Take a look at the Central Electronics VFO made from an ARCr/BCxxx Transmitter. Problem was solved a good while ago.
R
From: milsurplus-bounces@mailman.qth.net <milsurplus-bounces@mailman.qth.net> On Behalf Of Mack McCormick
Sent: Tuesday, November 8, 2022 10:41 AM
To: milsurplus@mailman.qth.net
Subject: [Milsurplus] Advice Please: Frequency stabilizing a 80M ARC-5 transmitter
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.