The AM Forum

I searched the net, Then searched through UTC catalogs.  Cant seem to find this one listed.  Its heavy. I cant lift it.  200lbs? There are six inputs on one side.  Center tap with 6 outputs on the other.  Two listed 4800-Two at 6000 and two at 7000 volts. 

Was it used in a BC rig?
What is the Current rating?

Thanks!

Clark

1 amp DC, I think. Check your catalogs for "CG-309", the later notation.

Right, it's the same as the CG-309 except a different case.

It has two primaries for 115 v which can be used in parallel or series. Each primary is tapped for 105v hence the six terminals.

I have a CG-308 which is the same except 1/2 the current (and half the weight :) )

Attached is catalog page for the PA-309.

If you build a power supply with it, be sure to put wheels on the bottom.

Only an Amp and huge.  W7TFO just stopped by the house and looked at it.  He guessed it was 1 amp. Right on the money.  I think its best to scrap it.  A modern transformer is half the size and weight and I dont actualy need this thing.

Thanks for the information!!!!

C

I think, the PA series predates the CG series,  I have info on the PA series but have to dig it up.

Later, Fred

I run CG310 rated for 3000, 3500, 4000VDC 600ma CCS
The 309 is bigger. I bet it will do 1A CCS since it is lower voltage than the CG310.
My low tap on the primary is 108V

Well, if you don't want it, I'll take it off your hands.

You never know when you might need an anchor for an oil tanker or something.

Seriously, it can probably put out 3 KVA all day and all night -- and not overheat even in Phoenix weather.

Don't scrap it.. I have one of those and it will run 1A all day long and not break a sweat. It's real quality. Some of the weight is in the end bells but still no reason to scrap it. Its potted and will last forever. It also has dual primaries. When I got mine in a trade years ago I called UTC and the engineer said it was the same part as the CG-309 except the case style was an older one. I remember the day I put it in the trunk of my Pontiac Ventura. It was heavy then and I think it is heavier now. Currently it is on a small frame with casters. If the first offer falls though, I'll come get it if only to save it from the scrap man.

As for what it was designed for - it is a standard UTC product. I don't know what commercial gear it might have been used in. Mine came from KRLD - 1080 in Dallas and was in the crate.

Turns out I'm going to be in Phoenix next week for a Bridge tournament in Scottsdale.

We own a house in Phoenix, and I grew up there and come fairly often.

The house is the house I grew up in, and if I ever want to build a really big QRO rig that would be the place to do it.

My dad was an electrical contractor and when he bought the house in 1956 he put in a small commercial air conditioner -- a water cooled unit with a water tower in the back yard.

Anyway, the AC was a 3phase unit, and that house has a 200 amp three phase electrical service to this day.

That AC unit was scrapped about three generations of air-conditioners ago.

Dave

There were a very few of those early tower type units in Dallas. A/C was very expensive in the old days.

I grew up in Yuma, AZ.  A fellow resident Ed Hansberger, held the patent on that AC system and either built or licensed hundreds of them all over the Southwest.

We couldn't afford one, but a neighbor had one and it used ammonia as the refrigerant and a slow, belt-driven compressor.  I remember playing in their back yard to the sound of a man-made waterfall in the wooden tower condenser.

Their house was always cool. 8)

73DG

An ideal place for one of those BC transmitters that run off 3-phase power. It can be difficult to impossible to have 3-phase power run to a residence.  I even recall Timtron saying that WBCQ runs its 50 kw transmitters off single-phase because they can't get 3-phase to their transmitter site. Now if your place has room for some strapping towers and antennas...

So Clark, you are going to let Dave get it, right? no scrapping?

Unfortunately it's just a normal small city lot.

But on the plus side, there are no CC&Rs and no HOA.

No one had thought of those things back in 1956 when the house was new.

