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Old March 8th 06, 07:29 PM posted to rec.radio.shortwave
Telamon
 
Posts: n/a
Default Why antennas aren't necessary for shortwave listening.

In article . com,
"N9NEO" wrote:

A couple of years ago I bought a Racal RA17 receiver. I used it for
a few months and now it patiently waits for me to go thru it more
completely. I think it has a noisy circuit in it now.

I recall listening in on some 75m guys when I realized I hadn't
connected up the antenna. Granted many in the 75m crowd are probably
running CB type power levels, but on the other hand my shack is down
in the basement. I tuned around the bands and was surprised what the
radio would do sans antenna.

I'm not sure what kind of a front end the Racal has in it but it
certainly is a sensitive beast. I hope to one day get it out of the
inbasket and back into the shack. I would like to put it next to
another SP600. I had to sell my SP600 in order to get the Drake R8B.
The R8B is of course my favorite.

So there ya go. Now if somebody knows what the Racal has for front
end please tell.


This indicates a problem with the radio. My best guess is that the
signals are coming in the power mains and coupling to the antenna
input. You will not be able to control what you hear with the antenna
connected to the radio.

You could try some power line filtering to see if the signals go away
with no antenna connected. If you don't solve this then obviously you
will be hearing a lot of power line noise on the radio.

Another thing to try would be a 50 ohm resistor with short or shielded
leads. With the resistor across the antenna input the radio should be
quiet.

--
Telamon
Ventura, California