The AM Forum

I'm the ecstatic recipient of a collins 32S-1 and a 51S-1.
I see the 51S-1 can receive AM/SSB/CW and the 32S-1 is SSB/CW.
They are dusty but in nice condition and definitely keepers.

I assume the 51S-1 receiver is like the R390 in that it has about 30 'bands' created by the same number of crystals in the LO. Going to get the manual from the CCA.

Here is a more complicated question concerining the 32S-1:
Is it possible or simple to non-destructively add a low powered AM+sideband function to the mix such as many tabletop 'ssb' transmitters have?  AM being the afterthought on those types. This has two 6146s.

 - Or would this be inadvisable or just the wrong thing to do on this unit. Some good people consider these the grail or otherwise greatly desirable. I have to agree Collins is one of the very best, and people collect these things.. hole-drilling is certainly verboten.

Why not plate modulate it with an outboard modulator. This  could be done without any blasting. Like an Eico 720 and 730.

Johnathan N8QPC

Not a simple thing to do.

Ted, K1QAR actually has one with a mod that does this!
I think he might sell it.

The mod looks like an aftermarket thing, solid state, with several boards to get the job done.
We have not been able to track it down, or find any reference to it.

There may or may not be an article about it in one of the 1970s, early 80s mags.
I'm thinking maybe Ham Radio mag. Dunno.

                      _-_-

I'll have to read about those mods if I can find them, probably on the Goog. Not real sure I'd want to do anything too complicated.

Found the book on it. Call me nuts for thinking about it, but put it on CW and series-modulate the driver? Grab it by the plate & screen and hook to a small tube type regulated supply adapted for modulation. That supply may still be around here.

Probably over the years people have tried all kinds of things, better research all that before doing anything.

Again, CW is not CW.

They use a 700Hz audio oscillator!!
True.

Wacky?
Yes.

Could you unbalance the balanced modulator? I guess.
Memo sent to the Department of Absurdities?

Dunno.

I found this AM mod on the internet. It shoots a little BFO around the balanced modulator and 455KC sideband filter. This was apparently written up in the CCA newsletter, so...

Yes the frequency offset, but what else is expected on SSB transmitter. Among the many radios made, some indicate the 'true carrier frequency' of their carrierless channel, and some indicate something like the center frequency of the passband. It's disturbing that there is no standard.

I can see that a crystal could be added to provide the correct carrier frequency for AM. OK probably not strictly necessary.

Well enough of this.. Nice radios, could do AM. If that happens I'll write back when it's working on the air.  8-)

After consideration, can't do it on moral grounds. Looking at the unit and another that showed up, they are too clean and it would be wrong to go hacking into either of them.

I was thinking how many R390s and older more classic and heavy radios have suffered ill-considered and or undocumented mods and were never the same, and how I hated seeing that.

Just took some time to look at the big picture.

Good on ya, Patrick. :)

Fire 'em up stock and play radio.

If they don't please, pass them off to someone that likes how they grok the air.

73DG