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

[Jim Candela]

Hi All,

    I want to clarify something I stated earlier. Yes I did buy and 
construct a Jim Haggerty DDS VFO, but that was from a QST article back in I 
think 2002. The DDS VFO that Jim has on the market today is not the same 
one, and after a quick look it seems that the design has evolved since that 
first kit. My correspondence with Jim H. back when I bought the kit was 
excellent, and the kit worked upon the first power up.

   I still hold my preference towards using the original vacuum tube VFO for 
the look and feel of using a vintage VFO. A compromise I might make is to 
put the DDS VFO into a CE BC-458 VFO where the VFO just runs the usual 5-5.6 
Mhz and then the 1625 acts as a buffer and frequency multiplier just like 
the CE company designed it. This would require some major surgery to the 
BC-458 in order to pull it off. The 1626 rube and oscillator tank circuit 
would need to be removed, and the front panel would need to have some major 
changes.

   I would be happy to expand upon my Huff & Puff experience with the 
Lakeshore Bandmaster VFO and recommend what it mike take to add the Huff & 
Puff approach to the BC-458. This would be similar but the BC-458 has a 
different set of circumstances to overcome. The Huff & Puff approach can be 
bought with a PIC (programmable IC) in kit form, or it can be done with just 
a few digital IC's. Just Google "Huff & Puff VFO".

Regards,
Jim
WD5JKO


----- Original Message ----- 
From: "Jim Candela" <jcandela at prodigy.net>
To: "Bob Heil" <bob at heilsound.com>; <central-electronics at mailman.qth.net>
Sent: Sunday, January 25, 2009 12:26 PM
Subject: Re: [Central-Electronics] 10B and 20A BC-458 VFO issues


> 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!
>
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