Thanks Richard, thanks Garey, Lots of things to try and check, will report back what I find after poking around.
Chuck On Mon, Oct 25, 2010 at 5:15 PM, Richard Knoppow <[email protected]>wrote: > > ----- Original Message ----- From: "Chuck Grandgent" <[email protected]> > To: <[email protected]> > Cc: "drakelist" <[email protected]> > Sent: Monday, October 25, 2010 1:52 PM > Subject: Re: [Drakelist] R4B erratic crystal calibrator > > > Yes, C192 was also part of the Hayseed recapping. >> >> I will check D16. >> >> The erratic operation (better characterized as failing to stay in >> oscillation) was there both before and after the recapping, with the same >> modus operandi. >> >> I do also have a spare 100khz crystal, same form factor, I suppose I could >> try that too. >> >> Chuck, K1OM >> >> On Mon, Oct 25, 2010 at 4:37 PM, Garey Barrell <[email protected]> >> wrote: >> >> Chuck - >>> >>> Does Tom's kit include C192? I think it does. If not .... >>> >>> Also D16. >>> >>> And with the erratic operation, solder joints on C190, etc. Tough places >>> to solder. >>> >>> 73, Garey - K4OAH >>> Glen Allen, VA >>> >>> Drake 2-B, 2-C/2-NT, 4-B, C-Line& >>> TR-4/C Service Supplement CDs >>> <www.k4oah.com> >>> >>> D-16, R-158, R-157 C192, C-190, all appear to be part of a low > voltage supply that feeds the calirator and nothing else. Looking at the > junction of C-190 and the emitter of Q-9 should tell if its working. This is > a half-wave rectifier fed by the 12V filament supply with large filter caps > so the DC out of it should be more than 6 or 7 volts, anyway, it should be > there all the time. The calibrator is switched by lifting a ground at the > source of TIS-34, the oscillator. Its possible the function switch is > intermittant, maybe not likely but its worth cleaning the contacts on S-3 > front. I don't remember if the transistors in this circuit are in sockets or > soldered in, if in sockets wiggle them and if soldered it might be worth > re-flowing the solder. Also, Garey often recommends working any screws that > are used for grounding. This kind of intermittant sounds like a heat problem > but even intermittant switches can be affected by heat. > The output of the calibrator is available at the antenna input to the > receiver and that is a convenient place to check for its presense and for > adjusting the calibration. Also, work the calibrator adjusting capacitor. I > think this is a very unlikely cause but won't hurt anything. > > > -- > Richard Knoppow > Los Angeles > WB6KBL > [email protected] >
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