[Milsurplus] Addendum 1: TCS Receiver Resurrection Tips.

[David Stinson]

"Losen?"  "Lossen?"   I should never write at midnight...

Iron core IF cans:  
The fixed caps inside the IF cans of the iron-core 
tuned IF cans are precision 75 pFd mica.
I've never found any bad and if so,
it's best to leave them undisturbed.
Be very careful if you decide to voltage test 
them for leakage.  
Accidently get that voltage across the IF 
coil winding and you will be very unhappy.

Those wires that feed through the rubber grommets
on the 1st and 2nd IF modules:  
It is very easy to get those caught between the 
module and the chassis when re-installing 
the modules.  Tuck them out of the way before 
reassembly.  I got caught with that one and 
nearly pinched the wire off.

TCS Crystals:
I've found that a large percentage of TCS transmit
and receive crystals are for 4435 KC.
Anyone have any insight into why this would be?

Speaking of crystals:
Here's a diagram of the Detector/BFO/Audio.
https://goo.gl/photos/6r4KVkauX3G2dtoW6
As an experiment, I inserted a 453 KC crystal 
at pin 4 of  the 12SQ7 and retuned the BFO
to put LSB signals in the right place.  
Putting the crystal earlier in the IF would mean 
the need to rework the DC grid bias of that stage 
and I didn't want to make that level llof changes to 
the original design.  Big, irreversable changes 
are forbidden in my radio world.

Of course, just poking a crystal in there introduced
a lot of loss, but it also sharpened things up a lot.
I could build the crystal and a little 
transistor amplifier in a "Borg Implant" powered
 by the filament buss and adjust the gain to make-up 
for the loss of the crystal insertion.
If I use a hi-Z input amp after the crystal, 
leaving it lightly loaded, the improvement 
should be dramatic.  Thoughts?

73 DE Dave AB5S