UTC PA-309 Transformer

[W7TFO]

Hah, time warp.  Good one.

N2DTS...One like this?

From a '47 QST ad for Walter Ashe.

Not that $40 was cheap, but it does INCLUDE delivery...

Those were the days, eh?

73DG

[KA2DZT]

I have a bc610 plate transformer on my basement floor, its been there for 20 years, in about the same spot, I use it for a step stool.
Its the early style with the 100 pound cast iron end bells, its too big and heavy to use, and its big and heavy for no reason.
Its too big to even throw out...

I had one of these BC 610 plate xfmrs.  Sat under a work bench for about 10 years.  Thought I would fire it up for testing.  It was open on half the secondary and shorted.  paid 25 for it.  About 80 Lbs of steel, 12 Lbs of copper the rest was tar and insulation.  Maybe 3/Lb for the copper 10 cents/Lb for the steel.  Made a profit.  Tough to get apart, I have a machine to unwind the core and discard the insulation.

Better check the one you have it may be bad.

Fred

[N2DTS]

I know its good, I used it in the past, but got better (lighter) iron a long time ago.
It looks something like the picture, but has the terminals on the end/sides.
I had the mod transformer at one point, little thing that was very heavy, all in the end bells I think.

I got this transformer out of the bottom of the cabinet when I was young, I could not do it now without getting a bad back most likely.

It was replaced with a Peter Dahl transformer which has no extra weight on it.
The old RCA open frame transformers are also good, light for the size.
 

[KA2DZT]

The steel end bells are heavy, of course the laminations are heavy.  The potting tar adds more dead weight.  Don't like potted xfmrs or chokes. I have a lot of them but rarely ever consider using them.

I've had more potted iron go bad than open frame iron. Some I've been able to fix.  They short from the terminals to the case, carbon paths through the tar.  You can cut the casing off with a cold chisel, remove all tar, clean it up, repair the leads, put on regular metal end bells, add some black paint and it looks like a new xfmr or choke.

[W3GMS]

I have two of those CG-309's around here.  Had to put them on furniture dollies to move them around.  I did have a 3rd one, but gave it to Tim-HLR after he had the fire so he could build another big rig.  We put the 309 in his car and had to reinforce the rusty floor boards since I would have gone right through the floor of his vehicle! 

Joe, GMS 

[Opcom]

Hah, time warp.  Good one.

N2DTS...One like this?

From a '47 QST ad for Walter Ashe.

Not that $40 was cheap, but it does INCLUDE delivery...

Those were the days, eh?

73DG

Those were the days! $40 for that 2KVA unit. $400 in today's money. The days of choke input filters too. Got to love that!

If the iron's used at slightly less current a C input can be used as well. I still have that transformer as in the ad. I did the PSUD simulations on it.

2700VDC @ 700mA, 5% ripple with LC of 10H/4uF (rect_Ipk=0.95A)
3910VDC @ 500mA, 5% ripple with C filter of 24uF (rect_Ipk=3.1A)

I'm glad you posted that ad; it made me think. The 4-1000 amp rebuild in the other project could run on 3900V @ 500mA pretty well, I think. It's a full 2KVA, much better than the typical desktop amp. PSUD seems to be reasonably good for C input on the older stuff.


About BC-610 plate iron - it's good stuff and made 1KW CCS, back in the day when that meant something.
It's the same as the Stancor P-9920:
HI tap: 2980VAC, 2500VDC @ 350mA CCS or 450mA ICAS  (3500VDC on high tap with C input)
LO tap: 2450VAC, 2000VDC @ 500mA CCS or 625 mA ICAS
(according to PSUD)

The secondary DCR of those older transformers that were not used with C input filters tends to be higher than new transformers. Of the ones I've messed with, it is not really that bad, considering. The older ones also did not skimp on the steel and don't seem to have saturated easily when used conservatively.

I don't mind the weight. I also must get a helper to move some of them, and the PA-309 is on a dolly. The point is that if these things are bolted in the bottom of a rack that is not going to be moved, who cares how heavy it is? It may also keep a tall cabinet from tipping as easily.

Would it be worthwhile to get the old iron out and run it up to a warm temp. to drive out moisture from time to time? Does not seem to be an issue in TX.
Well these are just my opinions. I guess I like the old parts as much as new.

