Who is using an R-392?? - Audio Output Tube Idea!

[WBear2GCR]

Wonder who is using an R-392?
Anyone out there??

I just picked one up.
I have Receiver Fever.
Seems incurable.

After browsing several hundreds of pages, including military manuals, websites and pdfs, I am completely inexpert, but dangerous.

So, I noticed that one of the points frequently made is that the audio output tube sucks power for lunch and creates a lot of heat. Collins offered (or a third party) a plug-in solid state substitute, but that was back in the prehistoric era. Not very reliable.

Seems like I read a few posts via linked stuff on google where people have used monolithic amplifier modules to make an all-in-one replacement.

I can design and build one today using a minimum of discrete components that will fit nicely as a plug-in. The idea is that despite the fact that through hole components are going the way of the dodo bird, they're still more serviceable than a monolithic package. I'd use non-critical components, so that repairs (if ever needed) down the line would be much easier.

The resulting circuit could either drive the existing xfmr (no real need for that) or a speaker load, of course it could drive a line level output as well. The max swing available is still going to be 1/2 the B+ of 28vdc or 14vdc. That limits the power available to around 12 watts, which is pretty good.

I can make one up for myself using protoboard. But I figured I'd inquire, since once ur doing it up, might as well do more than one. There's no profit to be had, but I could do a small run of PCBs, you'd need to provide the octal base (it is octal, right?) a heatsink and the parts (easy to source and cheap) and any hardware - some sort of enclosure is needed, but that might be a simple as a section of aluminum tubing or copper pipe and maybe some perf metal.

did this make sense??

Any interest??

-------------------

The other thing, somewhat concerning, is that I saw a youhootoobe video of a ruskie guy with an R-392. He checked the dials and the meter with a geiger counter (or the modern equivalent). Seems that the frequency dials and the meter are "hot". Probably radium paint!

Anyone know about this??

Also, I did not take a close look (maybe better to NOT get close??) but on the mechanical readout, are the numbers painted ON or are they FILLED IN? If the latter, one could probably remove the radium paint safely and re-do the numbers...

                      _-_-

Attachments show old-school solid state plug-in.

[WD5JKO]

Bear,

   Perhaps this Cumbria "Minifilter DSP Audio Processor" would work? I have been considering this product for my Gonset G-76 transceiver:

http://www.cumbriadesigns.co.uk/minifilter.htm

   It is a Mini 2 watt solid state audio amplifier (LM380 based), along with a DSP to include precise audio frequency high and low pass along with voice "Denoiser" and CW narrow bandpass characteristics. In my case, with my aging ears, I really need more than I get with my Autek QF-1A (analog version of above with same LM-380 audio chip) hooked to my G-76 audio output.

Jim
Wd5JKO

[W7TFO]

Never opened mine up.

Don't really care what it pulls, power is cheap here.

It runs cooler than usual ambient...

73DG

[WBear2GCR]

Jim,

That looks like an interesting board, but for me, not a candidate for internal mounting in this radio... I'd put it outboard, if I was going to use something along those lines. Also, once going in this direction, I'd want more audio power out. But that can be done even with this board as a "driver" to another amp.

I'd want more width on the filters for AM work, btw. 300-2700 is more or less SSB.
Maybe it can be adjusted? Something like 100-6000 is more like it.

Dennis,

yeah, I guess, but I'd like the output available to run a speaker...

I'm going to look around to see if I happen to have a nominal 28v regulated supply on some shelf, then fire it up.

Will be wearing my lead glass goggles...

                   _-_-bear

[N2DTS]

There used to be little kits that used a 5 lead chip in a TO220 case that ran off 12 volts and did 5 to 12 watts with about 5 total parts.
Input cap, output cap, resistor and the chip.
1 inch by 1 inch board.
I used one in my G76 instead of the crazy modulator driver/audio output design Gonset used.
Ran it off rectified filament power.
Worked great.

Do a search for audio amplifier kits. They come in .4 to whatever watts out...

 

[N2DTS]

http://www.canakit.com/audio-amplifiers

[WBear2GCR]

Sure. there are many kits/boards that use chipamps...

...as I mentioned, I'd prefer a direct plug-in that at least going to get in the same or similar form factor.

I suppose that a chip could work, but I'd be likely to want to put a spare somewhere inside the case. Chances of these things be available 20 secs into the future are low. Also to be considered, the temperature inside the case is much higher than most radios.

                   _-_-bear

[Opcom]

The meter may have radium paint on the needle and or scale. I have been told the knobs, but have never had one with hot knobs.

Its harmless if not opened and collectors usually prefer the original meter. The glass blocks nearly all.
Just don't sleep right over it every night. Daily use at 2 FT away ought be harmless, or if in doubt borrow a Geiger counter and check the level to see where the mR/Hr exposure is at the daily limit per the government. John K5PRO might even know that figure since he works with the science.

[WBear2GCR]

Ya, probably not an issue.
The Yoohootoobe vid showed radiation above ambient only when he put the measurement unit on top of the
windows (meter and freq).

Anyhow attached image is a look at the clockworks level gear train.
Wow.
The peak of 1952 technology?

I can not imagine having to design that gear train from scratch!