[Heath] VF-1

[Glen Zook]

To really tame down the VF-1, replace the 6AU6 with a 6AH6, replace the 0A2 with and 0B2, and then run the VFO from a regulated 150 VDC power supply.  No modifications are needed.


Frankly, NEVER power a VF-1 from either a DX-35 or DX-40.  The power transformer in the DX-35 is grossly overloaded and the power transformer in the DX-40 is just severely overloaded without the extra load of the VF-1.  Build a simple power supply and use the 0A2 removed from the VF-1 to regulate that power supply.


Heath discovered with the original TX-1 Apache VFO that, with a 6AU6, the VFO was not really stable enough for SSB operation with the SB-10 adapter.  Then, the 6AH6 was tried, without any other changes, the VFO really settled down.  Replacing the 6AU6 with a 6AH6 has been recommended with both the Heath VF-1 and the Johnson 122 VFO for at least 50-years.  Going to an 0B2 drops the screen voltage to 108 VDC which helps stabilize the VFO and then supplying 150 regulated VDC helps even more.


The VF-1 also has twice the output of the HG-10 / HG-10B VFO.

 
Glen, K9STH 
Website: http://k9sth.net

      From: Kenneth G. Gordon <kgordon2006 at frontier.com>
 To: Heath at puck.nether.net 
 Sent: Monday, April 8, 2019 3:05 PM
 Subject: Re: [Heath] VF-1
   
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 poorlybuilt, or improperly connected ones. Properly built ones are at least as good as any othergood 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 muchbetter, and drifts less than any HG-10 I have ever owned. I use my VF-1 with my HW-16after 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 severaldifferent 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 recommendyour 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 areJohnsons 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 100Hz/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 areinvestigating why this is so.
Also, the single biggest cause of chirp and drift on 40 and above with the VF-1, especiallywhen using it with the DX-35 or DX-40 or the earlier rigs, is due to RF from the tranmittergetting into the VF-1's cabinet in some way. The cable between the transmitter and VFOmust be 100% shielded, and all incoming leads should be bypassed immediately where theyenter the cabinet. In addition, the contact between the panel and the rest of the box MUSTbe nearly perfect.
   
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