R-388 51J Power Tranny Spec/Replacement??

[WBear2GCR]

Anyone have or know the spec on the power tranny for the R-388/51J??

The one in my R-388 let out some smoke today... the filter cap seems ok, and the rectifier seems ok, so it must just be hot and toasty inside. I think I remember it doing the same trick several years ago.

Looks like I need to replace it. Or will need to replace it?

Anyhow, I can figure the 6.3vac winding spec, the question is what is the B+ winding's AC volt spec and the current spec for it?

OR, anyone GOT ONE??

(also looking for a BFO can with innards...)

              _-_-bear

[W1ATR]

Real nice. I've been busier than a one armed paper hanger these past few weeks, so I missed this one all together.

Seems like the month for 388 trannies to go out. (Remember my other post regarding the leakout ordeal?)

I'll look thru my stuff, I should have the paper work for this beast.

[W1ATR]

Ok, lemmee see if I can get this off the paper and onto the intraweb without screwing it up, lol.

terminals'

11
10(CT)          700v @90mA
9

5
6                   5V @ 2A (fil for 5v4 and takes off thru L122 to do some moonlighting somewhere else)

7(goes right to ground)
8                                    6.3 @ 5A

How'd I do?

[WA5VGO]

Pr) 115/230 VAC
S1) 700 VCT @ 200 MA CCS
S2) 5.0 VAC @ 2A CCS
S3) 6.3 VAC @ 7 A CCS

I'll bet Hammond has something that will work, but I don't know about the mechanical details.

Good Luck.

Darrell, WA5VGO

[WZ1M]

Have it rewound.

[N3DRB The Derb]

B+ only 90 ma? That seems kinda scroteless to me. 

[W1ATR]

B+ only 90 ma? That seems kinda scroteless to me. 

Yeah, seems a little light, don't it. They spec it at 90mA right on the print. Darrell said 200mA which seems more inline.

Maybe they mean 90mA each side of ct.

[WA5VGO]

My numbers came from a Peter W. Dahl catalog. Maybe his is stouter than the original?

Darrell

[N3DRB The Derb]

there's no way it's 90 ma. That would barely take care of the needs of the audio output tube, never mind the rest of the radio.

[WBear2GCR]

Mine's running ~630vac under load as far as I can tell.
Might be a clear indication of some shorted turns.
Might be normal?

Also I'm seeing only ~230vdc, which seems low. Dunno exactly what's going on yet.

700v @ 0.2a = 140watts... quite enough for a receiver.
Audio out is only a few watts full bore. So the rest of the toobes are just sitting around doing not much current in RF/IF??

I put a small (1 3/4" sq.) 12vdc computer fan running from 6.3vac bridge rectified and filtered blowing on the iron and it seems cooler for now.

Still concerned about it.

Thanks for the numbers guys!

                    _-_-Wooly Bear Two Grote Clusters Really!

[w3jn]

The highest current draw will be when there's no, or a weak, signal - AVC full off.

The 6BA6s draw about 15 mA each (plate+screen) when idling in Class A according to my handy Generous Erectric Toob Manwell.  As AVC voltage increases and the toobs go towards cutoff, current will decrease.