The AM Forum

A neighbor down the road mentioned he had some "old" electronic equipment and I should come down and get it.

The photo is what I picked up, it has stenciled on the top "USN" and from the dates inside (I had the case off right away) the chassis says wired in 1977.

It looks to be a line level amplifier with equalizer and 130 watt output into 4 ohms.

I am trying to think how I might incorporate this into the ham shack.  Or, is it just going to be a dust collector with limited ham potential?

73, Tom

I have worked on these before.  the output transisters are common power supply parts.  easy to come by.  spray out the pots with de oxit and use it to power some speakers in the shack. 

It could also be used to drive a couple fat old triodes in a class B circuit. Some people don't like this method but with a solid amp hooked up to a reversed audio transformer going to the grids, it works just fine That is what I do on my BC-610. Lots of head room doesn't hurt!

Sorry to have to say that's (older) Peavey junk.
Not good or useful for much other than making icky PA sound.

Can get a schematic if you need one.

Sell on Craigslist and get something useful. Imho.

                   _-_-

that is cool^2. You should use it. Peavy stuff has a good frequency response and if you run some ohmic protection between it and the speaker all will be well on both ends.

cool ^2

1. an old Peavy amp, easy to service. rock n roll.

2. owned and used by the military, and obviously the sailors to whom that equipment was entrusted made sure every cent of taxpayer value was extracted from it before turning it in*




* When I got my first M35A2 6x6 truck, it was a former Marines vehicle that had an electrical panel inside its bed-mounted S-280 shelter, with two 3-phase variacs, one 60 and the other 400Hz. They both had a terrible dead/wore out/burnt out spot. Totally used up.

I was in the Texas State Guard at the time, and one was welcome to use one's own vehicles and gear, except for weapons and other specific items which were either 'specified for the soldier to buy' or 'issued from the armory or shop and returned'. The State Guard is a mix of civilian personnel including police, firefighters, EMS, businessmen, and of former military personnel of all and similar qualifications in addition to whatever warfighting skills they brought in.

So I had already removed the variacs and wired the connection straight through, which also converted the 400Hz side to 60Hz. The vehicle now could be plugged into six 120V 30A sources, or two 208-3 phase, or whatever. But this is getting off track.

I frequently drove the M35 to drill and training. Just because. One day at drill I had already pulled out the variacs to show to another communications NCO. Another buddy of mine, who is a former marine E7, happened to be standing in the hatch of the shelter. He liked the shelter because it was ex Marines equipment and also our communications central and jump TOC.

He was so large a man that he filled the hatch in just ACUs, said hatch which is large enough for a soldier to run in or out of carrying full battle gear. And he was not a fat man, but just one of those very big fellows whom one could imagine in hand to hand combat as ripping one enemy's arm out and beating another to death with it.

I said to him, "Look at these variacs, the Marines have completely burnt them out and totally f'd them!  He looked at the burnt spots, then to me, and said, "what do you mean, PJ?" (PJ was my nick). I could tell his tone was not so amused  and I did not want to make an insult.  I said, "It's obvious the conscientious Marines to whom this equipment was entrusted made sure every cent of taxpayer value was extracted from it before turning them in". He started laughing.

Well, some good thoughts and some not so good.

For me it has the disadvantage of being huge... heavy.... and a bit ugly.

But, the idea of repurpose for a modulator does intrigue me.

I am afraid it will settle on the back shelf while I finish all the projects that need to get done.

Started three chassis work today for a 5 watt AM transmitter that got my attention before the Peavey.

73, Tom

If you have multiple radios, build an audio select panel and use the amp for the station speaker driver.

(http://i670.photobucket.com/albums/vv62/mikeinkcmo/Radios/Station%20KE0ZU/AudStationCntPnls_zps95ndtbxx.jpg)

(http://i670.photobucket.com/albums/vv62/mikeinkcmo/Radios/Station%20KE0ZU/Controller/StaConR5%203_zps2jn3nosk.jpg)
Mike

If you can find a big enough tube audio output transformer or maybe a power/filament transformer you can pair it up with a choke and cap and modulate a 100 watt TX directly. I have never tried the power transformer thing, but have heard that it works. There might be a thread here on that. I use a big old Olsen audio transformer and pa amp on my Viking 1. It works very well.
Larry

Mike the thing is three feet wide and my radio room is only eight feet....  nice panel you have built there!  Wish I hadn't let my 390a go.... it, too, was crowding the room though.

Currently my problems center on too many projects and too much stuff.

Partial list:

National NC-303 (first on last off receiver)
NC-300 (2 currently)
Hallicrafters SX-111
Hallicrafters SX-111 mark1
Drake 4a
Drake 2b
Johnson Viking II CD (plus two for spare parts)
Hallicrafters HT-37 (2 on hand)
Icom 2 meter IC-22
Icom 7600

All functional and used in some capacity.... plus all the parts and test equipment necessary to keep these critters running.

Now you know why the wife "helped" me move out to the barn!

I did that with my Apache. I used a 60 watt audio transformer and two PS chokes in series as heising reactors (20 Henry's) and a 4 uf cap at 1000 volts and could modulate the Apache at more than 125%. I received very good comments on the audio quality and in fact I think it sounded the best of all the stuff I have ever had on. My point is that you will not need a 100 watt audio transformer or higher to do the job since there is no DC is on the secondary which, in this example is reversed audio transformer configuration. Since it was just voice, perhaps a 30 watt transformer would have worked? With the advent of very high power audio amps out there nowadays, it would be a great experiment to use a plate transformer as a modulation transformer in a heising configuration. If you have a class C final running at 3000 volts on the plate and used a 6000 volts plate (mod) transformer, you could be heard World Wide!
 

 Fer yer approval

AM Amazing Transformation



klc
http://www.amwindow.org/tech/htm/tvtomod.htm