[R-390] A vs non A

[William A Kulze]

I feel like I need to clarify my thoughts on sweeping. As I mentioned, it did make a difference on the old hammarlund, but I haven't seen a need for it on the R-390a. Mainly, on the R-390a, I have found hooking up the IF out to an SDR to be a great tool, also. You can see the shape of the bandpass. I haven't found a problem with the filters not being flat. But I have noticed that my 8kc filter isn't centered on 455kc, it's a little above that. It's more of a curious thing than a problem. I have tuned mine staggered and all peaked at 455, but not since doing it this way, where I can see it. Maybe I'll check it out sometime, see if there's a difference.

I'm sure that even though a meticulous alignment would get the radio closer to what the engineers had in mind, it wasn't needed for the beast to perform it's day to day duties, and guys in the field did what they could with what they had, and it sufficed. 

I went to keesler for ground radio, learned Rx principles on R-390 schematics with colored pencils and everything, but I got sent to hickham to work in the airways/scope station and never saw another one (except the one they used for recording WWVH on the big 10 channel tape recorders) until I got my own R-390a quite a few years later.

I am most grateful for everybody out there that shares their experience and knowledge on these radios. They are most certainly a thing of technological beauty.

Bill W2NVD


-----Original Message-----
On Behalf Of Roger Ruszkowski

Subject: Re: [R-390] A vs non A


Fellows,

Sweeping did come along about 1971.

It is not in the manuals.

At best there was a study guide not even a real TM publication on how to set up the test equipment and do an alignment.

We also had a frequency counter to adjust the end points on the VFO and to set the BFO, we also used that to set the AN/URM 25 output frequency. The counter is not in the TM either.

The sweep generator and frequency counters helped.

More toys is always good. Not required but desired.

As some of the Fellows describe, A sweep and a scope make alignment so much slicker. 

If you gotem useem.

If not, worry not.

Roger.