5KC Audio

[k4kyv]

The R390’s 4kc filter was too darn narrow and the 8kc was too wide.

That's the fault I find with the R-390A.  They needed to have put a 6 kc filter between the 4 and 8.  The L-C filtering used with the R-390 seems slightly broader than the mechanical filters, so the 4 kc selectivity position isn't so bad for AM. I find the audio quality from the R-390 a lot better than that of the -A model.

[K5UJ]

Most of these receivers I have never even heard.  I have seen a few of them but that's about it.  But I am very pleased with the sound I get from my 75A3 with the mechanical filter out and just the IFs and a RC filter that's about 15 KHz wide and the tap on the AF pot wiper out to a p.p. 6BQ5 amp.  The A3 doesn't have the flywheel spin but I like the PTO.  As you all know, the gain with tube stages is really something!  OTOH the stock A3 with the 3 KHz mech. filter, stock audio and envelope detector would not be good in terms of audio quality.  Here's an interesting bit about Collins price back in 1954:  The 75A3 listed for $530 from most dealers.  That was around $40 to $50 more than a new SX-88.  What is wrong with that picture.

[k4kyv]

I believe if you can find the spinner knob and gear reduction mechanism, that the spinner knob can be used with the A3 and A2 as with the A4. Also with the 51J/R388 series.

The spinner knob/vernier mechanism on one of my A4s was trashed by a previous owner.  I found a replacement kit from Collins in the old Ham Trader Yellow Sheets, virgin new in the original unopened box, for $35, back in the 1980s.  I installed it in the receiver and of course it worked excellently.  To-day, that mechanism would probably fetch more $$$ than a whole 75A-4, and the owner would not dare break the seal on the original factory box lest it lose over half its value as a "collectors item".

[w3jn]

Many professional receivers have a 16 KC bandwidth position - R390 series, any number of Racals, the RF-590, WJ 8716, etc.

[k4kyv]

It's two-way emission A3E regardless which applies to commercial, amateur, CB, etc.

If some want to interpret it as not including amateur radio that is fine. I'm one of the people who considers it being part of the same. Lets not beat a dead horse any longer.

The bottom line is  that we are governed by Part 97 of the rules and the Communications Act of 1934 as amended.  Where in Part 97 does it say that we are subject to limitations laid out in Part 47?  If that were the case, those same Part 47 provisions would be repeated verbatim in Part 97 or else there would be a cross-reference to it.

Another point the FCC mentioned in one of their rulemaking proceedings some years ago: "The amateur service is not a personal communications service.  It it a highly technical radio service" which  implies that, unlike CB and commercial land mobile, the standards applied to the two-way voice communications services do not apply to amateur radio voice communications.

[K5UJ]

I believe if you can find the spinner knob and gear reduction mechanism, that the spinner knob can be used with the A3 and A2 as with the A4. Also with the 51J/R388 series.

The spinner knob/vernier mechanism on one of my A4s was trashed by a previous owner.  I found a replacement kit from Collins in the old Ham Trader Yellow Sheets, virgin new in the original unopened box, for $35, back in the 1980s.  I installed it in the receiver and of course it worked excellently.  To-day, that mechanism would probably fetch more $$$ than a whole 75A-4, and the owner would not dare break the seal on the original factory box lest it lose over half its value as a "collectors item".

Someone (I think it might be the guy who makes those brown plastic snap-on spreaders for OWL) sells a weighted spinner knob for the A1-A4.  I looked at it out of curiosity but it was way way too rich for my budget.  I think it was around $200.  This is nowhere near a big enough problem to warrant a $200 solution and anyway I like the stock look of the A3.  I'd rather spend $200 on parts, variacs, stuff like that.  Oh yeah, there is the thing I found:

http://www.73cnc.com/73cnc/collinsaline.html

I imagine the production cost (having the mold made and getting some injection mold business to make the parts) was pretty high so I'm not quibbling over the price; rather I have higher priorities for my cash.

[WD8BIL]

I never implied that AM amateur receivers ......,

Just ask yourself this guys, why is the typical AM receiver bandwidth 6kc?

Ok, I must read it wrong.
And ur right. You didn't say 5KC. You said 6KC. My bad.
But the typical AM receiver ain't 6, either!

[WBear2GCR]

My browser must be defective??

I don't see the opening post by someone named "Brian" anywhere... what am I missing here??
The first post I see is a follow up by WB8BIL...

                _-_-bear

[Steve - WB3HUZ]

Narrow bandwidth equals narrow mindwidth.

