...I later experienced band switch contact issues with that VF-1, and it was more like a spread spectrum exciter. Off to the dump that POS went.....
Recently, I have seen VF-1's go for big bux amongst the collectors. I wouldn't throw one away nowadays.
One problem I discovered with my VF-1 was thermal drift. I took it apart and noticed the construction; the slug tuned coils are mounted on one wall of the oscillator subchassis, and the slugs and their bushings are mounted on the opposite wall. So as the temperature varies, the whole compartment expands and contracts, and moves the slugs in and out of the coils. No wonder the things drift! Then I noticed the insides of a DX-100, which has a nearly identical VFO. The coils and slugs are mounted on the same piece of chassis panel.
So I remounted the coils in mine to the same side of the subassembly. It was easy - just drill a couple of mounting holes on either side of the original coil slug bushings (with the slugs removed during the process). I had to slightly re-route some of the wiring, but it was easy to hook everything back up, and it worked FB once reassembled. It didn't stop the drift entirely, but reduced it by at least 90%. It was nice and stable on 160/80, but was still drifty on the 40m. range.
I ran the VF-1 off a CVT. It too, drifted with slight changes in fil. voltage. I think both the VF-1 and Collins PTO's use a 6AU6 as oscillator tube. My "silent" Sola beats fooling around swapping tubes. I suspect even a good tube would eventually become drifty with age.
Don k4kyv
