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Title: R-388 51J Power Tranny Spec/Replacement?? Post by: WBear2GCR on April 01, 2008, 03:39:32 PM 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 Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: W1ATR on April 07, 2008, 06:14:52 PM 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. Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: W1ATR on April 07, 2008, 06:26:52 PM 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? Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: WA5VGO on April 07, 2008, 06:27:40 PM 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 Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: WZ1M on April 08, 2008, 03:07:08 AM Have it rewound.
Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: N3DRB The Derb on April 08, 2008, 06:28:20 AM B+ only 90 ma? That seems kinda scroteless to me. ???
Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: W1ATR on April 08, 2008, 11:40:11 AM 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. Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: WA5VGO on April 08, 2008, 06:10:28 PM My numbers came from a Peter W. Dahl catalog. Maybe his is stouter than the original?
Darrell Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: N3DRB The Derb on April 09, 2008, 03:19:06 PM 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.
Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: WBear2GCR on April 10, 2008, 12:07:36 AM 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! Title: Re: R-388 51J Power Tranny Spec/Replacement?? Post by: w3jn on April 10, 2008, 07:06:06 AM The highest current draw will be when there's no, or a weak, signal - AVC full off. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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. |