"AI4QJ" wrote in
:


"Roy Lewallen" wrote in message
...
AI4QJ wrote:

As another poster said, there is very high noise at this frequency.
The way this radio works is to use the coil as both an antenna and
the resonating inductance in the tuned circuit. I have found that,
in high noise applications like this, often the best way to get a
clear signal is to off-tune the receiving antenna, for example,
tuning the receiving circuit to the frequency you need but using a
shorter antenna. A 40m antenna often works well for receiving 80m
and 160m stations without all the noise. . .

Do you mean you can get a better signal/noise ratio with a 40 m
antenna on 80 or 160 than with a half wave 80 or 160 meter antenna?

....
When other people complianed of noise, it was a common practice for
them to use 2 transceivers or a transmitter with a separate receiver
on 75 80m. The transmitter of course was tuned as close to 1:1 as
possible but the receiver was tuned to a higher VSWR to 'tune-out' the
noise, yet the signals higher than noise came through very well....

I note you are distancing yourself somewhat from this explanation, but
apparently supporting it. A foot in both camps.

Is the assertion supported by any sound technical explanation.

Roy gave one possible explanation of why reducing receiver input may
improve S/N ratio, but you later dismiss that (RX IMD noise) as a likely
explanation.

Fundamentally, wouldn't you expect S/N to degrade in a linear receiver
system as you decrease the Signal+Off-Air-Noise wrt the receiver
equivalent internal noise?

Have you actually measured and documented the claimed improvement, or can
you cite a reliable experiment? Can you really dismiss RX IMD noise as a
significant contribution? Do you have another likely explanation?

This was/is something other people do routinely and is somewhat better
than an old wivws tale. Of course, by not tuning in the noise, you

So, if it cannot be measured, if it cannot be explained, isn't it no more
than an old wives tale?

Owen