AM-141 manual or schematic? or specs for the audio driver iron?

[Opcom]

This is the 2KW amp that goes with the BC-610 I believe. I have a chance to get two replacement driver transformers.

The gentleman says they are large, I wonder how they stack to a CG-512 or PA-512 power wise.

One goes in the AM-141 and drives the modulator grids. Before I spend $ on them, I would like to find out as much as possible therefore the request for the manual! Thanks in advance!

[W7TFO]

Hi Pat,

No book, but I do have most of the power supply.  Plate trans, choke & cap.

Muy pesado!

http://amfone.net/Amforum/index.php?topic=26335.0 second picture.

73DG

[W2PFY]

The AM-141 is just a class C amplifier. It was used for RTTY and CW only. I have the manual around for it somewhere. It used the E model 610 to drive it at reduced power. There is a variac on the 141 that controls the HV transformer in the 610 to reduce power. That connects to the terminal strip on the lower right hand rear side of the 610.. It used a pair of 833A's in push pull.

It used coils on the input that were similar to the 610 but they have a fixed link. The output coils would probably handle 4 KW!

So I wonder what transformers he talking about? I would like a piece of that plate iron but it would have to be close to me

[W2PFY]

Please delete.

[W2PFY]

Please delete

[Opcom]

Interesting.. none are DG's iron, here is the list the guy sent me:

- unknown part said to be a driver - Chicago Standard 55C07 also says 138639 - I have never had Chicago catalogs with this kind of PN. This has two ceramic insulators on one side and four on the other, and it is large size. If that is a driver, I am amazed.

- UTC H-1667 varimatch trans. also says Link 57295

- Merit A-3843A 3300 CT to 500 ohms 210W

- UTC CVM-2 universal 60W audio/125W input modulator 801A 6L6 809 T-20 1608 6159

- Bendix *N217206-1 120V 145VA /6.3VCT 23A (two unuts) -finally something for the 300 pcs. 12BQ6's here?

- Chicago CTC 13373 choke / part 838004 / TF1A04VY (YY?)/ 8H 0.5A 50 Ohm reactor PWV1070

- Thordarson T-20037 10H 500mA choke unknown volts (has Navy anchor stamp)

- Thordarson T-19P67 1380VA pri 115V / sec 4900VCT 4250VCT 0.5A

So I guess they are from other things.

[W2PFY]

Well that big black one is a modulation transformer from a BC-610C. How do I know? I had one in my BC-610C and it blew out. I was happy it blew out because it had the most talk back of any mod transformer I ever worked with! Now just because mine was loud, it's not to say that one would be the same. After if blew out, I tore it apart and saved the feed through bushings. The inside was filled with pitch. I still have it and someday I'm going to heat it up and melt the pitch and try to determine what shorted. The side with two terminals would go from B+ on one side to the PA on the other. The side with 4 terminals, two would be tied together with a wire going around to the other side to B+. Two of the terminals should be marked P & P.  Is that what your seeing?

I guess you know that the 610 used two 100TH mod tubes to a 250TH final. They ran at 2000 volts. I was told that the 610C model was manufactured in 1941. I hope this is is helpful. Don't want to sound like a know it all!!

[Opcom]

That is it exactly. Thanks for identifying that transformer! I have never seen a BC-610C in person so didn't realize what it was. I now wonder of the Thordarson T-19P67 is the power unit.

[W2PFY]

I now wonder of the Thordarson T-19P67 is the power unit.

I don't know about that transformer but I think the one W7TFO has shown on another thread is the plate transformer. It ran single phase and was a single voltage primary of 110 to 117 volts as I recall.

[Opcom]

Dennis' transformer -Amertran type W 3.75KVA pri 115V sec 7500/3750V -that would be right it seems for the 141.

Not sure what the T-19P67 plate trans. in my list was from.
I found it in the 400C catalog, it is for  2000VDC/1750VDC @500mA.
Not a 610, it made 2000/2500VDC IIRC.

