[Central-Electronics] CE20 Documentation

[Jim Candela]

Jon,

    You could hook up the Huff & Puff to the 9 Mhz oscillator, and use your DDS VFO to replace the BC-458. Then again, the crystals I tried tended to move suddenly during the warm up period. Sometimes the frequency shift went up, sometimes down. Any sudden change might unlock the H&P. Regulating the filament voltage to the 6U8 might help.

  Yes the Lakeshore Bandhopper VFO is rare. I was fortunate to find one. Still these things do need a good going over from age and neglect. The dial paint peels off, and the window turns yellow and eventually falls off. I have a pretty fair digital image of the dial, an have restored two dials, one white over black, and the other black over white. One was for Doc Kalsa on this forum, an his came out pretty good. Still drifted about 300 hz first hour. Mine was twice that until I added the Cumbria X-Lock Huff an Puff. Now it stays locked within +/- 10 Hz after turned on 1 minute and beyond. I had to regulate the VFO tube filament voltage, and switched from a 6CB6 to a 6BH6 to save on filament draw since my 7806 was getting pretty warm.

I lost my webspace, but here is a link to what I did:

http://www.elforum.ro/viewtopic.php?f=217&t=88487


Google can translate the language, since this is Romanian. :-)

Jim
WD5JKO

________________________________
From: k6jek <k6jek at comcast.net>
To: Jim Candela <jcandela at prodigy.net>
Cc: "central-electronics at mailman.qth.net" <central-electronics at mailman.qth.net>
Sent: Saturday, August 27, 2011 10:38 AM
Subject: Re: [Central-Electronics] CE20 Documentation

I've used my 100V in conversations with guys on modern stuff.  I gave up on the 100V VFO and plugged in an external DDS VFO.  This works!  The two (count em, 1,2) oscillators in the 100V seem to be stable enough that I get no complaints and that baby has wonderful audio.  I did have to fight a long, hard fight to get the opposite sideband suppression up to snuff but now I happily use the 100V talking with guys on their 60 year newer equipment.

I tried the same thing with the 20A after discovering that the CE-458 VFO drifts quite a bit if you don't leave it on all the time.  I have a huff and puff kit which I have vague plans to install.  In the meantime, I figured I would be fine with the external DDS based VFO.  No!  Unlike the 100V, the internal oscillator (only 1) is a drifter.  Too bad.  The 20A has one huge advantage over the 100V, though.  It doesn't weigh 70 pounds

Thanks for the link. I didn't know about it. The wiring diagram like the one on that site was a great help getting mine on the air.  CE made a lot of changes when the 20A had been out for just three months.  Well mine is an early one and the schematics you find everywhere don't match it.   I was puzzled until I saw the wiring diagram.

Jon

PS: The Lakeshore VFO's are rare, aren't they.


On Aug 27, 2011, at 5:26 AM, Jim Candela wrote:

> 
> 
> The following link has some great information on the 20A. So check it out and download any files that you might want to keep.
> 
> 
> http://frank.pocnet.net/instruments/CentralElectronics/20A/20A.html
> 
> 
> Jim
> WD5JKO
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