AM Heresy!

[VE3GZB]

Sometimes it comes to a point where I'm itching to get on the air and after so many delays and frustrations, I just want to make some contacts. I feel like I'm a ham in license only, never making any independent contacts on my own.

So yea today I did the unforgivable - I picked up an SSB rig today, very cheap, along with a KW-E-Zee tuner. It's a KW2000B and it seems in very good condition. Previously it was owned by the Air cadets. Then given to a ham who lives about 2 hours north of me.

He had found and replaced bum tubes but he couldn't figure out how to run it. It has the manuals included but operation and troubleshooting information isn't quite as thorough as I'd hoped.

Alas, I'm doomed to be delayed even more. I don't have the original mic and even following the instructions, I'm unable to get the receiver or the transmitter to give any indication of operation. Everything lights up. I can get built-in 1500Hz tone. Relays respond to my voice. But my SWR meter remains unexcited.

I'm suspecting mic connections at first, since I don't have an OE mic. Can anyone tell me anything about it?

If the mic connections/keying connections are as straight forward as I believe them to be, can anyone give a hint of what quick little thing may be holding it back?

All of this aside, I'm still going to work on the homebrew stuff, that will never end of course!

73s
geo

[w8khk]

I am not familiar with the rig, but the manuals and schematic are available for others to provide technical assistance here:

http://bama.edebris.com/manuals/kw/kw2000b/

If you suspect the mic may not be compatible or wired correctly, you might first try tuning it up into a dummy load on CW, this would test the RF circuits and determine whether it can produce any power.  Not sure how you are tuning it up for SSB, but if the mic is not working you will not get output in sideband operation.  Give CW a try first.  With schematic and manual, there should be plenty of additional assistance with all the folks on AMfone!

[VE3GZB]

From what I can see (my manuals I find also came with schematics), the OE mic had a "key" switch - so if that's not working/connected properly, that might be why I'm seeing no RF out.

I've pulled it from it's casing and I'm going over things to be sure there are no obvious stupid faults, then I'll Ohm out the 1/4" stereo jack to see where contacts are made within the rig. If the OE 1/4" jack is NG, I have another I can fit in.

I've had my license for over a year now and I've yet to make any contacts in spite of trying to make my own gear. I can generate the RF ok, but modulating it has been a trouble spot.

I have beautiful modulation Xformers now, and I don't plan on spending too much time on this KW2000B. I paid $40 for it, the power pack and the tuner today. If it turns out to be a bum, it'll make a good parts supply for me!

And thinking about SSB, I've been thinking about turning my AM experiments into DSB experiments. It's too much hassle to worry about filters, etc...but generating DSB with suppressed carrier doesn't seem too hard for homebrew. It might help me get some contacts finally!

73s
geo
VE3GZB

[Pete, WA2CWA]

I would suggest getting the receiver portion up and running first. A microphone is not necessary for receiver operation. Transceivers use common circuits in various parts of the receiver and transmitter. Dirty relay contacts in many of these old transceivers can be a source of problems.

[w1vtp]

George

Is this the rig?

http://www.ia.net/~wbsorsby/N5BU/KW2000/kw2000.htm

If we are to help you we need all the info we can get.  Yes, it looks like it's a 1/4" mic jack -- that's interesting.  Yeah, get the receiver up and running first then tackle the transmitter.  There are only 2 hot connections on the mic jack so you should be able to get it to go over to TX but do hook things up (ant or dummy load) and get a manual

Al

[VE3GZB]

Yes, that is the rig!

I just spent all evening looking at it. I replaced the 1/4" jack (original one had a problem indeed, it wasn't making electrical connection with regards to keying, I Ohmed it out). And believe it or not, the fuse holder for the high voltage supply was defective! Fuse was ok, just the holder wasn't making decent contact.

Caps all Ohm out good, there's no apparent fault that I can quickly identify in a few hours on the bench. Everything internally looks nearly mint, no signs of mistreatment or abuse.

Opened up the Final cage, cleaned the varicaps with this spray contact cleaner stuff, did the same for the band switch, rocked the switch to and fro to work it in. Pulled the tubes out, spray cleaned everything there too, rocked the tubes back and forth, then buttoned it all back up.

Powered it all up? Nada. Zilch. Filaments and audio run. Glow tube regulators are lit, relays click ok. And that is all that happens. But there's no apparent generation of RF (I ran a scope probe single-turn loop within the cabinet to "sniff" for any RF, I found none.). SWR meter remains at zero during tune up or if I try to feed audio. And there's no telltale "buzz" from the Xformers which I should expect if I were drawing current under modulation.

