-59.  That made the 807 stage a lot more stable; 807s are squirrely enough under the best of conditions.

The BTA-1R I parted out had some long leads between components in the output stage. Like 18" or more, and unshielded to boot.  Looks like they just set the components on the chassis where they saw fit, and used whatever length of wire it took to connect them into the circuit, more like the type of construction one would use for an audio amplifier. That's probably OK for the AM broadcast band, but by the time you get to the amateur frequencies, even 160m, those lead lengths are a little excessive, and could contribute to all kinds of parasitics that could make the signal trashy.  If you are going to use one of those transmitters on anything higher than 2 mc/s, you are probably better off completely stripping the rf section, and starting over from scratch using the same tubes and as many of the original components as possible, but using a more typical layout like that seen in homebrew transmitter design.

All these guys with bc rigs have to do if they want to be LOUD is get themselves some kind of AM broadcast peak limiter.  An old CRL PMC model, inovonics 222, BL Modulimiter, DAP310, Texar...any of those will work.   Some show up on eBay; I've seen them at fests...get it set up right as the last thing before the rig and drive it with a 528 voice processor or some other mic box and any of them will be loud without clipping and therefore, a lot cleaner. 

SplatterMaster ----  I'm begining to like the name.... ..

klc

Fred whoever posted this is using a PRO 1,2 or 3 with only  6 db attenuation.  They are so close to Robert that they probably could remove the antenna and still have gross overload. 

Tom

I use a Bird 4273 sampler (rated at 5 KW) in conjunction with  a combination of Weinschel power attenuators directly connected to my Flex 1500 for precisely this type of test.  I then absolutely know what my splatter factor is.

I took my 1500 to demonstrate it to a friend who has a modest lab and we both were impressed to see that the power calibration of that little animal is very accurate.  It truly does serve as a spectrum analyzer when properly hooked up.  The key to any of these type of checks to is to have a good sampler and attenuate the signal down to a level that your instrument can handle without overload.

After looking at some representations of "splatter masters," I'm convinced that it is not a simple matter of overmodulation but rather parasitics.  One of the representations was viewed on an Agilent spectrum analyzer and the operator was careful to set the input attenuator to avoid overload, so the splatter was real in my view. Be sure to expand the operator's commends below the screen

http://www.youtube.com/watch?v=Si6WcSvO-Sg

http://www.youtube.com/watch?NR=1&v=AVMkP7gHJII&feature=endscreen

Keeping our transmitters operating with good engineering practice make sense not only from a "good neighbor" point of view but from an economic point of view - less blowing up of mod irons

Al

That’s the problem! It's not people who run too much audio or don’t know or care about what they're doing; it’s the proliferation of SDR out there. Stomp out SDR radios and nobody will notice, well maybe. I started in Ham radio back when everything was already SSB and have to wonder what it must have been like back in the forties, fifties and sixties when everyone ran AM? Would think that splatter was everywhere along with heterodynes and the like. I kind of like to listen to 7.290 and have been amazed by the amounts of heterodynes form other stations on frequency at times. Have only heard this once or twice on 1.885 and I am just not proficient enough operator to work eighty so I avoid that band. But have to wonder if things were not a lot worse back in the old days? Maybe because the radios and things like SDR are so much better we notice this stuff more?

And many, back in the "good old days", had crappy receivers (compared to today's modern marvels) but we all survived on AM. Most AM off the shelf transmitters were tailored to 6 KHz bandwidth. It was always fun operating Field Day during the late 50's and early 60's on AM. Lots of beer, and after awhile, you didn't even notice the heterodynes.

And, on several of those videos where the video camera panned the front panel of the 756 PRO II, it looks like the Noise Blanker is engaged (button light is on). The 756 PRO series are cool receivers but they're not high quality spectrum analyzers.

"Back in the day" all there seemed to be was table top transmitters and a desk KW, here and there. The well appointed station might have Collins RX/TX. There were folks who really knew electronics cuz they had to draw schematics of circuits asked in the FCC test.
The bands were full of hetrodynes. There was a good Ham friend of mine that was around when the change was taking place to SSB and he was so happy that AM was going by the wayside. I don't think that the CB mentality was rampant as it is now.

Fred

Let it be said that it's not an easy task to build or modify an old rig - or even get a commercial rig to be clean.  There are many adjustments involved and it doesn't take more than one incorrectly set to cause excessive splatter.  Even picking the wrong tube for the job or using incorrect parts is enough to make it a struggle.

For example, it took me about 10 years of experimenting with various homebrew and commercial linear amplifiers before I finally found a combination that was clean enough to run in the DX window without complaints.  There are nights when the noise level is S3 and the locals are S9+40 over.  If we even run a rig that has an acceptable 3rd IMD at -30db down, our SSB splatter may still be S9+10  3-4 kc up the band. Thus a rig that is not at least this clean will cause problems.

Now, on AM, we have normal bandwidth that is wider, like 4-6khz audio and more. (8-12khz total bandwidth)   This makes the problem of running a clean rig even more important since we co-exist with ssb stations that have their own ~3kc spacing standards.  

My hat's off to the guys on the band who figure out what it takes to run a clean QRO rig.  It doesn't matter if we are running SSB or AM through a linear, the IMD will be roughly the same. At times I've heard some exceptionally clean ssb rigs that were S9+50 over and they barely had side chatter 3.5kc away. I will sometimes break in and axe them what kind of amplifier they are running and compliment them on the cleanliness. Heck, I want to know how they pull it off.   A fast way to tell a clean amp is to listen on the opposite sideband. (both TX and RX on ssb) If we hear barely any audio, the amplifier is probably clean. If there are problems, the audio on the opposite side may be down only 20db. This assumes the exciter has good opp sideband suppression.

