[Boatanchors] TCS Transmitter: OK Smart People; Why?

[David Stinson]

I think I know why an outstanding transmitter like the TCS, with 
both MO and Xtal oscillators, never got real traction as a Novice 
rig (other than the high price at the time).

Those familiar with crystal-controlled transmitters of the 40s 
and 50s will recognized this pentode oscillator circuit:

http://home.netcom.com/~arc5/TCS/TCSXtal.jpg

The values in black are nominally the ones found in the many 
flavors of this circuit.  The values in red are those found in 
the TCS transmitter.  The TCS values bias harder and reduce the 
screen voltage considerably.  As a result, crystals like FT-243, 
CR-1, HC-6 and even large-blank FT-241 will not reliably function 
or fail to oscillate altogether.  However- I have a couple of 
pre-war, Collins-made large-blank transmit crystals:

http://home.netcom.com/~arc5/TCS/TCSTXXtalCollinsPreWar.jpg

With these installed, the oscillator is perky as a pug.  With 
parallel resistors installed to bring the cathode down to 500 
Ohms and the Screen dropper down to 22K,  all properly active 
crystals I've tried work well and give good drive.

The engineers knew what they were doing and what the result would 
be.  Why did Collins do this?  Were they trying to ensure only 
crystals bought from them would work?  Is this why it's easy to 
find TCS Receiver crystals, but Transmitter crystals are scarce? 
Curious. Thoughts?

GL OM ES 73 DE Dave AB5S