No plate current either, and oddly enough, turning the RF gain control counterclockwise causes the S meter/current meter to ascend under certain conditions!

In other words it really seems to be haywire, and what makes it worse is that everything looks mint and unmodified, so it'll really become a big ugly hairy monster to try to get running, especially if it needs new Xtals or a new filter assy.! EEK!

At this point I was really hoping that I could land some kind of bargain - I put my ad up on Ontario Swap Shop - I was hoping to get something that would at least let me talk on the air (don't care if the Rx works because I have my own Rx). I spent my last $40 out of my budget of $100 and got a bench warmer!! Makes me mad and very disappointed and very broke!

If anyone in my area (nearest centre Orangeville, Ontario) wants this rig for it's parts and/or tube value, make me an offer? it's too much to ship so it has to be in pickup distance.

Or better, make me a trade for something that is a bit older but has a better chance of working, has more hope of working and letting me make a contact or two just so I feel like I really am a Ham and not just a junk collector at this point?

I don't mind a few problems to fix, but after looking at the guts inside this thing, at how many potential problem points there could be given the symptoms, the utter lack of reception or RF generation, looking at how many switch connections, crystals, mechanical filter complexity, relay contacts, how many tubes there are to develop intermittents or opens, well I'm afraid might require much more than I'm feeling like investing, given how much I've homebrewed already.

I'm simply getting mighty tired of it, it's darned exhausting to work and build and get no contacts as a result, and I've been trying for over a year now, still nothing!

You can PM or e-mail me if you're looking for something for parts value. I'm feeling tired - and all I wanted to do was just make a few contacts and keep encouraged while I build my own system.

73s
geo
VE3GZB

[K1JJ]

Geo,

This is how you learn.  Everyone who is proficient started out as a total dumb-ass knowing nothing. We all have Johnny Novice stories of the first rigs we worked on and how they blew up or never worked again. But little by little sticking with it wins in the end.

Consider it a challenge to get that rig working. Take one section at a time and take voltage measurments until it starts to make sense.

BTW, a ssb rig is a lot of fun. I spend at least half my ham time on ssb working DX. I find it pays to switch back and forth between modes (and groups of people) to keep things exciting and fresh. That ssb rig will be a great addition to your gear - especially if you pull it back from the grave.

Start with the VFO and see if there is a signal coming out of it when you key it up. If not find out why by measuring voltages and poking around with a scope - and a VOM looking for bad connections. Bang the components around with the plastic end of a screwdriver looking for intermitents.


For the receiver, inject a sig gen RF signal into the ant jack on 80M. With the scope, find out where it starts (RF amp) and ends. One section at a time.

Post your results and problems and we will talk you thru it over time.

Good luck -

Tom, K1JJ

UPDATE:  I just took a look at the rig pic posted above. That's a nice looking radio!  Looks like a British version of a Collins KMW-2. Heck, it's tubes so you shud be able to get it going. See those 3-4 relays? They can be unplugged and pulled apart from the plastic case. Clean the contacts with alky and use a burnishing tool to clean up the contacts. That cud very well be a big part of the problem. Clean any and all relays up first, then get into it. Got a tube tester?

[VE3GZB]

On this rig, I don't think I'll touch it anymore, I'm plain exhausted from having to put so much in and get nothing out.

I work at electronics for a living, and I don't mind doing electronics for a hobby (I love it), Ham radio too.

But this rig looks like it's going to take me another 5 months to trace out. When I worked at a military/industrial repair house some years ago, we'd get jobs like this and it would take weeks of concentrated work 8-10 hours a day to get some of the military gear up and running.

I simply don't have that kind of free time or energy anymore to turn a can of worms such as this into anything usable. I used to when I was younger.

Heck I remember restoring a burned up 1948 Seeburg jukebox! It took me two years to do it! This was over 20 years ago when I could put in a 12 hour work day and still do another 6 hours of detailed work in the home lab. I figured out how to do the pain job, the colour wheel, everything on my own. Sold it some years ago too.

My offer still stands, if anyone wants to trade me for something that isn't so darned disappointing, pm me please.

73s
geo

[N2DTS]

I would also tend to want to fix that radio.

You could get on CW with what you have, cw is a lot of fun...

If you have something that generates RF, you could use the 807's to modulate it, using the VM2 mod transformer, just drive the grids of the 807's with some sort of audio amp.

I suspect part of your problem is that there is not much activity on 40 meters AM with the lack of sunspots.
I do hear ssb on 40, but not much AM.
Most of 40 meters is daytime only before the broadcast comes in.