Jay/W1VD brought up a good point in another thread - if we reduce our power output by 3db, the IMD products improve by about 9db. This is tremendous!  The same applies to AM. If we stress our modulators and final by 3db less, (1/2 power) they may have the headroom and final amplifier capability and linearity to do better, in many cases.

Also, backing down the audio to -90% negative and  115% positive maximum with the audio rolled off to 4.5khz can do wonders if the rig is acting linearly in the first place.  

As Al/VTP said, the final check is to have a buddy analyze our rig on an SDR receiver and video tape it too.

Again, it's NOT an easy task to get an overall station system to be clean.  Being that many of us are not industry professionals, I'm surprised there are not more problems like this on the air.   It hurts all AMers when a few are having problems getting their rigs ironed out.  Let's help each other when we can and over time the situation will improve.

T

Will try to keep this on topic, but to answer some questions raised, here goes:

- Yes, back in  the last century, specifically during the '50's and '60's, the bands were full of heterodynes. We just learned to live with them. As for splatter, someone would generally break in and tell you, and you would turn down the audio gain. It happened to me while running high level negative cycle loading, and I thanked whoever told me. I had no test equipment, and depended upon others to tell me if I was OK or not.

- I spent a good part of my career testing amplifiers for distortion: two tone intermod, linearity, group delay, etc. Every type of amplifier is a little different, but I came to the conclusion that if you wanted to operate in the linear region, you needed to back off at least 6dB from saturation, and preferably 10dB.

Translated to ham terms, if you have a linear amp capable of 1KW saturated output on CW, for clean AM linear service you need to run it at no more than 100W output. If you already have a 100W output plate modulated transmitter, a 1KW linear won't buy you a thing. You can push it to 250W output, but you will generate noticeable distortion products. In essence, you are trying to amplify three signals, the carrier and two sidebands.

I realize that this discussion does not apply to the plate modulated transmitter that is the subject of this thread, but  these items were brought up along the way.

73, Jim

No, the flavor was anti-CB, and CBers were considered "riff-raff". It was after the technical testing standards were dumbed down that the "CB" problem began.

I think your right Don. I was thinking that the FCC would be there to help repair the problem and help the poor ham guy out? What was I smoking that night?? ;D ;D

Tom & others

Comments well taken.  We are all engineers, by avocation.  We are supposed to be running stations using good engineering practice as per part 97.  I

Al

Im using an old military directional coupler that has LC connectors so its obviously for a bit more than exciter power. Ive run 5KW thru it and into several high power attenuators for IMD testing into the SA.

I should just wind a big toroid!

Carl

And I've never heard Carl splatter either.

Very true, but unfortunately, those of us in the AM community who build, restore and convert our own transmitters are but a tiny minority of the Hammy Hambone community-at-large.  To-day, most hams set up their station by credit card, not by Handbooks and engineering texts. Hell, it is not unusual to see postings on the various amateur radio forums by Extra Class licensees, asking for instructions on how to put together a simple coax-fed half wave dipole, or else asking where they can buy one ready-made.

As far as I know, none of the major ham equipment manufacturers any longer produce a modulation monitoring scope capable of viewing envelope and trapezoid patterns.  The big ones, like Yaesu, Kenwood and even Heathkit used to offer monitor scopes custom made to go with their transceiver/leen-yar lines, but evidently quit producing them due to lack of customer demand.  It most likely reached a point that not many of their customers knew how to interpret scope readings, so why would they want to purchase one?.

I might add, a waterfall or pan-adaptor display on a transceiver is not the same thing as spectrum analysis using a precision measuring instrument. I believe such equipment is readily available at not too great a cost, in the form of a black box that attaches to the rf sampler and uses an external computer with accessible video card to produce the display.

You'd have to hear him to hear him splatter.

I think dr. Tron is taking appointments in the am window over the next few weeks if anyone needs a transmitter checkup.

It might also imply that their equipment might need one if it was an additional accessory.

Of course, if you don't read the instruction/operating manual first to understand the features, functions, and specifications of any particular new "high-tech" wizzy rig, the chance of screwing up something on transmit or receive is probably quite high.

 

EVERY rig needs one.  To make sure the signal is not flat-topping on positive peaks.  On AM, to make sure negative peak modulation doesn't exceed 100%. To show if anything unusual is occurring with the signal.

Weird distortion (like parasitics) may show up readily visible on the envelope pattern. I couldn't count the number of times I first discovered something wrong with my signal when I noticed that the scope pattern had taken a turn towards the abnormal.

Operating a phone rig without a monitor scope is like driving a car at night with the headlights turned off.

Don, sadly, a lot of people who operate AM with high power cannot interprete what they see on a scope.  I don't recall any questions about reading a scope on any of the tests.  I haven't looked in a long while but don't remember any.   About the only people I know that can read one accurately participate in AM or CW modes and build or repair their own equipment.  As you know there are people out there who work on equipment and don't have a scope.  Most of them are just parts changers.

There are other long time hams who have never seen a scope and wouldn't know how to read it either as I mentioned earlier, I know of a guy who works on equipment and says he uses a spectrum analyzer to set modulation percentage. 

Jim,

A sad commentary indeed on the technical caliber and expertise of many radio amateurs nowadays.

73,

Bruce

I went to great lengths to make sure my Rig does not do that.  The comments about robert are just crazy.  In the end, its up to the operator to feed any transmitter, Roberts or a BC rig with the correct audio gear to filter it. If you run full audio you get wide audio through either type of rig.  In fact, Robert always told me to never go past 7KC period and the right gear is needed ahead of the rig.

The one thing I will point out as have others is the front end overload. That icom wont take this at ALL.  I have that icom sitting here.  If that man would put in some ATT and back it down, he would not hear the Am'r at all. If you hit that icom with any kind of big signal, Its splatter city.

C

Should read;

"If you hit that icom with any kind of big signal, Its splatter IMD city. "

Sorry C, I'm in a picky mood today. Nothing personal!

