[ICOM] IC-706MKIIG And Ambient Noise

[George, W5YR]

This situation reminds us that noise and signal are both electromagnetic
waves that differ only in some of their properties. In the main, we tend to
object to "noise" and to dislike it. However, a receiver that won't respond
to noise is unlikely to respond very well to "signal." And we would dislike
that even more . . .

Removing the antenna connection is the test: if the noise goes away, it is
not being conducted into the radio through the power wiring, etc. but rather
is being picked up through radiation by the antenna.

This test tells us another useful thing or two: if connecting the antenna
increases the level of noise out of the speaker, then the receiver has
adequate gain above its noise floor. In fact, one can insert front end
attenuation until connecting the antenna no longer increases output noise
and the IP3 has been increased approximately by the amount of attenuation
thereby inserted.

On my PRO2 I can insert 18 dB attenuation even on 10 meters and still have
an increase in output noise when the antenna is connected. This feature
increases the IP3 of the PRO2 by 18 "dB from Heaven." See Adam's (VA7OJ)
website for a better description . . .

73, George W5YR
Fairview, TX
w5yr at att.net
http://www.w5yr.com


----- Original Message ----- 
From: "Davies, Doug A FOR:EX" <Doug.Davies at gems3.gov.bc.ca>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Wednesday, June 16, 2004 4:15 PM
Subject: RE: [ICOM] IC-706MKIIG And Ambient Noise


>
> Did you try the noise level with the antenna disconnected?
>
> Jerry
> WC8R/3
>
>
>
> Thanks for the reply.  With the antenna disconnected, I have absoultely no
> noise.
>
> Doug  VA7DD
>
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