[k4kyv]

Rob, I have seen those weighted knobs at hamfests.  They have a good feel, but I am a  little leery.  The extra weight exerts a lot of lateral force on the shaft of the vernier mechanism, which it was not designed to handle.  Of course, if you don't already have the 4:1 gear reduction, the weighted spinner knob is useless, and I suspect finding one to-day would be about as likely finding a bag filled with $100 bills abandoned on the side of the road, and that's about what it would take to pay for one if you did find it. I was extremely lucky to find mine when I did.

Bud, as for "typical" AM  receiver selectivity, if it is of the vintage variety I would say it is about the same as "vintage" broadcast radios: about 4 kc at the -3 dB point, and more like 20 kc at the -30 dB point. I know that's about what my pre-WW2 HRO has; maybe a little tighter than a typical BC set because it has two i.f. stages at 455 kc.  The phasing type crystal filter is of limited usefulness because it has close to optimum CW selectivity, but also has broad sloping skirts.  They can be useful for "exalted" carrier AM reception, using them as sort of a synchronous detector by letting the carrier fall right on the peak, which makes the amplified carrier do a better job at demodulating the sidebands.  But you have to be careful of phase shifts to make that work.

Collins started a revolution of sorts in early 50s with the mechanical filter that offers a nearly flat passband with extremely sharp skirts. Contemporary rigs often use ceramic or crystal lattice filters to achieve the same result.  IMO, about the best i.f. selectivity around is that of the R-390 (non-A) or the R-392, which achieve selectivity approaching that of the mechanical filters, using tuned circuits with carefully controlled coupling and resistive loading. The phase shift distortion with tuned circuits is not as objectionable as that of the mechanical filters, and that's the reason the R-390A doesn't sound as good on AM as the plain 390. It's a pity they did not include a nominal 6 kc selectivity position between the 4 and 8 in both versions of the receiver.

Interestingly, the military did not go from the tuned circuit i.f. stages to mechanical filters to improve selectivity.  It was part of a cost-cutting measure.  The original R-390 was too heavy and too expensive, so they decided to lighten things up both in terms of mass and cost.

I borrowed a Super Pro with continuously variable selectivity for a short while, but was not impressed with either its selectivity or its stability.

Steve, the way I have always put it is that the (intended) bandwidth of the signal is directly proportional to the mindwidth of the operator.  

[Steve - WB3HUZ]

Indeed. If I want to listen to 2.5 kc narrow audio, I'd switch to SSB.

Steve, the way I have always put it is that the (intended) bandwidth of the signal is directly proportional to the mindwidth of the operator.  

[K1JJ]

Part of the debate here is, "Is 5kc audio necessary?  - can it even be heard in a man's voice"?


I say, "YES it is and yes it can!"


Back a few months ago I was running my new class E rig with a sharp audio roll-off at 4kc. I thought it sounded pretty good in the monitor and was told my on-air bandwidth was a very clean ~8kc, as expected. After a week of this Chris/JBL axes me for the reason I was running restricted audio. (Chris has excellent ears for critical reports) Immediately a couple others (Tron included) in the QSO chimed in the same thing. I was surprised they even knew this by listening. I opened it up to 6kc and I heard a sigh of relief on freq. All said it sounded MUCH better.  (BTW, the rig was clean and the audio chain was clean running  6kc audio.)

These guys were using receivers that could hear the high freqs.   Six kc audio requires a 12kc position on the receiver.  One has to have the ears and the receiver to hear the extreme  highs, and room ambience that it produces.  Most stock ham receivers into a speaker will not produce these results. We must come off the detector into a good amplifer and external speakers to get a big hi-fi sound, for both extreme lows and highs. The RX I.F must also be able to handle the extreme highs and some cannot without mods.  There IS energy in a man’s voice above 4kc, no doubt. S’s and CH’s, etc become cleaner, as well as other consonant sounds.


I have proven this to myself when hearing recordings sent to me from Flex owners. I've heard myself in 3.5kc, 5.5kc and 7kc and hear the difference. The 7kc is open and airy, while the 3.5kc and lower sounds just as you'd expect – like someone put a gag cloth  across my mouth...

Sure, we can use 3kc audio and get through OK, but there IS a difference in quality to a trained ear and good receiving system.

That said, I have since rolled my audio back to about 4.5 - 5kc and run it there most of the time to be a good neighbor on the bands. To me, 2.5-3kc audio is narrow, 5kc is normal and over 7kc is wide, depending upon conditions.