Good point, Buddly. Using the word "splatter" invariably points at the transmitter, when it could be intermod at the receiver.

There is a tendency among people who complain to blame our "old gear" before fully exploring whether their "new" receiver could be vulnerable to problems, either by its design or by mis-adjustment.

There was a guy in NJ who used to beat up on us when there was an AM QSO around 3825Kc. This was before the FCC reapportioned the phone band, so a few years ago now.

He was convinced we were "splattering," and aimed most of his bile at me in particular.  I went through and checked things like neutralization, my grid drive, and other parameters where problems might not show up on the 'scope, because I knew I wasn't hitting baseline on modulation peaks.

No problems found.

It was then that I approached a well-known Dog X-Ray operator who has published a number of papers and has a website with equipment reviews.  I said I had received multiple complaints from one person, and asked whether he could explain to me the potential risk of receiver problems, if, for example, the noise blanker or pre-amp were selected when encountering a strong signal.  

I deliberately did NOT disclose what mode I was on.

I got a nice discussion of how, indeed, a receiver could be the problem, and he even named a few brands and models known to be particularly vulnerable.  He followed up by asking about my setup, and it was then that the entire tone of the conversation changed to one of presuming my "old gear" on AM was far more likely to blame than any modern transceiver.

I had gotten my answer (the first part), and left it there.

The Yeasu 1000D was a monster for this until someone figured out the filter switching diodes needed to be PINs. Once changed over the receiver really perks up.
The 1000MP has similar problems and with so many in the field you're bound to excite one sooner or later.

Moving targets are hard to hit ::)  However Ive had my share of reports especially when using a new rig and the monitors are on other benches/rigs. The best monitors are the guys complaining or those I ask to listen 8)

With AM capability from 160 to 2M it gets hard to remember all the best settings.

On usually works.

The hams most motivated to be "kilocycle cops" are generally those least suited for the position.   Pseudo spectrum analyzers built into modern gear and adopted by the technologically challenged have not helped the situation.

I agree, but that wasn't the point. I was merely responding to your statement, "none of the major ham equipment manufacturers any longer produce a modulation monitoring scope capable of viewing envelope and trapezoid patterns". I also suspect that AM isn't high on the list of operational concerns for the major equipment manufacturers. And, even it there was, the challenges of interpreting the transmitted waveforms may not be within every ham's grasp. For those that can grasp the value of a monitor scope, a trip to a flea market and for $5 or so, one can generally acquire a scope suitable for transmitter output monitoring.

The scope is just as useful for monitoring SSB as it is for AM.  Remember the famous "Christmas Tree" pattern that at least used to be depicted in the ARRL handbook, to show what a clean SSB signal should look like?  I'd bet there would be a lot less splatter from over-driven SSB linears and other mis-adjustments if more slopbucketeers used a monitor scope and knew how to interpret the envelope pattern.

Most of us here probably agree that a monitor scope to monitor the transmitted waveform, regardless of the mode, is a good thing. But again, your statement, "none of the major ham equipment manufacturers any longer produce a modulation monitoring scope capable of viewing envelope and trapezoid patterns". Why would a current manufacturer spend the design and manufacturing dollars to develop a monitor scope to monitor transmitted output today when their advertised transceiver hype claims great specs for transmitted output of their rigs? Whether they're all true or not or if it's just operator screw up, it makes no sense to me for them to offer a monitor scope product that might show their transceivers not functioning per their specs regardless of the reason(s).

they should offer such a product if they make and sell a complete line i.e. rig and rf power amp because the amp can be improperly operated or overdriven.  for example both yaesu and icom make s.s. amps to go with their rigs (or used to, I assume they still do) and a monitor scope is needed because those s.s. amps especially can be turned into real grunge factories when overdriven.

But could you expect those Hammy Hambones who have managed to pass the Extra Class test, but who cannot decipher the elementary instructions in the Handbook on how to assemble a half-wave coax-fed dipole, so they post on-line seeking someone to explain exactly how to do it, to be able to interpret the envelope pattern as displayed on a scope?

More likely, the reason the major appliance manufacturers no longer offer a monitor scope in their product line is that there wasn't enough demand for them. If enough customers were willing to pay money for a scope, you could rest assured that Yaecomwood would offer them for sale.

Otherwise, why doesn't some after-market manufacturer offer a universal monitor scope, something on the order of the Heathkit HO-10 (but hopefully better quality), or the YO-100 (http://foxtango.org/ft101/YO-100%20YO-101.htm)? (Maybe they do, but I haven't noticed any ads lately for such a product).

Would a single-purpose, low production quantity, scope be economically feasible?  I doubt it.  Better off buying a run-of-the-mill, general purpose oscilloscope and dedicate it to modulation waveform monitoring.  

I see relatively modern, functional oscilloscopes available on the used market these days for under $100.  I bought one myself this past October for $55 at the Hall of Science hamfest.  

If someone wanted a smaller footprint scope, the trend now is to portable LCD display models.  But they are more pricey.

Eric

The plain truth is, you couldn't compete with the inexpensive analog scopes that are being dumped onto the used equipment market now with a dedicated monitor.  I have two decent scopes which I got for $0 because they were analog and considered obsolete. They also only got to 50 or  60Mhz which is pretty low.   Industry is only buying the new PC based Digital Ghz range scopes, and few are paying to repair analog jobs.

Now, getting operators to actually learn how to use those scopes?  Whole nother animal. 

Remember lissajous figures?  A scope and low voltage AC signal and you can diagnose componets right in the circuit.  I learned to evaluate diodes that way. 

I have heard complaints that the new PC based Digital Ghz range scopes scopes don't always display all waveforms correctly. A hamfest bargain might actually work better. And I am aware that "digital" and LCD don't necessarily mean the same thing. But if CRT TVs and computer monitors have become obsolete, no doubt the same thing applies to oscilloscopes.

