[Milsurplus] BC-611 Transmitter Info Posted

[Robert Downs]

I will add to Breck’s excellent BC-611 transmitter write-up that the reason that Pogo-Stick antenna coils have lower inductance than the BC-611-(*) ones is that when both are fully extended, the Pogo-Stick antenna is several times longer than the BC-611 antenna, and hence requires less inductance in series with it to bring it to resonance.  

 

I have many of all of the BC-611 antenna and tank coils, including the Free World’s supply of the antenna coil that covers 3885 KC, so have never had any impetus to find out but as the Pogo-Stick goes down to a lower frequency than does the BC-611, there may be a Pogo-Stick antenna coil that will tune a BC-611 antenna to 3885 KC.  But I don’t know that for a fact.

 

On the general subject of the BC-611 antenna and tank coils,  they will be found marked two different ways.  The early ones are all marked with a single frequency and with Galvin part numbers.  The later ones are marked with a frequency range and with the Signal Corps model number.  But both groups are the same, meaning that as an example, the range-marked coils that cover 3885 KC are marked C-360 (3825-4025 KC) for the antenna coil and C-371 (3825-4225 KC) for the tank coil.  (and note that in this case C = Coil, not Capacitor).  An antenna coil marked 3885 KC is the same coil as a C-360 and a tank coil marked 3885 KC is the same coil as a C-371.

 

One coil related problem that I have encountered twice was where the C-371 tank coil worked OK but in order to get the antenna to tune up on 3885 KC, I had to substitute a C-361 antenna coil.  Both radios had a very heavy or thick coating of MFP varnish to the extent that the top end of the chassis was brown instead of amber.

 

As before, if Breck wants to add any of the above to his write-up, feel free.

 

Robert Downs

 

From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of B. Smith
Sent: Friday, July 17, 2020 17:49
To: Military Radio Collectors Association; Milsurplus
Subject: [Milsurplus] BC-611 Transmitter Info Posted

 

I've posted "Bench" notes on the BC-611 transmitter. Tabs include info on Bench Power Connections, Antenna Coil Modifications, Final Amplifier Tuning, A Test Case  for Alignment, Output power testing, Pogo Stick Coil Info, Microphone Replacement with substitute elements, Battery/Inverter info, and of course a Miscellaneous Section. 
73 breck k4che/3

http://k4che.com/BC-611%20Bench/BC-611%20Transmitter/BC-611%20Transmitter%20Bench%20Tips.htm 

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