[Drake] Drake R4C - Unstable VFO

[Jim Garland]

Bob, usually your symptom can be cured by cleaning the spring loaded wiper
that grounds the PTO shaft. (No need to remove the PTO to do this.)
However, I have a T4XC whose PTO jumps around every few minutes, and I've
not been able to fix the problem. I suspect a bad cap inside the PTO unit.
73,
Jim W8ZR

> -----Original Message-----
> From: drake-bounces at mailman.qth.net [mailto:drake-bounces at mailman.qth.net]
On
> Behalf Of Robert Wood
> Sent: Thursday, December 30, 2010 1:24 PM
> To: drake at mailman.qth.net
> Subject: [Drake] Drake R4C - Unstable VFO
> 
> Hello Drake Techies,
> 
> I have a possible PTO issue with my R4C.  When listening to CW on any
band, the
> signal is not stable (tone jumps around) intermittently.  I do not
encounter the
> issue when switching to my TX4C PTO.  When using the T4XC PTO I can work
other
> stations with no problems :).
> 
> At this juncture, here are the steps I have taken within the R4C:
> 
> 1. Cleaned all of the vacuum tube sockets and pins (deoxit)
> 2. Cleaned all of the switch contacts (deoxit)
> 3. Swapped 6HS6s (Premix Tube with the 1st Mix tube) no change
> 4. Replaced the two electrolytic capacitors (C163, and C163)in the 150V
power
> supply section. (I thought I noticed the voltage fluctuating so went ahead
and
> upgraded the caps)
> 5.  Tightened the VXO mounting screws.
> 
> I am thinking about swapping the PTOs between the units to see what
happens, but
> before I do I wanted to get other suggestions?  I really appreciate any
help.
> 
> Thank you very much,
> 
> Bob
> K5MBA
> 
> 
> 
> ______________________________________________________________
> Drake mailing list
> Home: http://mailman.qth.net/mailman/listinfo/drake
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Drake at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html