Many of us buy used radios and components at a fraction of the original price, but that is not to say that everyone who would want a monitor scope would go the $50 used hamfest bargain route.  Those who fork over $10 grand for a transceiver probably wouldn't be all that concerned about the price of a quality, state-of-the-fart monitor scope. And if enough of the hams who need to use a monitor scope actually purchased one, it wouldn't be a low production quantity item, any more than an accessory like an antenna tuner.

I did go the cheap route myself.  With a Heathkit HO-10 for $30 at a hamfest.  Spent a few hours getting it to work right, and then modifying out some of the original design flaws, like a focus problem and internal 60~ hum that not only affected the X and Y axis, but the Z axis (brightness) as well.  The manual says the hum is inherent to the design, but "shouldn't" be a problem given the purpose of the scope - modulation monitoring. I was able to clean it up with a little effort, so I know the Heath engineers could have done the same, but just didn't want to bother.  Since I purchased the original one, I have picked up 3 more basket cases for little or nothing for spare parts and spare CRTs, which like everything else, appear to be turning to unobtanium. I have already had to swap out the power transformer with one of the spares.

Things sure have changed, haven't they? QST and the Handbooks used to regularly feature monitor scope construction articles. I remember sitting in high school study hall around 1969 tracing the schematics for one of those articles.

To see the Slattermaster in all of his glory you would need a spectrum analyzer OR Panadapter type display to see a wide signal and distortion products when the higher emphasized freqs are transmitted.
I bet this guy is using an FM limiter with the 75 microsecond pre-emphasis. And killing that poor BC TX.
Fred

You can get a HP-141T system with the 110mc plug-in for $250 or less these days in working condition. All discretes and easy to work on, usually just needs caps and a few resistors. The only hard part to find is the CRT.

Back in the late 90's HP was offering tremendous trade in deals on them for the latest and greatest. The Test Equipment manager at work swapped me all good modules and mainframes for hamfest junkers since HP was just going to destroy them. I wound up with 4 complete systems with lots of the extras. Sold off 3 when I got a chance at a later model and moved the other over to the ham operating section and later picked up a couple of dead Kenwood station monitors and fixed those.

A 40MHZ dual trace Leader can be found for $20 and a 50MHz Tek 453A for not much more if you just want to look at waveforms but as Fred mentioned it doesnt tell you much except to get in the ballpark.

The old Hallicrafters SP-44 Panadaptor is good on a 455kc IF before any filtering and I use one on 10M to spot carriers during openings.

I don't see what the big deal is on making a mod scope.  Had an old Heath O-10 scope given to me a few years ago because it "didn't work".  Replaced the fuse and it worked as good as it could considering its age.  Never could get the vertical centering control to center the dot, so pulled the vertical amp tubes and replaced 1 way out of range resistor and it centered itself.  Just used 2 caps to couple the RF from a homebrew 'tuner' to the vertical plates.  Ran the audio into the horizontal front panel input.  Works fine.  Cost me nothing except junk box parts.

I will have to agree that there are those with licenses that can't change mikes or fuses without help.  Guess I've learned a few things over the years;  especially since I hate to spend money when I have all the parts, more or less, to build it.

For the same reason they came up with waterfall and panadaptor displays. They're fun to look at, even for idiots.

We don't need more regs but it it were required that every commercially sold 'ham' rf amplifier incorporate at least a 3" CRT based monitoring scope, it would help a lot to educate even the most ignorant of hams including those who are merely attracted to shiny objects.

By default the thing would be "on" with the beam biased off except during transmit and then on TX, showing the RF waveform against a 15-120Hz sweep. (for the cheap seats, just derive 3-4x overscan from transformer secondary as is done in the Catalyzer et. al.)

It is a small increase in manufacturing cost IIAR 3" flat-face CRT with P1 or P2 phosphor are still made with decently low V/inch deflection sensitivity and cost about $100 retail.

High voltage is already present except for SS amps (where the crazy-high cost of the amp would further minimize the cost impact of a 2-3KV 2mA supply), and $10 worth of extra parts would do the job.

For fussy folks, a dynamic focus voltage is easily implemented with passives so that the beam is sharp in center and edge.

Balanced drive to the plates is also in order but that is a little extra cost. Unbalanced drive can result in slight defocusing.

All adjustments could be internal as there is little need for user alignment if operating voltages are steady. There's plenty of plastic in today's amps so there's a place to mount any pots etc. that might be at HV.

Think of it as a feature, and the better amps might have real front-panel scope features like front panel centering, focus, intensity, astigmatism, rotation adjustment, external connections for RX IF monitoring (small broadband amp for driving the vertical plates), and other pretty stuff.

CRTs do not change V/in sensitivity much over their lifetime and it depends almost completely on accelerating voltage so the scope could also be factory-calibrated to indicate max. peak or carrier (RTTY and CW) power within 5-10% and no front panel controls are really needed. A nice graticule with a traditional zero, 50%, and 100% line for hammy alignment of carrier and observation of PEP.

Trace intensification at flat topping and at >100% negative modulation would be a plus and can be done with passives.

I'd like to say make it impossible to turn off the scope, but someone who likes to sit in the dark would dislike that because of the relative brightness. A brightness pot would be a minimum necessary control. (BTW cutting heater volts in a CRT is a sorry way to turn it off because it can strip the cathode, but the costly old IC-9000 does it that way)

The reason I say CRT and wrote all that good stuff is that a cheap LCD updates at a fixed rate as a fact of its design and requires costly a-d conversion and what amounts to another processor to make it work, and further does not have enough 'points' to avoid aliasing the RF signal so that means downconversion and more proicessing to create a 'fake' evelop that is a copy of what is coming in. A LCD having a fixed update can only accept sub-harmonics of the update frequency. Typical TV set LCD at 30Hz, would give only usable 30, 15Hz, and 10Hz sweep rates.

