[ARC5] Stable 2.0 MHz VFO.

[Kenneth G. Gordon]

Hello, John:

Yes. Building a VFO with the stability you mentioned in your e-mail 
for 2.0 MHz is not really much of a problem. The solution has been 
available since the late 1940s.

In fact, the Heathkit VF-1, when properly built or rebuilt, is at 
least that stable at 160 meters. It outputs over the range 1.7 to 2.0 
MHz.

There was a solid-state version of the device your require published 
in a recent issue of Electric Radio magazine, if you wanted to go 
that route.

My Heathkit SB and HW "all-banders" are at least that stable and 
their VFOs operate at 5.0 MHz. When warmed up, they stay within a few 
Hz on all bands. My HW-101 (homebuilt solid-state) drifts back and 
forth about 2 Hz, and about 50 Hz from dead cold to warmed up. My SB-
301 and SB-401 (tube based) are about the same. My SB-102 (solid-
state) drifts even less.

There are at least two "secrets" to building such a device: 1) a well-
wound coil using fairly heavy solid wire on a ceramic form, and 2) a 
really good double-bearing tuning capacitor. You should also be very 
careful of what kind of fixed capacitors you use in the circuit also.

You might want to look at the Vackar circuit I have up on my website. 
It is unusually stable.

http://www.w7ekb.com/glowbugs/VFOs/vackar_vfo.html

Ken Gordon W7EKB