These are not the greatest transmitters high school radio station had something similar. You might try creating a rudimentary oven for crystal use a bimetallic switch if you want authentic otherwise transistor circuit to control heater
Did something similar with my Swan 250 years ago. It was better known as the 'nifty drifty two-fifty'. The oven for vfo system really helped Sent from my iPhone On Jun 21, 2013, at 8:56 AM, Bob Camp <[email protected]> wrote: > Hi > > At that frequency, the crystal is likely some sort of bar cut rather than an > AT. If the transmitter has no oven / heater around the crystal, it will > indeed drift quite a bit. > > Bob > > On Jun 21, 2013, at 12:09 AM, Joseph Gray <[email protected]> wrote: > >> This is not strictly Time Nuts, but it is about a crystal oscillator that >> needs some temperature compensation, or something. Please ignore this >> posting if you like. In fact, so as not to clutter up the list, it would be >> best to email me directly about this. >> >> I have an old AM transmitter that has three 6AL11 compactrons. The crystal >> is a fundamental, cut for 660 KHz. I don't have a schematic for this thing, >> but I believe that one half of one 6AL11 is used for the oscillator. >> >> The problem is, the frequency decreases as the rig warms up. It will >> eventually stabilize, but the final frequency is over 200 Hz low. Not as >> good as it should be. I think the original specification was well under >> half of that. >> >> I have replaced the electrolytic caps. The others are mostly silver/mica >> with a few ceramics. I checked all of the resistors and only found one that >> was out of tolerance (I replaced it).Three NOS tubes were installed. There >> are no tunable components in the oscillator section. Only the output >> section has anything tunable. >> >> I know that there are many Amateurs on the list and I'm sure many know more >> about old tube rigs than I do. Does anyone have a suggestion as to what the >> trouble might be? >> >> Joe Gray >> W5JG >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
