MOD XFMR - what is it from? TF1RX21KA / Topp 263622 / UTC PA-3252

[Opcom]

I am trying to find out what this mod xfmr is from. Military I suppose, but from what?

pri:
3800 Ohm CT, 100mA DC BAL. WV 1300V.
sec:
0-1800-2250-2700 Ohm 250 mA DC WV 1200V. (4 terminals, a tapped winding)

nomenclature:
AUDIO TRANSFORMER
TF1RX21KA
COMMUNICATIONS DIVISIONT TOPP MANUFACTURING CO.
TOPP #263622
300-4000 CPS +/- 0.33 DB
POWER LEVEL 70W MAX
MAX. ALT. 10,000 FEET
UTC PAC. DIV. PA-3252

I have to wonder if the many taps there on the secondary are for driver modulation as well as PA screen mod, or maybe one for audio feedback.

Can anyone help please?

[W3RSW]

Cute little thing.
Ought to be good for, say, a pair of 807's modulated by a pair.
Maybe even a pair of 812's mod. by a pair of 811's. At 1000 volts they ought to last forever.

[KM1H]

The secondary is all one winding tapped for different RF loads. Its not military and may have been used in marine (fishing boats), public safety, or any other similar power TX.

Carl
KM1H

[k4kyv]

The frequency response MAY be better than the nominal 300-4000~ as stamped on the case.  Sometimes transformers are far better than what was called for in the military contract, but they label it per the contracted specifications. I have seen transformers with such ratings that actually approached broadcast quality.  But I have seen others that just barely made the nominal specs.

[KM1H]

With the spec listed, 300-4000 CPS +/- 0.33 DB, I think its pretty obvious that the response extends in both directions.

Without a FSN its doubtful it is military. The part # are strictly commercial.

Carl
KM1H

[Opcom]

It's the "TF1RX21KA" that made me think it is military. I have seen this on many military transformers, it seems to be a type number, trancending manufacturers. It is cute allright. I like it very much. Makes me want to build a little TX. So many parts, so little time.

[N2DTS]

Do normal (non military) transformers usually have altitude ratings on them?
I have seen a lot of 10,000 foot ratings which is very low for most aircraft!

Brett

[Opcom]

Sealed units often do have the rating. I'm pretty sure this one is ground oir sea based, due to it being much heavier than a similar aircraft-type (618S-1 mod xfmr for instance)

[KM1H]

The 10000' rating is double talk for land or sea use only. Most light aircraft run way less power.

Ive seen that TF prefix on a lot of commercial gear and the UTC PAC. DIV. PA-3252 is not military. That doesnt leave out numerous government agencies such as FAA who buy their own equipment.

Carl
KM1H

[W3RSW]

I think your right on the altitude rating.  Most of my mil. spec. WWII potted transformers for aircraft use are rated at "50,000 ft."  I have one in my 813 rig used as a bias supply transformer.