[AMRadio] DX-100


George Pritchard gpritchard at comtechpst.com
Mon Jul 19 08:45:31 EDT 2004


Replace the circuit with this modification. Works well with my DX-100. The
carbon element pot is smooth and will "never" fail since it sees low
current. Also... Spread out the turns on the 10/15 meter 6146 grid coil pair
to get lots more grid current at 10/15 meters. If the coil turns are not
spread out a bit, the Q is very low.
http://www.amwindow.org/tech/htm/drivepot.htm
Good luck,
George AB2KC

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Edward B Richards
Sent: Sunday, July 18, 2004 7:58 PM
To: amradio at mailman.qth.net
Subject: Re: [AMRadio] DX-100


Another thought: 

Maybe the driver is not seeing the oscillator and breaks into oscillation at
max gain. Check that the oscillator is working. Pull the oscillator tube and
see if it does the same thing. Be sure the VFO is outputting several volts
at the correct frequency, that the crystal/VFO switch is in the VFO position
(don't ask me how I know), That the crystal/VFO switch is working. Check
that you have adequate drive to the driver grid.  Good luck.

73, Ed Richards K6UUZ

On Sun, 18 Jul 2004 16:19:43 -0700 Edward B Richards <zuu6k at juno.com>
writes:
> Hi Gary, et al:
> 
> This is the way an oscillator acts. Check to be sure the VFO is not
> going
> in and out of oscillation. It is also possible that the driver or PA 
> is
> going in and out of oscillation. Good luck.
> 
> 73, Ed Richards K6UUZ
> 
> 
> On Sun, 18 Jul 2004 18:22:20 -0400 "Gary Poland"
> <gpoland1 at cinci.rr.com>
> writes:
> > I have tried a new 12BY7A and 5763 with no change. With the DX100
> in
> > CW and
> > the PLATE switch off...I have to run the DRIVE pot fully CW before
> 
> > the GRID
> > current shows on the meter. Once peaked with the DRIVER TUNE and
> set
> > at 5 ma
> > all is well until I run the DRIVE pot back down CCW. Then running
> it
> > back up
> > results in no grid current until I max out the pot again. This
> will
> > also
> > occur if I move the DRIVER capacitor off peak. I always have to
> max
> > out the
> > DRIVE pot Really screwy HI HI.
> > 
> > 73, Gary
> > 
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