[Radio Wrangler]

That was originally designed as a selective wavemeter, more of a general lab instrument (3586A) than a telecomms unit, in Loveland CO. We added all the FDM bandplans and changed a fair bit of hardware to suit the SLMS (as the 3746A) role and it worked well.

It was the only SLMS with a crystal filter. 50.015625MHz two stages of lattice section in the first IF. The crystal manufacturer Loveland had found that could make crystals which stayed linear to quite high levels still had difficulty making them. The second IF is at 15.625kHz and all the filters are pot core based. The 3746 has a further conversion and a 22Hz active filter for measuring pilot tones.

I did a variant of the 3746A with a frequency extender box to cover to 90MHz. Note that on telecomms boxes, suffix 'B' was not a later version. An A suffix meant to CCITT standards, a B suffix meant Bell.

No, I won't weep. I saw the bulldozers go in and flatten the place where so much was designed and made.

Anyway, the SLMSs are very serious kit in terms of large signal handling. With switched IF gain in large chunks, they don't make good HF receivers (I tried, of course!) The OCXO may well be the most valuable thing there. The synth phase noise is quite decent but it covers 50.015625 to 85-ish MHz. Not quite an octave, so that spoils any idea of dividing down as a low noise sig gen.

But, in the front-end circuitry, there's a fair bit to be learned about high dynamic range design, and that can be applied to substantially less esoteric problems.

The NPR box was 3724A + 3725A + 3726A It was split into units which could be carried.

I had access to all the gear needed to thoroughly measure RX performance, and I managed to borrow and test all sorts of receivers. This meant I could test them in a uniform way. Manufacturer's data sheets always spec'd things slightly differently in ways which couldn't be directly compared. Different reviewers had their own pet conditions. So with that background, I know the JRC receivers and how they compared to the state of the art at the time. The Japanese firms tended to put slightly better receivers in their transceivers than they put in pure receivers. They saw the shortwave listener market as less demanding than the transceiver market. JRC seemed to do the receiver first, and then develop a transceiver from it.

Anyway, it's the active antenna that's the limiting factor for the OP.

David