[TowerTalk] Slow Attenuation of Incoming Signal

[K8RI on TowerTalk]

----- Original Message ----- 
From: <K7LXC at aol.com>
To: <towertalk at contesting.com>; <n6kj.kelly at gmail.com>
Sent: Friday, October 20, 2006 12:08 AM
Subject: Re: [TowerTalk] Slow Attenuation of Incoming Signal


>
> In a message dated 10/19/2006 12:26:30 P.M. Pacific Daylight Time,
> towertalk-request at contesting.com writes:
>
>>  I've been noticing a strange phenomena that I'm hoping  someone can help
> explain.
>
>>  I'll be sitting in front of the  rig tuning the band and listening when
> all of a sudden the background noise  level starts to drop and signals
> start to drop in strength.  After a  couple of seconds signals are
> severely attenuated.  It's as if there  is a variable attenuator in my
> coax line and someone turned it from 0dB to  50dB.  A single tap on the
> CW key brings it right back to normal once  again.  It'll stay normal
> for minutes or even hours before doing it  again.  A single "dit" from
> the key always brings it back to  life.  I've never heard it do this on
> any band except 40m which leads  me to believe it is my 40m antenna,
> but I'm not sure about that.  I  run a common feedline all the way up
> the tower to a remote switchbox which  switches between my SteppIR and
> my 2 element 40m yagi.  If it's  limited to 40m then it's either in my
> rig OR between the switchbox and the  40m yagi.
>
>>  Anyone have an idea?
>
Are all of your antennas at DC ground? Is the 40 an ungrounded dipole?
If the answers to both of these are yes then the choke from the center 
connector on the chassis connection to ground may be open or disconnected.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com

>
>    Try the antenna plugged directly into your radio  and then see what
> happens. It's probably related to something else in your  signal chain.
>
> Cheers,
> Steve    K7LXC
> TOWER  TECH
>
>
>
>
>
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