On Thu, 25 Feb 2010, Bill M wrote:

I'm working on an NC-88 and a couple things aren't sitting right with me.

1. Overall 'oomph' seems to be missing. It receives well enough but even
benchside listening requires that the volume be up to about 75%. Doesn't seem
right. An AA5 would blow it away. Finger on the volume pot wiper gives a
very healthy hum so the problem must be further back.

2. BFO. Works but is really weak. I tried more coupling but no increase.
The Sensitivity control has to be almost at the floor to hear it. Its really
too weak to be functional.

I don't have a clue, but before SSB (and I can't remember whether this
receiver predates it, it likely doesn't matter for this purpose when it
came out), BFOs were relatively weak. Their purpose wasn't to provide a
good mixing action, just a beat note.

Which is why there were all those articles about turning down the RF gain
when receiving SSB on such receivers. I'm sure a lot had terribly weak
BFOs even then. And given that the same general design in general
coverage receivers carried over into the age of SSB, the age of the
receiver may not be that important.

There may be an issue, but perhaps your expectations are higher than the
design had in mind.

Michael VE2BVW

Recapped, many resistors found out of tolerance, voltage checks are all ok.
Some previous owner had the IFs badly mistuned. Found an intermittent
factory joint on the bandswitch.

I guess what I'm asking are these 'features' typical of the NC-88? I
wouldn't think so. Maybe the two symptoms are related?

Thanks for any comments.

-Bill WX4A