There are many Amers who find 3kc audio satisfactory. The mil nets, stock rig guys abound. That’s FB.  But to a trained ear using a good RX system, the differences in 5kc+ audio can be heard in a man’s speaking voice - and it is significant to some hi-fi AM enthusiasts.

T

[KF1Z]

My browser must be defective??

I don't see the opening post by someone named "Brian" anywhere... what am I missing here??
The first post I see is a follow up by WB8BIL...

                _-_-bear

It was from a different thread that got locked out and many posts on the subject deleted...

[ka3zlr]

My browser must be defective??

I don't see the opening post by someone named "Brian" anywhere... what am I missing here??
The first post I see is a follow up by WB8BIL...

                _-_-bear

Hi Big Guy,

 There was a Probable Personal Bias lingering about and a Hidden intervention came upon
the Forum yesterday an excersized a personal will, but the Thread continued on in Strong
an in AM Fashion. 

Well done I'm glad the discussion continued.

73

Jack.

[ka3zlr]

Yes Sir Peanut gallery Member #8 Present an accounted for..LOL

Oh an as far as any issues tossed around sometimes making good
friends takes on a sportsman like conduct little tussle here a little
tussle there a few fellas hustle an bustle that's all nothing personal
got injured on this end,  but I had fun wit the front office  

Good Afternoon Everyone

73

[ke7trp]

I think the FCC will step in and start to control this. The single reason is the Flex radio.  Hams are now running 8 to 10 KC wide SSB with these things as there are no limits on the bandwidth. Its really upsetting SSB operators. I hear the Flex guys on AM. "I have it at 50KC now, How do I sound?" ect.. 

I am glad I have the filter in line. I have learned so much in the last few weeks. Its just idiotic to run the way I did for a year. At 25KC wide, Nobody was even listening to me past 6 to 8KC.  I ran a poll on the air and very few people ever use the 16KC of the recievers they own.  Once in a while when its full scale conditions its fun to open it up. I run 8 to 4KC on the reciever most of the time to kill the noise off.

I am at 10KC now.  Its a sharp, sharp cutoff.  I used an RDL labs Stick on NRSC filter. If you can find one, They are cheap on the ebay.  You can add this into your audio rack in minutes.

You can buy the new "Kit" but its $450. It includes the filter, and the DE and PRE emphisis modules.   Look for them used.  THey even have an AGC unit really pumps up the audio.  At $50 used on ebay.

Anyone know of any other cheap options for a filter?  I think if there where simple and cheap options, Hams might try it.  But there is so much of this the MORE then better mentality out there on the bands, Its probably a worthless thread.

[ka3zlr]

Hi Clark,

Ya know for a time they were a Marvel, I thought Wow look at this Bandwidth Magic at your fingertips in DSP no less. Dig this man
Then reality sunk in like it always does and before I got this Small Cell Cancer I was Studying these things on the air monitoring their signals
in phone CW Digital meaning PSK31 the ones I could catch collecting making comparisons building up a Data Base an those rigs have some
splatter issues you no how once in a while ya climb up a little to close on the mic or run a little to much fire in the on CW an Not paying
attention just wana get the QSO over I have seen some not so good looking sub peaks now this could very well have been someone learning
or testing an so on  but the widening you outta watch that once on an analyzer when one of is playing essb or whatever they call it The waveforms are something to see .

But they are Type accepted.

73

Jack.

[k4kyv]

I think the FCC will step in and start to control this. The single reason is the Flex radio.  Hams are now running 8 to 10 KC wide SSB with these things as there are no limits on the bandwidth. Its really upsetting SSB operators. I hear the Flex guys on AM. "I have it at 50KC now, How do I sound?" ect..  

I doubt it. The FCC is no longer interested in the burden of regulating and micro-managing ham radio the way they were back in the 50's. I think it is more accurate to say that they would rather see us just go away so they wouldn't have to bother with us at all. Why else did they stop giving amateur exams, drop callsigns by district, logging requirements, notification requirements for portable operation, the code requirement, and abandon enforcement in all but the most egregious cases of rule violations and increasingly take a one-size-fits-all approach to rulemaking?

[ke7trp]

I disagree.  Since the woman was hired the ham related letters, fines and license revocation has gone way, way up


C

[W2PFY]

I disagree.  Since the woman was hired the ham related letters, fines and license revocation has gone way, way up

Please provide link to those notices. The link I have shows no recent activity.

http://www.fcc.gov/eb/AmateurActions/Welcome.html

[Todd, KA1KAQ]

I think the bigger issue is, fewer folks on the air means less congestion = no issue. Other than the occasional horse's ass drawing attention to themselves and the few who will always press for it based on their principals, I really don't see it being an issue for us.