And LCD scopes besides cost are unpleasant:
http://amfone.net/Amforum/index.php?topic=27948.0


Force hammy hambones to have scopes in their amplifiers!! - I am so mean.. But it would educate them right away, and in their faces, how to adjust and drive them. Its one thing to blow and go, but if the scope is right there scolding you each time you throw a mess onto the air it is pretty damning.

Sorry, no solution yet for those running modulated amplifiers. One problem at a time.

I have a $100 spectrum analyzer and you can too. Its called a Soft66LC2.  It costs about Cnote, Plugs into the computer and with a small wire antenna laying on the table, you get a fantstic output scope.  It also makes nice reciever.  lDepending on your computer you will get 200KC wide.  100 up and 100 down of center freq.  I get about 120 on my laptop.

I monitored my big TX's signal the other night. Nothing new here.. Close that base line on my Oscope and there she goes, big time wide.   Back it off to 80 negative max, set peak limiter there, 10 KC wide. No splat. 

I am over the super hifi sound.  I backed the high cutoff way down and narrowed things up 6 months ago. I just want a nice clear TX with some punch.

C

I had to replace the HV filter cap.  They seem to go out a lot.  Don't remember the exact value, but it's rated at  something  like 1 kv at a fraction of a mfd. That took care of the z-axis (brightness) hum modulation.  I got rid of most of the X-Y axis hum by replacing the piece of scrap tin Heapshit had wrapped round the neck of the CRT with a real black metallic CRT shield salvaged from some old piece of surplus equipment I had scrapped. Then re-routed the filament line, using a wire lead for both sides of the filament line instead of using chassis for ground return. Pulled out the vertical amp tube and the slopbucket two-tone test generator, to save wear and tear on the power transformer, which also has a reputation for crapping out (I have already gone through one).  I also made some mods to the focussing circuitry and astigmatism adjustment, so that I get a fine dot on the screen instead of a fuzzy blob.  It's a pretty good monitor scope now.  I plan to try balanced rf feed to the vertical plates to see if that cures the skewed display pattern.

I remember that thread (http://amfone.net/Amforum/index.php?topic=27948.0) now; that's where I heard it mentioned about digital scopes sucking for modulation monitoring.

FYI: Heathkit made an O-10 oscilloscope; you have a HO-10 monitor scope

(http://www.radiomuseum.org/images/radio/heathkit/laboratory_oscilloscope_o_10_485568.jpg)  (http://eshop1.chem.buffalo.edu/images/Heathkit/HO-10.JPG)

I think the addition of any type of  'scope to many Ham ops would be another hurdle to understand the display.
It would be eye candy and the more mis-adjusted the TX the prettier display.

I pulled caps out of a derelict HP scope I got somewhere (junk swap?) and put them in sb610.  I run the 610 off buck transformer like any older tube gear--hope that preserves p.s. transformer.   the heath monitor scopes got worse with time instead of better.  the CRT screen area seems to have gotten smaller.  with the SB614 the CRT screen is so tiny the 614 is useless to me.  IIRC that h.v. filter cap in the 610 (and I think also the HO-10) is 1.6 KV and .1 uF.  Another thing I did was not run the RF through the 610 but rather through a T connector with the vertical part of the T connected to the 610 and the RF through the top of the T to the antenna.  Seems to work just as well.  

I heard that at the last Hamvention there was some outfit selling these Chinese flat screen scopes, brand new with all kinds of modern high tech digywigy features for around $200 each.   I saw one at a friend's shack, Greg WB9DNZ, and it looked real nice, small and lightweight but $200 still too much for me.

The SB-614 really uses a 3" tube but wastes some of it by using a smallish escutcheon to make the screen look rectangular. Kind of stupid but I guess they wanted that modern look. They could have used a 4MP1 rectangular tube but it cost more than the 3RP1 they had been using. The SB-614 uses balanced deflection for RF and sweep. It also has the trapezoid 'generator' form of amplifier linearity indication that some people don't like.

The SB-614 is a little on the complex end but I agree that basic mod scopes are simple. What percentage of hams can even make something that simple? Lots of hams would have trouble making a 12V power supply. For them a brand new $200 mod scope is a good deal.

Its likely 5" CRTs are no longer made and that is a pity because the patterns are much easier to see at a distance meaning the monitor does not have to occupy high value space right in front of the operator.

Nobody will spend the money on them until there is once again a threat of being busted for technical violations.

I can't imagine operating the station without the reassuring green glow of the Tek 323 scope sitting on top of the R-390. And the scope was free, all I had to do was replace a power supply filter cap.

Which brings up a question..What is the best English word to say when looking at a modulation envelope in order to keep the display in sync? Mmmmm?

Bill

If you are referring to that pseudo-trapezoid pattern whose audio source is derived from rectification of the rf signal that is fed into the scope, it does indicate amplifier linearity: the linearity of the vertical  and horizontal amplifiers in the scope.  Useless for checking modulation linearity of the modulated stage. It accurately indicates percentage of modulation, but so does the regular envelope pattern.

3" CRT's were in the CE 100/200V, Cosmophones and maybe others.

Heath and Kenwood made lots of station monitors and they still sell for big bucks on the used market.

I dont see it a big deal to add a SS CRT in modern rigs or sell as an outboard option. For the idiots (90+% of current hams) have a bell go off when things are set incorrectly and make it impossible to disable ;D

I have a NOS CRT for a Tektronix 500-series scope.

PM or email me.

Real scopes have square screens Paul! I paid 20 bucks for this Tek 485 and got a clean Tek 453 from a neighbor for free. Life is good!

A scope is not needed to indicate linearity. A simple red/green light could show when something is being driven too hard. This would make more sense for the mass produced transceivers. Given most, if not all new rigs are DSP based in one manner or another, all this could be done with the DSP.

