[AMRadio] Receivers

Todd, KA1KAQ ka1kaq at gmail.com
Mon Jul 31 10:30:37 EDT 2006

Hiya Rick -

I'll weigh in with my 2¢ worth since I've been away and missed all the fun.

The 75A-4 was designed primarily for SSB operation and is therefore
tailored more to that kind of listening: product detector, mechnical
filters, etc. It is indeed 'ham bands only' with some additional
coverage around the edges. In my view though, and contrary to those
who have said it has 'poor audio', I'd say instead that it has
less-than-ideal AM audio. The biggest reason for the audio issue is
the 6 kcs mechincal filter for AM. Not bad, but not the best either.
There are other options including 8 or 9 kcs that plug in and help out
a lot. But ask yourself this: how often can you open up the receiver
for full fidelity these nights? I'm not crazy about mechnical filters
for casual listening, but combined with the passband tuning in the
75A-4, you have a receiver that can switch quickly to 'battle mode'
when conditions deteriorate (as they do regularly on 75).

The SP-600 is a good band cruiser with its nice flywheel tuning, but
also lacks a bit in the audio arena. Not bad, not the best. They get a
bad rap for drifting, but this is almost always cured by moving the
tap on the transformer up a notch to 125v. I have mine in the rack
with the R-390 and R-390A.

Again, my opinion only, the R-390 is the better listening receiver
than the later A since it doesn't use the mechnical filters. The A is
the cost-reduced (and more plentiful) version, but did add the filters
which come in handy for bad band conditions. Biggest difference
between the A and the 75A-4 is the R-390A can be opened up to 16 kcs,
but will still ring on stronger signals. Of course, tuning any R-390*
is a lesson in patience and wrist stamina.

R-388/51J-3 is as stable and accurate as the 75A-4, but also suffers a
bit in the audio output. R-388A/51J-4 is even worse when it comes to
audio. Both are general coverage of course, AM/CW, no product
detector. I had a '388 until a few months ago, traded it off. Wouldn't
mind finding another someday, but in no hurry really.

So as others have said, it really depends on what kind of listening
you want to do. Keep in mind that many receivers like the R-388,
SP-600 were made primarily for communications work and not intended
for high fidelity audio. Same thing goes for the 75A-4. This doesn't
mean they have awful audio, just not as good as something with
push-pull 6V6s. If it's full audio you want, get any of the Super Pros
prior to the SP-600 (SP-400 and older), SX-28*, NC-240D, NC-183 etc.
You can run off the diode load of the R-390A, but that involves an
external amp and more mess.

Don is right of course: there are some receivers you just need to
have. I like Bill's advice, also: buy one of each, keep what you like!
Best bang for the buck? R-390A, hands down. You get the most radio for
the least amount of money. They are plentiful, and cheap (if you don't
shop exclusively on epay). The modular design makes it 'easier' to
service, but a Sky Buddy it's not.

~ Todd,  KA1KAQ

On 7/29/06, Rick Brashear <rickbras at airmail.net> wrote:
> Thanks Don...
> Do you mean it is a better SSB than AM receiver?
> Rick

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