[Milsurplus] RT-311/ARC-38 Question

[Mike]

I need some info from AN/ARC-38 experts out there, especially those
familiar with the AM RT-311/ARC-38 (as opposed to the SSB
RT-594/ARC-38A).

I recently acquired a complete, early 1960s overhauled, excellent
condition RT-311.  The stabilized master oscillator (SMO) assembly bears
a label "Equipment modified for SSB" even though this set is still in
the AM configuration.  It has not been converted to an RT-594 set, and
the SMO in this RT-311 is very very different from the SMO in the RT-594
SSB unit.

The SMO in my RT-311 has the cable removed from Z2201 to P2112 on the
SMO slug rack assembly.  It also has no connection made to J2110 on the
SMO master oscillator subassembly, which normally connects to frequency
correcting capacitor C2199.  The wire from C2199 does disappear into
some harness not visible without disasssembly of the SMO unit.

The SMO for the SSB RT-594, by the way, has all this wiring still in
place as originally built.

The SMO unit is marked also with "MOD 1" on it.

I've looked through my AN/ARC-38 manual NAVAIR 16-30ARC38-502 as revised
15 OCT 71 and find no mention of SMO modifications of this sort.

I'm wondering what the purpose of this SMO mod was, and why an AM SMO
would be marked as being modified for SSB, yet whatever mods were made
did not correspond to the mods made on the SSB RT-594's SMO.

Thanks,
Mike / KK5F