[Heath] VF-1

[Kenneth G. Gordon]

Howard: I have had a lot of respect for the VF-1 since I first used one back in the 1960s.

I'll fill you in on the details later.

I am not sure where the "disrespect" for the VF-1 has come from. Probably from very poorly 
built, or improperly connected ones. Properly built ones are at least as good as any other 
good VFO of the same time period, like the Johnson 122. 

In fact, I prefer it to the later HG-10 for several reasons. For one thing, my VF-1 keys much 
better, and drifts less than any HG-10 I have ever owned. I use my VF-1 with my HW-16 
after having modified it for grid-block keying, which is a very simple process.

Recently, Dave Ishmael W6VVL and I have been running a bunch of drift-tests on several 
different VF-1s, and have learned a lot about them.

As soon as I can, I'll send you what we learned, but in the meantime, I would recommend 
your putting yours back to original.

Dave had an FET version, which he had built, and it never did work very well. He recently 
"converted" it back to original.

You will have to "sort" any 6AU6s you own to choose one that keys best and drifts least.

A couple of questions concerning yours: 1) does it have the early copper-plated chassis? 2) 
can you tell if the tuning cap is bolted together, or soldered together?

The bolted caps were Cardwells, and were used in the early ones. The soldered caps are 
Johnsons and aren't quite as good as the Cardwells, but were used in all the later ones.

My present VF-1 is an excellent VFO, although it takes a while to warm up.

On 40 meters, tested recently, it drifted less than 83 Hz. in an hour after it was warmed up. 
On 160, it drifted 17 Hz in an hour of steady output.

I don't consider that too bad. Remember the old advertising blurb about, "Less than 100 
Hz/hour drift after warm-up!"? Our VF-1s meet that easily.

BTW, of all those we have tested, warm-up drift is far better on 160 than on 40. We are 
investigating why this is so.

Also, the single biggest cause of chirp and drift on 40 and above with the VF-1, especially 
when using it with the DX-35 or DX-40 or the earlier rigs, is due to RF from the tranmitter 
getting into the VF-1's cabinet in some way. The cable between the transmitter and VFO 
must be 100% shielded, and all incoming leads should be bypassed immediately where they 
enter the cabinet. In addition, the contact between the panel and the rest of the box MUST 
be nearly perfect.

Ken W7EKB
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