[Central-Electronics] 10B and 20A BC-458 VFO issues

[Jim Candela]

Bob,

    I bought one of those DDS VFO kits from Jim. I chose the range of 2.5 - 
12.5 Mhz. I built it up and made a temporary lashup adding an amplifier to 
increase the VFO injection to my 20A to about 8 volts peak. Remember the 
stock 20A VFO output is straight, doubled, and tripled depending on the band 
chosen, and for 10 meters the optional VFO add on heterodynes the VFO output 
against a crystal for 10 coverage.

    The thing worked very well with some limitations. Every time you power 
it down the DDS reverts back to the minimum frequency, in my case 2.5 Mhz. 
So to get back to a given ham band you need to make a chart of VFO frequency 
desired versus DDS display setting for every transmit frequency, and dial 
that number in every time. It won't just stay there.

   Also keep in mind that the 20A 9 Mhz crystal oscillator drifts about 100 
Hz over the first hour of warm up. A stable VFO won't fix that problem.

  I prefer stabilizing the original VFO with a Huff & Puff circuit. Works 
very well for me with the Lakeshore Bandmaster VFO.

Never packaged up the DDS VFO. Sitting in a shoe box waiting for a rainy 
day...

Regards,
Jim
WD5JKO
----- Original Message ----- 
From: "Bob Heil" <bob at heilsound.com>
To: "Jim candela" <jcandela at prodigy.net>; 
<central-electronics at mailman.qth.net>
Sent: Sunday, January 25, 2009 11:00 AM
Subject: [Central-Electronics] 10B and 20A BC-458 VFO issues


> Hello Everyone and Happy New Year !
>
> Has anyone successful used Jim Hagerty  www.WA1FFL.com digital VFO on the 
> 20A?  Seems like a logical next step to stabilize the VFO of this 
> fantastic piece of technology.
>
> Any experience within the Central Electronics group?
>
> Regards,
> BOB HEIL, K9EID
> CE since 1958 and still glowing!