Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Well the only thing I can think of to try at this point would be to
disconnect one end of the tubular TC cap. The frequency will shift, and
the temperature compensation will be messed up, but at least you could
then increase the voltage to 10V and see if it still FMs. If that cap
does indeed prove to be the problem, you can read the value by
deciphering the dot code. I don't believe the TC is coded, so you could
try an NP0 of the proper value and see what the TC does. Then depending
upon your patience level try an N750, N330 or N90 and see what happens.
Have you checked DC potentials when it is FMing? Perhaps you have a
noisy resistor. They ARE carbon comps, and in particular the 1M Gate
resistor R111 could cause some mischief. Do you have some cooler
spray? Or heat gun/solder iron to selectively heat passives?
There's absolutely no reason you should have to add an amplifier to a
proven design with 50,000+ examples on the hoof!! :-)
73, Garey - K4OAH
Glen Allen, VA
Hubert ROTH wrote:
"Hubert ROTH" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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I tried a J310 a BF256C always the same. Oscillator is the BF256C
Buffer amp is a 2N3404 now.
About the caps I agree but as I get over 9V signals turns very dirty
on the analyzer and you have FM sidebands over more than 100Hz!!
Interresting case isn't it?
I stick with the 8V and used a MAR1 amp to incease the PTO level but
it is not enough. I've breadborded an amp with an OPA603 witch has
more gain and geater output swing. I try this tomorrow.
It breaks a bit my heart because I prefer vintage equipment running as
they were designed once.
Thank you for scratching your head with me
Hubert
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