Why antennas aren't necessary for shortwave listening.
 

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.

73
Bob
N9NEO

Why antennas aren't necessary for shortwave listening.
 

On 8 Mar 2006 10:03:33 -0800, "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.

73
Bob
N9NEO

The Racal is an excellent receiver.

Probably just has a bad thermionic device.

The receiver is deceptively quiet but it is indeed sensitive. Works
well on SSB with the BFO, if you back off the IF gain a tad.

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

Why antennas aren't necessary for shortwave listening.
 

On 8 Mar 2006 10:03:33 -0800, "N9NEO" wrote:


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.

73
Bob
N9NEO

I recently picked up a used Sony 2010 and was astounded that it would
pick up the nightly 3922 net with just the built-in 47" whip antenna,
even the 100 watt guys 500 miles out.

bob
k5qwg

Why antennas aren't necessary for shortwave listening.
 

On 8 Mar 2006 10:03:33 -0800, "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.

73
Bob
N9NEO

There's a lot of LC filtering in the front-end. I'm sure that's
probably grabbing some energy.

Why antennas aren't necessary for shortwave listening.
 

Bingo. I think I recall some High Q tunable LC circuits in the front
end. And yes, perhaps some of the energy coming in the power leads,
but I wouldn't be so quick to call that a problem. Call it a design
feature :) Anyway, yes, a nice receiver.