Frank Dresser wrote:
"Cowboy67" wrote:
Howdy all,
My brother-in-law just gave me a Hallicrafter S-20R receiver. I am
trying
to gather some info regarding it. My question to you is...If this is a
receiver, then why the toggle switch for send and receive?
The switch is would be used if the radio was used as a ham receiver. The
operator would switch the radio to "send" to silence the receiver. It's a
confusing label, and the later radios used "standby" rather than "send".
What does this
do?
By modern standards, the S-20R is a poor ham radio, so the switch is almost
useless. Actually, it's worse than useless, because flipping the switch
puts a strain on the 80 rectifier tube. I had a marginal rectifier tube in
my Hallicrafters S-40A, and I'd see sparks inside the tube when I flipped
the switch back to "receive". I guess that was OK back in the days when
rectifier tubes could be bought with pocket change. Now you should just
leave it on receive all the time.
By the way, the S-20R is still a good radio for shortwave listening. But
the original paper capacitors and probably the electrolytic capacitors are
bad. The paper capacitors are little more than a roll of foil and paper,
and the paper holds up about as well as any other cheap paper from around
1940 would. When these capacitors fail completely, they can also ruin tubes
and hard to find transformers. Modern plastic film capacitors are cheap and
last indefinately.
Thanks in advance!
You're welcome!
I have a soft spot for the S-20R because it was my first 'real'
shortwave receiver more than 30-years ago. I bought it for $15 when I
was in college. I replaced all the paper caps' and did a complete
alignment. Over the years the radio became a test bed for trying
different kinds of circuits. I learned a lot about shortwave receiver
design from that radio. I also built a digital frequency display for it.
The parts cost about $100 in the mid' 70's! Today you can buy a
shortwave portable with a display and much better performance for that
amount. I wouldn't recommend using the S-20R as your primary receiver
but you can still have fun with it for casual listening.
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