Brett

[VE3GZB]

The 6146 rig I have breadboarded on a sheet of copper-clad PC Board oscillates, drives the 6146 well. I was going to get to hooking up a better mod Xformer when the opportunity to get this KW2000B came up suddenly just yesterday evening.

It was a 4 hour drive in total just for the privilege of paying for something that doesn't work.  

From what I've been researching, it seems that 10 watts of SSB are worth 100 watts of AM, perhaps more? Perhaps part of the problem I've been facing is that trying to work with relatively little power on AM is only something that could succeed locally like Doc Cruikshank did years ago up in Wingham with a small AM transmitter on a butter box - except here there's nobody in the village who is a ham. Trying to work anything else on relatively low power AM is proving to be just a burden, a liability, a PITA.

Maybe DSB is something I ought to look at.

I could work CW - except I don't know it. I'm going over to Orangeville tomorrow, there's a ham there, retired, who has offered to start Elmering me towards upgrading my license for Morse code. Home study just won't work for me here, there are too many distractions and interrputions from the kids and the wife once I get on the computer - so I never get it done.

Remember that old rig I put together (shown below lighting up a pair of parallel 100W lamps)? It would be awesome on CW!

[w3jn]

Jeez, Geo, you're exhausted, disgusted, and ready to quit with this radio after a couple hours on the bench?!  You obviously have *some* staying power if you restored that bad boy jukebox  

40 bux is a steal for that.  It's worth a bit of time to get it on the air.  Several have offered good suggestions with regard to cleaning relays, etc.   If not that, it sounds like a dead oscillator somewhere, or perhaps a mis-positioned switch.

You're already experienced with this so I won't go into the obvious with voltage checks, etc.  If you've done all that already get at it with a scope and make sure the various oscillators are running.  Unless it's been hammy hamboned to death it won't be hard to get it running - it's just a simple matter of zeroing in on the problem by signal tracing and normal troubleshooting techniques.

Tom's advice with regard to Johnny Novice mistakes is right on.  My first rig ever was a HW-7 - never had a contact on that.  I started out in AM with a G5RV and a Viking II, what a disaster.  If I had been easily frustrated I woulda stopped there and said the hell with it.  The biggest imcremental improvement I made to my station was a flat top dipole fed with W7FG openwire line.  Even with a hundred watts the station came alive - that gave me confidence to upgrade the xmitter, tuner, etc.  I'm not in K1JJ territory, signal-wise, but I do OK.

Anyway, look at Tom's thread on the 4X1 rig - a defeatist attitude ain't gonna generate much sympathy around here  

[KX5JT]

Geo said:
From what I've been researching, it seems that 10 watts of SSB are worth 100 watts of AM, perhaps more?

Don't believe that hype!!! Many "cliques" wont even acknowlegde your 100 watt SSB signal on 75m at night.  You have to be pegging their S-meter needle to the right for some reason to have that honor!  Maybe I'm stereotyping the good ole boys but you'll see!

But ssb can be fun when the band opens to DX, but lately I just feel so CHEAP when I work SSB.  I'm hooked on AM.  Is there an AA group? My name is John and I'm an AMaholic. 

100 Watts of AM into a full sized dipole, even if it isn't that magic 1/4 wave up in the air, WILL have you making contacts. You will have plenty of armchair copy qso's as well as plenty of not so easy to copy ones.  But there's no denying it will put you in the game.  I have been running these levels for a year now and my log is FULL of AM contacts.  In fact it's full of lengthy ragchews.  Ragchewing, technical discussions on transmitters, making friends, talking about everything from problems at the Broadcast station (plenty of BC engineers are AMers) or rounding up the cattle on the ranch or who's going to the superbowl.  These types of things are more of the norm on AM I have found.  SSB often involves exchanging a signal report (which for some reason all seem to be 59) , QTH, equipment used and MAYBE the current weather then 75% of the time comes the "thank you and 73".  Bleah.  

Sure, check out ssb if you must, it's fun working across the oceans sometimes, but don't give up on the AM Geo!!!  As an electronics experimenter, I know you'll find it to be "home".  BTW, your xtal will be in the mail Monday!  

[W3SLK]

If I can recall the KW2000 was the British answer to Collins KWM-2. I've only seen one and the person that has it, knows I like it  . But don't throw the baby out with the bath water yet. That thing uses a Japanese mechanical filter. I thought it was very well built.

[VE3GZB]

Don't believe that hype!!! Many "cliques" wont even acknowlegde your 100 watt SSB signal on 75m at night.  You have to be pegging their S-meter needle to the right for some reason to have that honor!  Maybe I'm stereotyping the good ole boys but you'll see!