I think it is more accurate to say that they would rather see us just go away so they wouldn't have to bother with us at all.

Which will eventually happen, through attrition. I wonder if they have some threshold for activity before they consider the service no longer viable?

[W1AEX]

I think the bigger issue is, fewer folks on the air means less congestion = no issue. Other than the occasional horse's ass drawing attention to themselves and the few who will always press for it based on their principals, I really don't see it being an issue for us.

Very valid point Todd. On 80/75 meters, following expansion of the U.S. phone allocation, the area between 3.6 MHz and 3.7 MHz remains a vast sea of open space. People call CQ and have nice one-on-one conversations without a single interruption or collision between phone modes. The area from 3.7 - 3.8 is somewhat more populated, but quite friendly as well. Your other thought regarding a threshold of activity is also valid as well. It seems, however, that the pressure for HF frequencies is slacking off as more services go up and beyond UHF. The very characteristics of propagation that make HF interesting to us, make it too unreliable for other services.

I have to agree with Don too. The FCC has clearly backed away from the table and is in the other room washing their hands. They're busy leasing frequencies in the GHz bands to raise revenue...

[k4kyv]

Very valid point Todd. On 80/75 meters, following expansion of the U.S. phone allocation, the area between 3.6 MHz and 3.7 MHz remains a vast sea of open space. People call CQ and have nice one-on-one conversations without a single interruption or collision between phone modes. The area from 3.7 - 3.8 is somewhat more populated, but quite friendly as well. Your other thought regarding a threshold of activity is also valid as well. It seems, however, that the pressure for HF frequencies is slacking off as more services go up and beyond UHF. The very characteristics of propagation that make HF interesting to us, make it too unreliable for other services.

I have to agree with Don too. The FCC has clearly backed away from the table and is in the other room washing their hands. They're busy leasing frequencies in the GHz bands to raise revenue...

This could be a good thing because commercial interests won't be knocking themselves out to grab our HF allocations. The down side is that the FCC and national agencies in other countries may consider HF too unreliable to be worth protecting from electromagnetic pollution generated by "incidental radiators" like switching power supplies in consumer junk, digital devices, BPL, power  line interference, CFLs, touch lamps, ad nauseum.

HF's one redeeming attribute is its value as a back-up means of  long distance communication in case satellites and undersea cables are disabled either due to natural events (an unusually intense solar flare, earthquake or undersea volcanic eruption) or deliberate sabotage (EMP detonations, earth-bound jamming of the up-links, or deliberate destruction of the cables).  Unfortunately, that value will probably be ignored by the bean-counters because of the unlikelihood that the inevitable catastrophe will happen within the next month or the next six months.

[W2PFY]

There are a number of ship to shore operations still in operation around 4-18 MHz doing emails. They say they are more reliable than satellite and less expensive.

http://globewireless.com/network.php?page=hf

[K5UJ]

<<<The down side is that the FCC and national agencies in other countries may consider HF too unreliable to be worth protecting from electromagnetic pollution generated by "incidental radiators" like switching power supplies in consumer junk, digital devices, BPL, power  line interference, CFLs, touch lamps, ad nauseum.>>>


I think it has become obvious that the decision has been made.  They have in fact deemed HF to be not worth protecting.

This is, in my opinion, part of the fruits of the "war on government" especially government regulatory agencies which was begun in 1980 by the Reagan Administration, and more or less continued right up through the Bush and Cheney years.  Gov't agencies such as the EPA, FCC, (and now we can add the Minerals Management Service to the list) and others were routinely regarded as a waste of money, unneeded, unnecessary, and a damper on private industry and the free market.  So, they were underfunded. 

The best government money can buy was purchased by industry lobbyists who influenced or tried to influence such agencies as the FCC and the MMS.  All you have to do is look back to the BPL deployment for an example of how the FCC kept their hands off the electric power industry, ignored competent engineering advice, and looked the other way at every turn in this sad saga of an agency perverted into ignoring its charter and becoming a BPL public relations firm instead.   If it had not been for the ARRL relentlessly calling the FCC out on its shirking of its responsibility to regulate unintentional emitters, ultimately taking them to court, we'd probably have a much more severe BPL problem.

It shouldn't have to be that way, but the results of roughly 30 years of war on the federal government's regulatory functions can't be reversed overnight.   The sad thing is a lot of hams backed these administrations.  Well.  As my former boss down in Alabama would say, "Now y'all are just going to have to sleep in the bed you made for yourselves."