The vertical and horizontal amplifiers in any good scope (ones you can buy for $50-100 at most fests) will be linear, especially at audio frequencies. The SB-614 and the Hohos are junk and should not be used for this or any other waveform monitoring.

CE 100V/200V's used a 2 inch scope (2AP1).

Like that RCA audio processor Gary/INR had:  "Normal," and "EXCESSIVE" with a row of LEDs to show how hard he was hittin' it.

Exactly!

I just use a 1kHz tone generated in the Shure SE30 mixer, Bill.
Pickup an old audio/function generator and have at it!

A trap pattern would be good I guess.  But a normal modulation scope is not going to show splatter. I guess at the very least, you could monitor your signal on a seperate receiver and roll the vfo around.  

In todays day an age, You can also just ask a guy with receiver and spec display to give you a Screen shot of your modulated rig.  


C

ROB, ouch!!!!
That display looks familiar. Like an over modulated Ranger TX. Squared off audio and those big spaces of cut-off carrier.

Nice bright display..........love these, once high dollar, cheap 'scopes.

Somewhere round here, I have a 1" scope tube.  IIRC, it has an RCA 900-somethig number.  Looks like a metal 6L6 with the top of the envelope made of of glass, which is actually the CRT screen.

I have a couple of those 1" CRT's; one in a National scope and another in a HB one I picked up in a bunch of crap at an estate cleanout decades ago. Just found it again a few weeks ago.

The part number could be useful. There are operating potential differences among the series and many different CRTs.

Hohos?

It cracks me up Fred that there are so many of them floating around out there for less than 50 bucks or even for free. I've seen several different original manufacturer list prices for the 485 but +$7000 seems to show up frequently. Maybe someone here knows what they actually sold for when new. It makes me think that with values like that we live in the best of times, eh?

HO-10, HO-13, SB-610, SB-620 I guess, but you can probably add others to the list.

sounds like a 913. National CRM scope used one.

I picked up a dual trace 40 Mhz Leader either on eBay or at a hamfest... not sure I actually got a few from both... it was under 40 bucks.  I use a BNC female to BNC female that attaches from my A trace to the back of the Johnson Matchbox with the RF probe.  Works great for envelop monitoring.  I can see when I turn up the audio gain that it will start flat lining with overmodulation so I cut it back until I have about  95% negative and 100% positive from the Johnson Viking II.   Today I asked Pete WA2CWA about my signal since he was working me on 15 meter AM with his Flex 5000.  He said it looked great with no artifacts or splatter, nothing seen outside of the normal bandwidth.  

I have never setup a trapezoid and I wonder if it would be as easy as pulling my audio out somehow to monitor it on the B trace?

I have never done this myself (caveat) but from what I have read here, the only way to get an accurate trapezoid with a plate mod. rig like the V2 is to get the audio off the modulator secondary using a voltage divider network (resistor string) and feed it directly to one pair of CRT plates on the scope.  how much voltage needed I don't know.

That is false. The concept of running anything directly to the CRT plates is unsound and unnecessary if you have a good scope. It dates to the days when scope hams had access to had very limited bandwidth or were POS like the HOhos and other "monitor" scopes.

So we agree to disagree.

Diode demodulated samples will never make an accurate display in my opinion.

73DG

I was talking about scopes not diodes.

I was talking about the source of what the scope looks at.

Reconstituted audio from RF (from a diode or some other detector) is never as linear for display against the RF input for a accurate trapezoid measurement.

It manifests as 'bent sides', making one misinterpret the problem is a ratio error in the modulator/RF within the transmitter.

Like using a out-of-calibration VOM to build with.....

On most ham operations, it would be plenty OK, but to set up a big BC transmitter it just doesn't proof out.

Many here want to dot the I's, eTc, hence my references.

73DG

I think I'll stick to just monitoring the envelop for now.

I understand and I completely agree. Any measurement is only as good as the sample/source. I still don't see how any of that relates to how the scope is used. Maybe I'm missing something (yea, yea, I know, a lot)?

My comment isn't about the scope at all.  It is about how one hooks it up (or buys a 'one box' unit) to monitor modulation.

To wit, if you're running plate modulated tube rig, checking modulation via a trapezoidal pattern will not be accurate without a tap directly on the modulation transformer secondary.

I interpreted your earlier comment to assert contrary.

73DG

If you are using a good quality lab grade scope, running the rf and af signals through the horizontal and vertical amplifiers should be OK. But why take up the desk space and tie up a useful test instrument as a permanent modulation monitor, when about any old el-cheapo HO-10 or other Hammy Hambone monitor scope will do the job? Bypassing the built-in amplifiers and feeding the plates directly guarantees linearity, especially if both deflection plates in each axis are excited in balanced fashion.  No noise/hum or spurious artefacts introduced, what you see is what your signal really looks like. Sure, it takes a larger signal sample for direct CRT deflection, but that means a better s/n ratio and less likelihood of extraneous pick-up and still should amount to no more than a fraction of a watt siphoned off from the transmitter output.

I can't think of anything that would be fundamentally "unsound" about feeding the plates directly.

My first monitor scope was homebrew.  I fed the vertical plates directly with the rf sample, and used 60~ a.c. for the horizontal sweep.  It kinda sucked, because I got two images superimposed on top of one another, moving across the screen in opposite directions, but I could at least tell my percentage of modulation, and with a little practice, it was possible to figure out what the envelope waveform looked like.  Then I came upon a  circuit, in a West Coast Radio Handbook IIRC, which involved adding fewer than a half dozen components (resistors and capacitors) that formed a 90° phase shift network, and feeding that shifted a.c. to the control grid of the CRT, so that it blanked out the trace over a half-cycle, virtually eliminating the undesirable re-trace.  Not perfect, because the display was expanded in the middle and compressed at the edges (since it was still half a sine wave and not a saw-tooth), and the sweep rate was fixed at 60~, but it still gave a pretty good indication of what the modulation waveform looked like.