When VE3AWA and I set up the antenna, he brought his Kenwood rig, 110W on SSB. Almost immediately he made contacts with it and the antenna in Indiana and in West Virginia, 20 over S9. I was extremely impressed!

I've made dilly squat contacts myself.

This rig uses tubes I can't get and don't have, uses many Xtals which are very hard to find. A failure in any one of them will spell death to this rig. Troubleshooting it will depend on assuming all of the tubes are good, something which will be a futile exercise in circular logic unless I have a verified working model for tube-by-tube comparison to weed out which components do and do not work in this rig.

So as nice as this rig appears to be, in reality it's a technical nightmare!

Relays all have good contacts, I pulled them, checked them with a power supply and a small incandescent load, I pulled the covers and applied cleaner just in case, then applied cleaner to the relay sockets, rocked them to work the cleaner in. Also I pulled all of the tubes one by one, sprayed cleaner into the sockets, rocked the tubes in and out to make sure contacts are scrubbed.

The only things which show life? The audio stage (I can hear the 1500Hz oscillator in the speaker), the relays engaging, the glow regulator tubes and the 1500Hz oscillator.
Absolutely nothing else shows any life at all.

Those sections which do run are far down on the electrical food chain in the rig, they get their juice from the +275DC bus but it's decoupled via 4.7k and 8uf. The manual has schematics. The +275 bus feeds all other circuits as well (mixers, oscillators, buffers), so because the audio and 1500Hz osc are getting their juice, the other parts of the +275 bus are electrified as well no doubt.

Wiring and general state of the rig's innards show no heat damage, no abuses, and I checked for shorted bypass/decoupling caps last night, every one I checked and every one demonstrated no shorts, no abnormal leakages.

This leaves tubes, filters, coils and Xtals, any/either one being the culprit.

Symptoms of the rig in spite of these preliminary tests haven't changed by one atom. I've learned the hard way when something is worth pursuing and when something is promising to be an endless tarball, I've been sucked into that trap before and have learned to avoid it like the plague.

If this rig is unwanted, then it's only value is for parts at this point.

73s
geo

[G3UUR]

George,
          The KW2000B is not the sort of project to start off with, so try something a bit less complicated. The KW2000 series were based on the Collins KWM-2 as someone on the thread has already mentioned, and the filter was indeed a Japanese Kokusai mechanical filter. One of the common problems with these filters is that the mechanical resonators were wrapped in foam to cushion them from mechanical vibrations, and this foam tends to degrade over the years, turning into a sticky goo which dampens the resonators so much they're ineffective and the insertion loss goes through the roof. So. you could spend ages sorting all the other problems out only to find the filter's an attenuator. Don't cannibalize the KW2000B, you might live to regret it later, just put it to one side for the day when you're ready to tackle it.

Try and get one of your AM projects finished so you can get on the air and yak with fellow AM enthusiasts. It's much better discussing fault finding over the air where you can get instant advice and ask questions more rapidly than BBs or e-mails.

On the subject of AM vs SSB, I remember back in the late 1960's or possibly early 1970's there was an article in CQ or maybe 73 on synchronous AM detection where the author claimed that some research done at Cambridge University in England showed that AM with synchronous detection was superior to SSB in the presence of noise. I haven't ever been able to trace this research, but who knows, it might be true!

Dave.
 

[VE3GZB]

On the subject of AM vs SSB, I remember back in the late 1960's or possibly early 1970's there was an article in CQ or maybe 73 on synchronous AM detection where the author claimed that some research done at Cambridge University in England showed that AM with synchronous detection was superior to SSB in the presence of noise. I haven't ever been able to trace this research, but who knows, it might be true!

Dave.
 

I know it to be good. At work (www.detectag.com) I came up with a noise reduction scheme for our new 8.2 Mhz swept board, I based it on synchronous detection but we've put a bit of a twist on it so my boss was able to patent it! It's helped a great deal on detecting a shoplifting tag through a very noisy environment!

I went back over some of my university texts and as far as transmitting goes, SSB offers a good deal more concentration of the available RF energy. Still it's a bear to work with!

You're right about the filter BTW, I've been researching this rig and it's the Achilles' heel of the unit. Not happy about that possibility.

I was working on it until about 1 am. Since the tubes were all verified and the bad ones replaced by the previous owner who I met yesterday, who also couldn't get the rig to run, and I know I'm getting the DC operating voltages into the circuit, then it leads to a worrisome conclusion that a coil or a filter has opened up. Since this rig uses the same RF heart for both Rx and Tx, this would explain what I'm seeing.

