[Milsurplus] AN/URT-18, URC-32, KWT-6 transmitter - Part Needed

[Jim Whartenby]

Todd
The closest I can find to your spec is from McMaster-Carr:

1679K24, Urethane / Kevlar core
6484K122, Neoprene / Fiberglass core
either is less then $3.00 
60 teeth, 12 inch outer circle, .2 inch pitch, 1/4 inch belt width so the belts 
will have to be split in two.

The problem with the SMO is the synchronicity between the PTO and the 
Interpolation Oscillator.  The I/O has most likely drifted high so one needs to 
add some capacitance to the tank circuit.  All it takes is a few pF (mmf) of NPO 
silver mica caps but the pain is all of those 0-80 (or are they 1-72?) screws to 
get the cover off the I/O.  Once the I/O frequencies are within spec, set the 
PTO and I/O to the proper frequencies and insert the I/O back into the SMO.  I 
have done 4 SMOs now and this was what was out of kilter on all of them.  I had 
no problems with the PTO properly tracking at all; 2 to 4 mcs locking up every 
500 cycles.  Once the I/O was back on frequency, all was as it should be with 
the radios on receive.

Besides re-capping the power supplies (don't forget the electrolytic in the PA), 
replace the bearings in the blower motor.  You won't believe the difference!
Jim



----- Original Message ----
From: "Todd, KA1KAQ" <ka1kaq at gmail.com>
To: milsurplus <milsurplus at mailman.qth.net>
Sent: Mon, November 15, 2010 12:20:00 PM
Subject: [Milsurplus] AN/URT-18, URC-32, KWT-6 transmitter - Part Needed

While we're on the subject of the KWT-6/URC-32 family, does anyone out
there have a source of timing belt for the 786E-1 Frequency Generator?
Mine is dried out and has the nylon cord showing in places where the
rubber has fallen off.

Info from the manual describes it as having: pitch .187 in., pitch
circumference 11.781 in., width .125 in., number of teeth 63

Collins p/n 233-0082-00

I've had zero luck tracking one down in the last 10+ years beyond
hearing from a fellow in TX who had parts for sale and said he had a
cross reference number for current production belts, then disappeared.

Once the belt is replaced I can get to working on the stabilized
master oscillator to get it to sync up again. Right now I'm afraid to
touch it for fear of the belt breaking and losing the timing. Looks
like a PITA to re-time.

Would also like to find the .01 kc converter module p/n 528-0397-00 as
well. Mine has the dummy plug in place.

TNX for any leads or info -

~ Todd,  KA1KAQ/4
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