----- Original Message -----
From: <K7LXC@aol.com>
To: <towertalk@contesting.com>; <n6kj.kelly@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@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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