[ARC5] SSB Transceiver from a BC-453

[Christopher Bowne]

40 meters with the 9 Mc base band is a little more complicated than 80/75 and 20.  For those bands your either sum the 9 Mc with a 5+ Mc VFO to get 14+ Mc for 20, or subtract a 5+ Mc signal from 9 Mc to get 4-Mc for 75/80.

40 meters requires subtracting the 9 Mc base band from a  16 to 16.3 Mc signal to get 7 to 7.3 Mc.  In the Central Electronics VFO 458, built around the 5.3 to 7 Mc SCR-274 BC-458 Command Set Transmitter, a multiplier stage is used to generate the 
3rd harmonic of 5.333 to 5.433 Mc. Because of the multiplication, the 40 meter dial on the CE VFO 458 has a much smaller band spread than 80/75 or 20.  The CE conversion removes some plates from the original command set MO variable cap for bandspreading, you really have to grind a lot of coffee to move from one end of 80/75 or 20 to the other.  40 meters OTOH tunes very fast.

Chris AJ1G Stonington CT

CE20A and 600L paired with an RTL SDR running on an iMac - My Back to the Future HF Rig!

Sent from my iPhone

> On Jan 29, 2020, at 22:55, Dan Osborne <wb5afy at wb5afy.net> wrote:
> 
> Bob - I have one of these that is setup for switching between 80M and 20M - but have not seen a unit
> setup for 40m..
> 
> W5AFY
> 
>> On 1/29/2020 2:44 PM, Robert Nickels wrote:
>> I suspect many of you have seen the documentation about this conversion that was designed by Ernie Mason W6IQY and documented by Ed Marriner W6BLZ in 1961.   I don't want to get into the ethics of modifying command sets - it was done then for reasons that made good sense at the time.
>> 
>> What I would like to know is - has anyone ever seen one of these 40 meter transceivers in person?    Or possibly knows of any that still exist?
>> 
>> 73, Bob W9RAN
>> 
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> 
> -- 
> W5AFY (ex WB5AFY) EM04id 972-839-6992 cell
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