[Drake] TR-4 voltage question

[ltaft at charter.net]

Thanks for your kind words the other day.  They made it to the reflector.

The freq jump could be the carrier osc as that and the PTO determine the 80 and 20 meter output frequency.  I have seen more troubles with xtals than the PTO.  

Wave your soldering iron around the carrier xtal to see if it jumps.  Should drift smoothly.  I've thought of using cold spray on the xtal but that may be too much of a thermal shock for the quartz.  Looking at the xtal osc with my spectrum analyzer has shown some weird signals that go away when a new xtal is installed.  

Maybe a shot of cold spray into the PTO can would be an interesting test too.  Check the Vcc voltage to the PTO since that is derived from one of the high voltage lines.  The resistors have been known to go bad.  Also the Zener diode in the PTO can go too.
 
I have repaired a couple of PTOs without destroying the calibration but that was more luck than skill.

73, Larry  K2LT
drakerepair.com
800-687-9161

> 
> From: "Richard Peterson" <wb5nen at hotmail.com>
> Date: 2005/12/12 Mon PM 02:59:33 WET
> To: ltaft at charter.net
> Subject: Re: Re: [Drake] TR-4 voltage question
> 
> 
> Larry,
> 
> Sometimes this Drake mail reflector won't accept my postings and I have not 
> figured out why .... it's kinda frustrating.
> 
> But I hope you did get my last message sent to you directly (and copied to 
> the reflector) that the tube replacement fixed the bridge. And now that I 
> think about it, that is not really very surprising. Bridges are "touchy."
> 
> Bit by bit, the TR-4 is coming back to life. My next challenge: the PTO 
> jumps up or down a couple of kc during warmup ... I will be putting a 
> counter on the PTO tonight to see if it's that stage or soemthing else. I am 
> almost postive it is, since it does it on 80 (no crystal oscillator) and on 
> 40 (mixed with a crystal). I wonder if it is electrical or mechanical (dried 
> lubricant)? Don't know.
> 
> But it really is a nice radio. I plan to keep it. I am the 2nd owner.
> 
> Richard
> WB5NEN
> 
>