The UTC PA and CG series are electrically identical, except for case style.  PA means Public Address and CG means Commercial Grade.  Their LS series (Linear Standard) underwent the same case style changes, but they didn't change the LS designation.

The cores are identical too, but they rotated the open frame types 90 degrees so that the profile is narrow and tall, instead of the original wide and low. Looking  through some of my old UTC catalogues, I see that some of the LS series transformers significantly changed specs but kept the same type number.  Some of the older and newer driver transformers  have vastly different turns ratios, and some of the power transformers originally had 2.5v filament windings that were changed to 6.3v keeping the same type number.  That must have been confusing (and possibly disastrous) when replacing crapped out transformers.

OTOH, Thordarson seems to have randomly changed their type numbers almost annually.  If you want to look up the specs on a certain transformer, you need the catalogue for the year of manufacture.  Later editions may show a transformer with identical specs, but the type number is completely different.  Must have been a marketing gimmick, but makes it hard to find the specs on a Thordarson hamfest find or the crapped out transformer in a piece of equipment.

The end bell type LS transformers also changed from low and wide to tall and narrow.

I have an LS-67 which is the old low/wide version, and the dimensions for the same unit in the 1949 catalog show it higher and narrower.

The "cube" shaped LS transformers kept the same shape.

In addition, the paint color changed when UTC went to from the PA to the CG series. From dark charcoal/black to a gray color.

I did see a catalog from one of the distributors (Allied? Radio Shack?) from about 1948 where both the PA and CG versions were listed for sale. In that catalog the CG's were black just like the PA's.

But I've never seen a black CG transformer in real life.

I don't think the chokes were the same.  I have PA-104 chokes and they differ from other UTC chokes.  That PA-309 is rated at 1amp.  Big enough to power any big AM plate mod xmtr.

Fred

The older LS series cubes are made of cast iron, painted black.  The newer versions originally were black, then  charcoal grey, then lighter grey.  The casting is more precision, and it is some kind of lighter weight alloy, looks like pewter.  They call it Hypermalloy. Interestingly, although it is supposed to be a good magnetic shield, it is not attracted by a magnet.

The earlier PA and LS series end bell types also came in two distinct styles.  The earlier ones were more squared off at the corners, the bakelite terminal board covered most of the entire end of the bell, and the terminals were made of some kind of black composition material, like hard rubber.  The later versions were more rounded at the corners, the bakelite terminal board took up less of the end of the casting, and the terminals were white porcelain ceramic.  According to my old catalogues, that change took place about 1938-39.  The change in style from PA to CG was in about 1948-49.

Starting a couple of years after WWII, the variety of transformers listed in the catalogues began to steadily dwindle.  Each year some of the LS series and others were discontinued.  I have a 1958 catalogue that is practically worthless as a reference because the majority of transformers I encounter are no longer listed.

Speaking of UTC, here is where it is today:

http://www.magnetika.com/

They show a few of the old types.

73DG

not much on the website, I guess it is all high end custom to order.

I know I have measured the 'DC' resistance of the secondaries including the taps, but can't find this now.

I was not able to do the primary measurements as are less than 1 Ohm, IIRC, need to be measured with a MilliOhmmeter.

Does anyone have those secondary or primary measurements? Need for Duncan PSUD or LTSpice.

(Hope the PA-309 in the topic didn't get scrapped.)

I wound up with it, no scrappage going on here ;).

When I get time, I'll shoot the windings with ye olde Ohmmeter and report back.

73DG

Clark always came up on some oddball stuff.   I'll give him that.

--Shane
KD6VXI

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...

Wow. I thought I'd entered a time warp.

I had this thread marked to notify me when anyone posts to it.

All of a sudden I started getting emails that someone had posted to a PA-309 thread.

Say what?

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... :o

Those were the days, eh?

73DG

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

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.
 

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.

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 

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.

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. :P

73DG

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 :o
I think the real surprise is that I lifted it 4 times to move it around... It's at least 150++ pounds

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.

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

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

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