[W7TFO]

Pat, what did you do with that god-awful heavy Amertran you got from Sam?  (I gave it to him beforehand).

Just curious, I think it outweighs a 309 easily.

I don't know why I'd refer to it as heavy, come to think of it.  There are 3-phase beasts here that top 500 pounds...and they are open-frame jobs.

73DG

[KF7WWW]

It was heavy enough... I'm just glad it wound up in the back of his van.. Who knows..  As much as is weighed.. It might still be there
I think the real surprise is that I lifted it 4 times to move it around... It's at least 150++ pounds

[Opcom]

Pat, what did you do with that god-awful heavy Amertran you got from Sam?  (I gave it to him beforehand).

Just curious, I think it outweighs a 309 easily.

I don't know why I'd refer to it as heavy, come to think of it.  There are 3-phase beasts here that top 500 pounds...and they are open-frame jobs.

73DG

The one from the military RF amplifier AM-141A & AM-141B /MRC as used with the BC-610. It's much bigger than the one in the ad.

It is not as big or heavy as the CG-309. But consider the war time CW transmitter at lowest bidder vs commercial broadcash use. I think the CG-309 core is something like 12"x10"x7".

I have not used it yet. It's 7500VCT, 3.75KVA. Monstrous and uses a 115V primary! It's good for 3300V at 1A.
So there is the issue, I do not have a high power 3KV application at this time. It would be ideal for 1 or two 3-1000's, rare tubes and expensive. Maybe a bank of 3-500Z's.
What runs great on 3KV? Ahh yes the original tubes were a pair of 833's in CW service and it was used in the AM-141 with 2KW output. No slouching but they warned not to use it for AM, maybe because the 833's would not take it for long. The rest of the amp looks like it would, and I'd bet money on a pair of 3-1000's in one for "QRO Night". Any amp that uses 3B28's for bias rectifiers is OK by me. The manual's on bunkerofdoom. Too bad almost all those amps were scrapped for parts.

I had intended to try the Amertrans 7KVCT 3.75KVA unit for the 2KVA audio amp chassis but that would mean a C input filter to get 4700V and some serious no-load regulation issue. So it is still not used yet. Looks nice on a shelf when people come by to look at the iron though.

The attachments reflect is intended use.

[Opcom]

It was heavy enough... I'm just glad it wound up in the back of his van.. Who knows..  As much as is weighed.. It might still be there
I think the real surprise is that I lifted it 4 times to move it around... It's at least 150++ pounds

It came out of the van when I got home. A 23 year old kid I know helps me move that stuff around. I hope that scope is still working well.


Rectifiers were 4B32 Xenon in the 'mobile' amplifier, due no liquids to slosh, and the wide temperature range they enjoy over Mercury. The nearest Mercury would be the 8008/872A (smaller) or 673/575A. Those are the kinds it takes with either the big Amertrans or the PA-309/CG-309. Anyway the resistance measurements will help me figure out the real output on the PA-309/CG-309.

4B32 Xenon Rectifier
Filament voltage    5V
Filament current    7A
Max PIV    10kV
Max mean anode current    1.25A
Max peak anode current    5A
Max operating frequency    150Hz
Max ambient temperature    -55 to +70C
Min cathode heating time    30 secs
Max. fault anode current   50A

8008/872A
Filament voltage    5V
Filament current    7.5A
Max PIV    10kV
Max mean anode current    1.25A
Max peak anode current    5A
Max operating frequency    150Hz
Max ambient temperature    +20 to +60C
Min cathode heating time    30 secs
Max. fault anode current   50A

673/575A Mercury Vapor Rectifier
Filament voltage    5V
Filament current    10A
Max PIV    10kV / 15KV
Max mean anode current    1.75A / 1.5A
Max peak anode current    7A / 6A
Max operating frequency    150Hz
Max ambient temperature    +20 to +60C / +20 to +50C
Min cathode heating time    30 secs
Max. fault anode current   100A

[KF7WWW]

The scope hasn't missed a lick. The Bogen is still going strong too..

[Opcom]

I'd forgotten that. MO-200! I am very glad you are enjoying it.