[MRCA] GF 11 transmitter

[Michael Hanz]

Yup.  Nothing to do with upper or lower sidebands. Here is the 
explanation in the manual:



On 7/18/2023 7:39 PM, B. Smith wrote:
> 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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>>
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>
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-- 
Michael Hanz - KC4TOS
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