I had a similar experience working on a Gates Broadcast transmitter, a BC-1J. This transmitter used two audio driver transformers driving two pairs of 6B4G's. I had one of the driver transformers go bad. I had two Identical modulation transformers that I replaced them with. After connecting and running the transmitter , all meter indications indicated that it was working as normal, however it was modulating a very low percentage. After many hours of work, I reversed the leads connected to the output of the two driver transformers, and my modulation came back to normal.
Don W5FFK/Kansas On Mon, 19 Feb 2007 21:54:06 -0600 "Joe Walden" <[EMAIL PROTECTED]> writes: > >From Joe w5jdy in Okla. My experience with a modulator. I > replaced the > audio drive transformer in a Viking II (the one feeding the grids of > the > final modulator tubes) with a brand new in the box Hammond > Transformer from > Antique Radio in Tempe Arizona... I had mod current but distorted > audio and > a real low modulation per-centage. Even the dummy load light bulb > dimmed on > mod peaks. > After many,many moons,the trouble > was located. The NIB Driver transformer was wired wrong inside. > It had > two individual windings for the grids > and they were phased wrong inside the transformer. It was a > nightmare... > All > voltages and currents were as the manual stated and I had good audio > from > each grid to ground but hardly any audio from grid to grid. As I > say the > mod tubes > were bucking each other... It was running Push-Push instead of > Push-Pull? > I emailed Hammond and they sent me another NIB > same part number transformer NO Chg.and the trouble was totally > corrected... > 90% Plus Modulation NO distortion.... If you replaced any new > parts,look > there first??? w5jdy Joe in Okla..... > > > > > ______________________________________________________________ > AMRadio mailing list > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Partner Website: http://www.amfone.net > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > To unsubscribe, send an email to [EMAIL PROTECTED] > with > the word unsubscribe in the message body. > > ______________________________________________________________ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