I later replaced that scope with a hamfest find, some kind of speciality test instrument that had direct access to the plates and variable linear sweep, until the irreplaceable CRT crapped out, and by then I had acquired the HO-10, another hamfest bargain. I modified it to feed the vertical plates directly with rf and to feed the horizontal plates directly for trapezoid mode, disconnected the two-tone slopbucket garbage, and corrected Heathkit's shitty design that caused hum modulation on the display, and have been using it for years, with three other HO-10 carcasses in my junk pile for what should be a lifetime supply of spare parts.

One thing to beware with ANY CRT scope is that if you monitor in trapezoid mode all the time, it will eventually burn a vertical line in the middle of the screen, since whenever there is absence of modulation as between words or during speech pauses, the display is reduced to a bright vertical line. I use trapezoid mode only for occasional checks for modulation linearity and a more precise indication of modulation percentage, and otherwise monitor the envelope waveform.

The envelope display will burn a horizontal line across the screen, and the trapezoid will burn a spot in the middle of the screen, unless some method is used to disable the display during stand-by periods.  I use a simple and dirty method that nevertheless works.  My T/R relay system operates with 28v DC, so I simply couple T/R control voltage to one of the horizontal plates, which shoves the baseline trace off-screen to one side, and during transmit, a set of relay contacts breaks the DC line and allows the baseline to shift back to its position on-screen.

It is especially important to use some method to blank the screen during receive/standby to avoid ruining a good test scope, if it doesn't already have an automatic trigger function to blank the screen in the absence of a signal.

To monitor one's CW waveform, it is best to simply turn down the brightness and leave the display triggered, since it would be difficult to interpret the display if it blanked out between dits and dahs.

I suppose there is nothing fundamentally unsound in bypassing the fuel pump in your car and pumping it by hand. But given the fuel pump works just fine, it would be rather silly to bypass it.

Good scopes for on-air monitoring can be bought at any hamfest for less than $100, often less than $50. Why mess with a POS like a HOho? You have to make kludges like connecting directly to the CRT plates, adding a triggering circuit, building a real power supply....  and you are still left with a very small screen. It's a waste of time and a far less effective way to make a measurement or monitor the signal. It's a hammy hambone way of doing things. I would never recommend to anyone to waste their time or money on a toy like a HO-10.

To each his own but the effort in getting a POS like a HOho to work correctly is better spent in other parts of the station.

Pulling the beam off screen is one thing, but running the beam current for minimum intensity during zero RF and audio and then causing it to increase to a normal level during modulation is more elegant and might have advantages depending what you want.

A scheme that will work for both the trapezoid and the amplitude monitor hookups is to rectify samples of both the audio and the RF and use them together to intensify the beam current. When no RF or audio is present, the beam is left dim (as set by the intensity control).

1.) Upon the first cycle of audio, a rectifier charges a capacitor and that voltage feeds to the control grid of the CRT through a resistor. The capacitor time constant is set for longer than the lowest modulation frequency so that upon modulation a DC steady voltage is produced.

2.) The same for RF, so that a DC voltage is produced according to the peak RF voltage.

3.) A special CRT trick is to add another RF detector and the time constant of the RF detector can be set to follow the audio waveform rather than filter it, just like an AM detector. A small part of this signal can be applied so that the effect is minimal at 100% negative modulation and maximized at 100% positive modulation. It has the effect of making the entire image of a much more uniform intensity, as opposed to leaving it to where the -100% part of the pattern has the same beam current as the +100% part of the pattern. It does not work 100% perfectly but it is a noticeable improvement avoiding bright spots/lines and large dim areas in the waveform or pattern.

Only a few volts or tens of volts is necessary to intensify the trace depending on the CRT. Each of 1, 2, and 3 can have its own screwdriver adjust pot to set the magnitude. The entire pot serves as the R of the RC time constant.

The wipers of the pots can each feed through a high value resistor to the control grid. The 'cold' ends of the pots should be connected to the CRT cathode. The value of these resistors depend on the values of the resistances in the CRT circuit and should be large compared to the resistance between the cathode and grid, about 10x, so that adjustments will not affect the brightness control much. The values of the adjustment pots should be about 1/10 the value of the series resistors so that the adjustments will have little interaction.

This assumes the CRT cathode is the connection for the decoupled negative HV CRT supply and the (more negative) grid bias comes from the brightness control wiper. If the CRT circuit is such that the decoupled negative HV CRT supply is connected to the grid and the cathode is therefore connected to the brightness control wiper, then the polarity of the voltages generated should be reversed (negative going) and the pot wiper series resistors should go to the cathode and the pots' common to the grid. The case could be either depending on the scope or the circuit chosen. Just throwing ideas on the table. A very lazy way of doing something similar could be to take the +HV for the CRT from the transmitter - when the HV is keyed on, the CRT accelerator is also keyed on. Depends on the CRT as most will be very dim with no 3rd anode voltage.

Well, this thread seems to have devolved into a semi interesting airing of everyone's opinions about monitor scopes.  Mine is that any monitor scope is better than no monitor scope. ???

At the risk of getting back to the original subject.... I live in Tyler, TX about half way between WW9W and the rest of the 3890 crew in north Dallas.   I normally listen to AM on a 75A4 but split the RX path and feed the other half back to my Elecraft K3.  The K3 supports a "LP-PAN" panadapter that runs full screen on a 22 inch monitor.  If it's out there, I can see it.

I usually monitor the 75M AM window till around 10AM when I move to 7160.   You do see the occasional over-driven audio type signal and most of the heavy iron rigs appear a bit wider than  the typical ham TX.   What I don't see is the 10's of KCs wide signals reported by the lid with the cheezy ricebox pan-adapter.

