Tell the SDR folks where they can go.
Of course having a freq counter to show you where you're at is probably the cheapest and easiest.
Otherwise, you may try something like the following : http://www.hanssummers.com/images/stories/library/afc.pdf

73
de WA4AM
Mark

On Tuesday, November 8, 2022 at 10:41:48 AM EST, Mack McCormick <[email protected]> wrote:


I have an ARC-5 transmitter that I am using as a VFO for the BC-375 to prevent FMing from the BC-375 MOPA oscillator/PA. 

The ARC-5 exciter is working great except for frequency stability. The peak carrier frequency starts about 1 kc low and after about 1 minute is about 1 kc high. Not really a big deal except it drives the SDR folks crazy when I'm on an AM net. 

The 1626 oscillator is exceptionally well regulated using a FET in the external power supply. It is rock solid. 

Do you have other ideas on how I might further improve frequency stability? I built a crystal oscillator but it does not have enough drive using a 12A6 vacuum tube to drive the 1625's above about 5 watts. I'm still troubleshooting this circuit. 

I need about 20 watts out of the 1625s. 

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