[AMRadio] Gates BC1-H Info wanted

pete zilliox pete at zilliox.net
Mon Apr 20 16:02:31 EDT 2015

I'm trying to bring up a Gates BC1-H, first on 1240 KHz then I'll move it
to 75 meters.
I'm having trouble getting it to properly load up and get neutralized.  I'm
using an oscilloscope on the modulation monitor coil tap, and I'm
experiencing a severely distorted RF Driver waveform with the RF Final
Stage (833s) HV off.   The low level oscillator/buffer signal going to the
pair of 807 drivers looks clean.  But there's a distorted waveform from the
807 RF drivers makes it difficult to pre-tune the final tank circuit and do
the neutralization adjustment (with the HV off as per the manual
instructions for tuning the transmitter).  I've swapped out the 807 driver
tubes and have the same problem.  I suspect either the bias supply in the
RF Driver section or a Final Amp bias circuit problem.  It would help if I
knew what voltages were supposed to be there.  So, I'm looking for a tube
voltage chart.  The manual I have has no tube pin voltage charts.   What
else would cause the RF Driver to distort the signal?  Any help out there
would be appreciated.

Huntington Beach

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