[ARC5] SSB Transceiver from a BC-453

[D C _Mac_ Macdonald]

I built one of those back in 1962, but think I used the BC-457 (4.0 - 5.3) for the VFO.  With the SSB signal generated at 9.0 MHz, 80/75 meters would cover 4.0 to 3.7 MHz using VFO of 5.0 - 5.3 MHz using down (subtractive) mixing.  20 meter coverage of 14.0 to 14.3 MHz used up (additive) mixing with the same VFO 5.0 to 5.3 MHz coverage.  In those days, only 14.2 to 14.3 MHz was open to voice signals in the 20 meter band.

I never heard of an SSB rig built using a "command set" receiver.

73 de Mac, K2GKK/5​
Since 30 Nov 1953​
Oklahoma City, OK​
USAF, Retired ('61-'81)​
FAA, Retired ('94-'10)​

________________________________
From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> on behalf of Christopher Bowne <aj1g at sbcglobal.net>
Sent: Thursday, January 30, 2020 18:37
To: wb5afy at wb5afy.net <wb5afy at wb5afy.net>
Cc: ARC5 at mailman.qth.net <ARC5 at mailman.qth.net>
Subject: Re: [ARC5] SSB Transceiver from a BC-453

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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