Hi Richard, I once went so far as to even contemplate the logistics of installing a small pilot bulb inside the PTO can to act as a "heater," with hopes that it might afford the circuitry a modicum of thermal stability (much like a crystal oven, if you will)...
The original plan was to have a feedthrough capacitor mounted in the can, with the bulb attached to it & the inside of the shield---the voltage to light it would have come from a "tap" to a convenient tube heater pin. I never followed through on it, because of the fact that so many thousands of other Drake PTOs were apparently not ailing from what was afflicting mine---so why would mine be different...? Besides, space inside that PTO can is at a premium, & I was worried about the detrimental effects all the extra wiring of the bulb might have upon the PTO's function in terms of calibration, linearity, etc. ~73~ de Eddy VE3CUI - VE3XZ *********************************************************************************************************************** On 2011-07-29, at 1:17 PM, Richard Knoppow wrote: > > ----- Original Message ----- From: "Eddy Swynar" <[email protected]> > To: "Curt Nixon" <[email protected]> > Cc: <[email protected]> > Sent: Friday, July 29, 2011 9:54 AM > Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors (entirely) > > I have so far not had this problem any of my drake gear so I don't have > direct experience trouble shooting it. Since so much of the PTO has been > investigated without success I wonder if the problem could be external to the > PTO. Either another oscillator or something after the PTO that is affecting > it. I have no specific suggestions other than monitoring the PTO output with > a receiver to make sure that is what is varying. Probably so but its worth > being sure. Also, if it seems to be heat sensitive it may be possible to use > a low power soldering iron to selectively heat compenents. I find a heat gun > is too diffuse, it heats everything. Freeze mist is evidently hard to find > now (I think it was Freon) but canned air works if the can is held upside > down. > Have you examined the coil to see if there is a loose turn? I know this is > grasping at straws. > Everything else I can think of has already been tried. It is so > frustrating to trouble shoot something where all the parts are good but the > thing doesn't work. > > > -- > Richard Knoppow > Los Angeles > WB6KBL > [email protected] _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
