[MRCA] GF 11 transmitter

[B. Smith]

That looks like a "SideTone" switch to me.
Z

On 7/18/2023 6:46 PM, MARK DORNEY via MRCA wrote:
>  Pictures of the sideband switch on the GF-11 transmitter:
>
>
> Mark D.
> WW2RDO
>
> “In matters of style, float with the current. In matters of Principle, 
> stand like a rock. “.   -   Thomas Jefferson
>
> Sent from my iPhone
>
>> On Jul 18, 2023, at 5:01 PM, Christopher Bowne <aj1g at sbcglobal.net> 
>> wrote:
>>
>>  To paraphrase a famous line from the movie Casablanca, I’m shocked 
>> Mark, I
>> tell you shocked!  The GF-11 is an early 1930s low power command set 
>> with a two tube MOPA RF arrangement , and a pair or type small type 
>> 10 triodes.  Perhaps yours has been modified use as  a phasing type 
>> single sideband exciter in the early days of amateur SSB in the late 
>> 1940s-early 1950s.  In that case I would expect there would be 
>> evidence of considerable modification, including a phased shift 
>> network and a  balanced modulator and a pair of carrier null 
>> potentiometers. Or perhaps it’s just a dummy switch added as a joke 
>> or prank back in the day.
>>
>> That said, MOPA sets like the GF-11 can in fact transmit a signal 
>> that has one sideband that contains significantly more energy than 
>> the other.  These sets usually generate significant incidental FM 
>> along with AM on voice, and there is a lot a phase cancellation going 
>> on.  The BC-375 and 191s are notorious for this behavior.  If you 
>> look at the spectral and waterfall display of one of these 
>> transmitters in voice mode you will likely see that the majority of 
>> the modulation is on one sideband. We once had 4 such sets on in a 
>> net and some were generating mostly upper sideband modulation energy, 
>> and some were mostly lower sideband, all with full carriers of 
>> course.  You  need a balanced modulator to null out the carrier and 
>> select the desired sideband you want your SSB to be on.  With careful 
>> neutralization and finessing of the PA plate current dip you can get 
>> reasonable sideband energy balance in AM operation.
>>
>> Here’s a good link that describes the GF-11 in detail:
>>
>> https://www.radioblvd.com/RU16-GF11_Restoration.htm
>>
>>   Send us a pix of yours if you can!
>>
>> 73 de Chris AJ1G
>> Stonington CT
>>
>> Sent from my iPhone
>>
>>> On Jul 18, 2023, at 16:04, Captain D. <mkdorney at aol.com> wrote:
>>>
>>> 
>>> Open the Tube compartment cover, and near the back of the divider 
>>> between tube compartment and the rest of the radio you will see the 
>>> toggle switch that can turn on either upper sideband or lower sideband
>>> Mark D.
>>> WW2RDO
>>>
>>> In a message dated 7/18/2023 7:12:20 AM Eastern Standard Time, 
>>> aj1g at sbcglobal.net writes:
>>>
>>>     Well, now that you’ve got our attention, please tell us more!
>>>
>>>     Chris AJ1G
>>>     Stonington CT
>>>
>>>     Sent from my iPhone
>>>
>>>     > On Jul 17, 2023, at 18:26, MARK DORNEY via MRCA
>>>     <mrca at mailman.qth.net> wrote:
>>>     >
>>>     > I was surprised to find a small toggle switch in the GF-11
>>>     transmitter that allowed for operation on either low sideband or
>>>     high sideband.
>>>     >
>>>     > Mark D.
>>>     > WW2RDO
>>>     >
>>>     > “In matters of style, float with the current. In matters of
>>>     Principle, stand like a rock. “.  -  Thomas Jefferson
>>>     >
>>>     > Sent from my iPhone
>>>
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