[Boatanchors] Collins R-627/URC-8 receiver

[Nick England]

Thanks to a very kind friend, I have acquired a Collins R-627/URC-8
receiver - The URC-8 was a prototype designed to replace the Navy's
venerable TCS sets. I have been tracing out the circuitry because
there are wires hanging out the back, some mods, and I have no manual
and barely any other info. Collins part number is 522-9273-004.
http://www.navy-radio.com/xmtrs/urc8.htm

It is an interesting design (opposite to the usual 51J-, 75A- scheme)
with a PTO as the HF osc and a crystal-controlled LO for the 2nd
mixer. I am wondering if Collins made any other receivers with this
scheme....
Dual conversion, general coverage 2-30 mc in 4 bands.
One piece of info says 455kc 2nd IF and there are two mechanical
filter sockets in the IF/BFO/AF module
There is a 70H-10 PTO (2.58-4.58 mc) as the HF oscillator.
I had been trying to figure out the conversion scheme and beyond
figuring the PTO was multiplied as follows, had been scratching my
head as I saw only one crystal socket that could act as the fixed LO
for the 2nd converter.
Band (mc)   multiplier          PTO x multiplier (mc)
2-4                 x1                    2.58-4.58
4-8                 x2                    5.16-9.16
8-16                x4                   10.32-18.32
16-32              x8                    20.64-36.64

Then eureka, I finally found 4 xtals buried deep within the RF deck -
this is a really compact bugger, but with flashlight and magnifier I
managed to read the freqs. Here is my guess at the conversion scheme -
using mid-band for illustrative purposes.
(freq in kc)
RF input     PTO x mult     1st-IF        XTAL     2nd-IF
 3000            3580               580        1035       455
 6000            7160             1160        1615       455
12000           14320            2320        2775      455
24000           28640            4640        5095      455

Yep, I found a couple of IF transformers with 4 coils/housing so it
probably really does have a different 1st IF for each band.

So I am wondering if Collins (or anyone else) made any other receivers
with a scheme like this?? Anyone? Anyone?

cheers,
Nick K4NYW
www.navy-radio.com