[Milsurplus] TCS: T-17 and RS-38 Microphone Mystery

[antqradio at sbcglobal.net]

What is the turns ratio of T-101 versus what is used in the other modulators?



      From: David Stinson <arc5 at ix.netcom.com>
 To: mrca at mailman.qth.net; milsurplus at mailman.qth.net 
 Sent: Monday, December 21, 2015 10:21 AM
 Subject: [Milsurplus] TCS: T-17 and RS-38 Microphone Mystery
   
Been refurbishing at TCS-13 (photo on my QRZ.com page).
I dug-out all my T-17s and RS-38s, looking to 
"seperate the sheep from the goats."  Most of these don't 
work with either SCR-274N or SCR-287.

To my great surprise, ALL of them work on the TCS
transmitter, the worst of the lot still doing at least 70%
modulation.  The 274N and 287 use current-limited 
filament voltage to power the carbon mike.
The TCS uses the cathode bias of the modulators.
Diagram attached.
So- why do they work with the TCS, but not with
other rigs?

73 DE Dave AB5S

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