Not sure what I can do with it at this point now, I was hoping I could get on the air with it, but it's fighting me every step of the way. It's not what I wanted to see happen and it's drained me of my last $$. I think that is what burns me the most because I won't be able to afford to do anything at all until tax refund time.

In about 30 minutes I go to learn CW with another ham in my area. Then I'll try to get a nice good modulation Xformer connected to the 6146 rig and see what that does for my signal. The VFO on that rig really came out better than I expected, I'm rather pleased with it.

73s
geo

[W1RKW]

George,
About 1 year ago I was in the same situation with my 813 rig.  I was ready to take a match to it.  I had spent alot of time collecting, building, adjusting, tweaking, rebuilding, retweaking etc. etc. ( http://amfone.net/Amforum/index.php?topic=18117.0 ).  I too don't have alot of free time, was anxious to get it done so I didn't throw in the towel.  Anyone who knows me, I'm  a glutton for self made punishment.  I don't give up easily but will get frustrated and lash out.  Some times that helps and causes me to refocus and absorb the advice of others.  .

Anyway, it's got to be something that is straight forward but is not jumping out at you.  Take a break from it then start poking at it again.  You'll get it.

[VE3GZB]

Just got back from code lessons! What a refreshing thing to learn!! I learned 7 letters today, E, I, S, H, T, M, O! Next Sunday I'll get together with him (VE3CQH) and he'll tutor me on more!

He loaned me a small key and practice oscillator too! He said for now do not read any code, just memorize entirely by ear! Makes me feel very happy!

This Japanese Mechanical filter on this SSB rig.....is anyone familiar with it's technical specs (resonant freq., BW, Q, impedances)? If Digikey has some kind of filter which is similar, I can ask my boss to order one for me, then I'll try slipping it in under the chassis, not disturbing the OE filter, and see if this is the root cause.

EDIT:
The markings on this filter are:
Type MF-455-10CK
CVK2335X

From what I saw on this page the symptoms more or less match what I'm seeing:
http://www.sandrock.org.uk/radiostuff/KW/Kokusai%20Mechanical%20Filters%20in%20the%20KW2000%20Series.htm

quote: "So you think you filter is duff?

After many years of service, it is often found that the receiver goes deaf and the output on transmit drops off. There can, of course, be many reasons for this and the manual suggests various paths to follow in order to determine the cause. Valve degradation, particularly those that are hard worked, are likely targets as are cathode decoupling capacitors (notoriously although not exclusively Hunts). However, when the problems mount up on transmit as well as receive, the mechanical filter might be suspected."

Has anyone found a suitable ceramic or other replacement for this mechanical filter?

73s
geo

[Pete, WA2CWA]

A simple way to test the filter would be to first check the continuity between pins G and E and then between pins P and B. Each should be some finite low resistance. If either side is open (infinite resistance) the filter is bad. If you get continuity, then just bridge a cap., .01 mfd or something similar, between Pins G and P to see if the signal from the preceding stage gets to the next stage. This test doesn't tell you the quality of performance of the filter, but can determine if you have a problem with the filter.

[Ed-VA3ES]

You seem to give up way too easily.  I've been rebuilding a DX-100 for over 15 years!!!

Those filters  can be easily restored.  I believe there is  a website that describes this syndrome and it's cure.  In any case, the repair consists of opening the filter case, washing out the foam debris with a solvent (acetone, trichlorothane,, etc.,) adding a new piece of foam and closing up.   Here is  a  site that describes this filter repair:
http://jlkolb.cts.com/site/koku.htm

Here is  a site that describes your KW rig and some problems and solutions, including a  munged up filter.
http://tibblestone.users.btopenworld.com/kw2000.htm

Another site on the KW2000, and it's issues (including filter issues):
http://www.sandrock.org.uk/radiostuff/KW/Kokusai%20Mechanical%20Filters%20in%20the%20KW2000%20Series.htm

Good luck.

[VE3GZB]

You seem to give up way too easily.

No, I just too darned much on my plate and too little money to get things done. Plus I don't want to wait 15 years to get on the air.

[KF1Z]

.

[VE3GZB]

If I asked my boss to order this part for me:

http://parts.digikey.com/1/parts/403975-element-ceramic-filter-455khz-ltm455du.html

Would it be a suitable replacement for the mechanical filter in this rig?

73s
geo

[Pete, WA2CWA]

Do you know if the one you have is bad?? Replacing parts for no rhyme or reason really makes no sense.

[N2DTS]

What is the bandwidth?
For ssb you want it about 3Khz.

Brett