UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Bazz4CQJ · 26th Jan 2018, 5:27 pm

6Tanuki has nailed it.

Back in Pye Vanguard days I built an 11MHz VFO for use on the receiver. Of course, its output and its drift were multiplied by a factor of 12 at the final frequency. Also, the set would start at room temperature and head to somewhere well over 40°C, and then heat and cool further depending on whether it was on transmit or receive. I eventually got a tolerable outcome, but only after spending some time time (several days) playing at being "Tempco Man"!

.

My recollection is that there are still some neg temp coef caps around in the form of NOS tubular ceramics and polystyrenes too. Partridge electronics could be a place to try.

Torroids....really the way to go for a stable oscillator, why so

?

B

26th Jan 2018, 5:27 pm	#7
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Compensating for VFO drift 6Tanuki has nailed it. Back in Pye Vanguard days I built an 11MHz VFO for use on the receiver. Of course, its output and its drift were multiplied by a factor of 12 at the final frequency. Also, the set would start at room temperature and head to somewhere well over 40°C, and then heat and cool further depending on whether it was on transmit or receive. I eventually got a tolerable outcome, but only after spending some time time (several days) playing at being "Tempco Man"! . My recollection is that there are still some neg temp coef caps around in the form of NOS tubular ceramics and polystyrenes too. Partridge electronics could be a place to try. Torroids....really the way to go for a stable oscillator, why so ? B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. Last edited by Bazz4CQJ; 26th Jan 2018 at 5:34 pm.