Lee -
Thanks!! One more tidbit for the database... Bad solder has been a 'fairly' common problem,
nothing like Kenwood, but... :-) I guess that's the price you pay for 'hand-crafted'
electronics, (or 'wave-soldering'!) I suppose over a million solder joints, a few are gonna slip by.
Thanks again.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Lee Zalaznik wrote:
I have a Drake R4B that is having this problem with the frequency shifting, drift and the PTO will
stop oscillating. This happened after I changed the dial lights.
I have cleaned the Yoke and the bar that the Yoke rides on with no change. Also if I pushed on
the end of the PTO it would stop the shifting frequency and become stable for a few days or a week
sometimes.
Today after looking at Ron's web site on fixing a PTO I just removed the PTO cover. I had to take
out a tube 12AX7 to lift the cover off.
After putting the 12AX7 back in, I turned on the radio and started to probe the PTO circuit board
and the most sensitive place was the resistor on top, 6.8K ohm. This resistor is on the left side
of the coil. As I probed the resistor the PTO would stop oscillating with a little more probing
the PTO would start oscillating again.
Next getting out the DVM and probing the resistor when the PTO stopped oscillating there were 10
volts on the ground side of the resistor. Looking closer it looked like the soldering of the
resistor to ground was not complete. It had not flowed on to the ground pad. I also think this
ground pad is one of the grounds for the coils silver mica capacitors.
I heated up the ground side of the resistor and re flowed the solder and made a nice shiney solder
joint that flowed on to the ground pad.
I have heard no more frequency shift or drift or the PTO stop oscillating when i press on the PTO
or wiggle the PTO assembly.
I will do more testing and see if there are any more problems!
Thanks again
Lee KI6OY
P.S. I read each and every post. And thank you to everyone for the PTO
thread, it really helped.
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