When I first started using the LP-PAN  setup my impression was that most of the SSB TX's in the world had poor unwanted SB suppression, because I could see the "other" SB on the pan-adapter.  A little further down the learning curve I figured out that a normal SSB signal that is 40 db above the noise is going to show the other SB at around 10 db.  30 db being fairly typical SB suppression.

Some of the really strong AM stations, like say Robert's, hit me 60 db above the noise floor and I can see artifacts outside the "normal" passband but they are 50 db or so down from the CXR and do not constitute a problem, just the normal reception of an extremely strong signal. 

When I TX, the panadapter goes into gross overload and shows my CXR appearing again about every 10kcs over the entire 190kc's it monitors.  Near as I can tell there is only one actual signal there. 

I think this is whats happening to the lid that did the u-tube postings, the difference being that he is too uneducated and/or un-intelligent to understand that what he is seeing is created by his overloaded POS ricebox.

73 Jack KZ5A

QOD - Does "the minimum power necessary for reliable communication" cover running enough power to keep the SSB operators at bay? ;D ;D ;D

30 dB is piss poor opposite sideband suppression for a modern rig. Even my CE 100V beats that and it's 55 years old.   But that's an SSB topic for another time and place.

Many seem to be confused how to hook up a modern broadband SS scope to an AM rig as the ARRL lost interest long before anything like that arrived.

Perhaps a tech article in the proper forum section is due. Or even in ER or horrors....QST!

Carl

This may well be the case,Tom. But it may also be showing the point at which the receiver can no longer handle strong signals and whatever stage is crashing starts to generate massive IMD.

The only way to straighten that out is to have the receive op crank in enough attenuation to be definitive.

If we're gonna start throwing eggs at each other we better be abasolutely sure of our fact. These videos are in no way conclusive.

Yep, it could be the receiver being heavily overloaded. That's why I mentioned it in my comments above.

I certainly have no axe to grind. Never met or heard him on. Just going by a video that may be accurate or invalid.   Maybe he does have a problem with the rig or maybe not.  It's better to have some proper tests run than for us to speculate and sweep it away. I've had problems pointed out with my rigs and was always grateful - and jumped on it right away.  Some were real and some were not.  It's hurts all AMers if there are real problems with our rig and nothing is done to correct it.   Has anyone contacted him and offered to help? How far is Lorraine, Ohio from him, Bud?  ;D

T

Did anyone notice that those videos are dated July 2010?

But the very wide splatter I mentioned from Maine in an earlier post in this thread was in the past month or so. (But I haven't heard it since.)

Its the Icom that cant deal with the big AM signal.  Its full scale to that front end. 

As the crow flies I'm 981 miles from Robert. I have heard and qsoed with him many times and didn't notice what is shown in the video. I've been in qsos 5kHz from him and not had a problem. FWIW!

old stuff that has been fixed long ago. but still some good reading in the thread for sure.  i'd like to find out who is making all these lighting crash sounds in my rx in the middle of january? haha

"Did anyone notice that those videos are dated July 2010? "

"old stuff that has been fixed long ago."



Cheezz... That's over 18 months ago.  Another 10 minutes of my life wasted...  ::)   ;)


T

I saw that right when Don posted the links at the start of the thread. You guys aren't very observant.

There was LIGHTNING just south of me this morning when I got up and looked on the Vaisala thing.   ??? 

It's frigging JANUARY and I guess I can't even relax and leave everything hooked up in the dead of winter anymore.

Yes, I was aware of the date on the videos.  But if the problem was "fixed long ago", why haven't the videos been taken down?

Besides, some here don't seem to agree that the issue has been resolved.  Re-read replies #2 and #3. OTOH, the thread on QRZ.com (http://forums.qrz.com/showthread.php?326248-AM-Bandwidth&highlight=AM+bandwidth) just appeared less than a month ago.

The issue is not how long ago something was posted, but the fact that complaints about "bandwidth" and "splatter" aren't just limited to slopbucketeers griping about AM; AMers are complaining about other AMers on non-AM forums, drawing previously disinterested members of the amateur community at large into the fray.

If this isn't going out of one's way to instigate more "bandwidth" controversy (and possible petitions), I don't know what is.

Most importantly, it behoves all of us running AM to take measures to assure that our signals really are clean, and that the inevitable complaints we do get are without merit.

It's My Wirl..................It's My Whirl...............
From the Prudential commercial......I wish I could find the clip and send it to JJ....I cannot figure out if Tom wants to AXE us something or he is grinding a new AXE.
geday

A good example of a splattermaster, the SW broadcast station on 21.630 MHz is severely overmodulated and is splattering all over the 15M band.  Discovered it today while listening to some 15M AM ham stations.   I sent an email to the stations website.

They just switched transmitters or dropped power and it went away 14:30 EST.

It's still there. I can hear it right now. Incredible splatter!

The SW broadcaster is not really the topic here but well could be..that's downright nasty!..this station a religious oriented station on 21.630 has been "splattering" for over 3 months..at times reaching as far as 600khz left and right of the main signal..I left word with W0TDH to contact Chuck Skolaut to look into this..this is the 2nd time I do this..for awile they seemed to heed the concern as they were very "clean" signal wise..methinks it's time for a new engineering crew there or if no crew then hire one..I guess the lesson is if ya want to really experience splatter..head to 21.630 and tune up or down..FWIW there's my rant on this subject although it is off topic a bit....by the way Steve I hoid ya today on 15mtrs just b/4 I yakked it up with Bill..nice signal!  73 de DAVE

Call the station again and tell them you are going to complain. They might not even know it if it does not always happen. Maybe some poor engineer can make a buck if the station fears the FCC. It could be an arcing issue or something, they think its fixed but the root cause was not found?  I can't pick up the station.

That station is putting some of the CBers to shame with the wide signal. It almost sounds like FM!

Steve, are you talking about the SW Holyroller broadcaster or the Ham station originally talked about?

The shortwave station I heard yesterday.