[KA2DZT]

Interesting.. none are DG's iron, here is the list the guy sent me:

- unknown part said to be a driver - Chicago Standard 55C07 also says 138639 - I have never had Chicago catalogs with this kind of PN. This has two ceramic insulators on one side and four on the other, and it is large size. If that is a driver, I am amazed.

- UTC H-1667 varimatch trans. also says Link 57295

- Merit A-3843A 3300 CT to 500 ohms 210W

- UTC CVM-2 universal 60W audio/125W input modulator 801A 6L6 809 T-20 1608 6159

- Bendix *N217206-1 120V 145VA /6.3VCT 23A (two unuts) -finally something for the 300 pcs. 12BQ6's here?

- Chicago CTC 13373 choke / part 838004 / TF1A04VY (YY?)/ 8H 0.5A 50 Ohm reactor PWV1070

- Thordarson T-20037 10H 500mA choke unknown volts (has Navy anchor stamp)

- Thordarson T-19P67 1380VA pri 115V / sec 4900VCT 4250VCT 0.5A

So I guess they are from other things.

The Chicago Standard xfmr with the 138639 number.  This number is a code, 138 indicates it was made by Chicago and the 639 is a date code, made in most likely 1956 in the 39th week.  These number codes were used in the 40s 50s and maybe the 60s.  The 4th number is the year but no way to tell which decade.

Fred

[Opcom]

Thanks for the code information on that transformer Fred. If I had to guess, the cone shaped insulators tell me it's a classic but I would have never figured that out. I don't have the historical knowlkedge to date it but it is a real nice piece.

My friend came through town on his way back from a trip and dropped off all those transformers and a 13H 450mA 3500WV choke. He was about wore out because of a 6FT rack full of equipment he bought. It seems the rack was wheeled in, then years later the owner poured a concrete floor over the original deck and now the rack was 3" taller than the door and he had a heck of a time getting it out.

I gave him some of the audio iron that had not sold. I also gave him a big box of ancient WE and Altec service company repair manuals for the audio gear and projectors and Altec's price books of old. Those amp manuals are the ones from which I already scanned a bunch of audio schematics for Bunker. He likes W.E. and needs references like that, amazingly he can quote transformer part numbers and specs etc. He's one of those audio guys that builds especially clean looking equipment with the best old parts he can find and restore, and his amplifiers sound very clean. Much of it is push pull triode stuff but he also makes a very clean beam tube amp. In that way he is no different than those of us that tweek AM gear for lowest distortion (except we deal with the RF amp as well).

He gave me a fairly modern (gray panel) WWV receiver that has a 2" CRT in the front panel and receives the 2.5-25MHz signals selected by an engraved flanged knob. Also a rackmount panoramic adapter from maybe the 1970's or 80's, looks like what would go with W-J gear but it is another brand. It has one of those 3x1" rectangular CRTs. I do not know the I/F, will have to divine that but hope it is 455.

The large black transformers mentioned previously do indeed look like BC-610 modulator units as suggested. In the one picture there is a small gray UTC H-1667 varimatch trans. /Link 57295 unit. He brought 4 of those (one still sealed in the military? parts box) and we discovered I also had one on the shelf but it has no further data on it so it's still unknown. If it is a small mod unit, it may be useful for interstage or drive at low power, and if it is a plate(s) to line or intended to be a driver, that is fine too.

I also got three (potential?) transformers with 2400VAC high side with 4" insulators and 120V low side. They are 500VA. Has anyone used that kind for plate duty at higher ratings? They are larger than one might think for 500VA and seem really well insulated.

Too hot to mess with these things now, maybe tomorrow. They are interesting items and I will post images and details of what I find out about the receiver and adapter, hope it will be entertaining.

[Opcom]

Pics:
- Communication Electronics model SM8511 bandscope #147 - on 500KC

The outer limits are emphasized to compensate for the receiver's narrow tuning. This tilt function appears to be done in the adjustable many-element filter. Something is off though as on 50KC its not too noticeable but on 200KC with the gain up, the gainon the high fequency side is much more than on the low frequency side.

- Specific Products model WWVC WWV receiver
This needs some work, everything lights up but it is not receiving.

Time to go looking for the manuals.