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Topband: Reactance problem

To: <topband@contesting.com>
Subject: Topband: Reactance problem
From: n4zr@contesting.com (Pete Smith)
Date: Wed, 13 Mar 2002 08:12:44 -0500
At 06:21 AM 3/13/02 EST, W2pm@aol.com wrote:
>I don't suggest this is the issue here but I have found after extensive
work with it that the MFJ259B is quite sensitive to BC band and/or any
other "strong RF" coming in off the antenna in question. I do not live
particularly close to BC stations but was getting strange and inexplicable
readings on my Inv L and other topband antennas. Then I bought the tunable
filter device they sell and all readings fell into expected or likely
boundaries. 

I was really surprised when a measly 500 watt AM station 5 miles away on
1550 kHz drove the MFJ nuts on my 160 meter shunt feed.  The station was 50
over 9 on my Mark 5.  Moral is it doesn't take *that* much.  In my case, it
was evident that something was haywire because the readings were all over
the place and varied widely over a short timespan (perhaps a function of
modulation).

Would it be feasible, where you believe that it's only one AM station, to
build up a little series trap?  Could the notch be deep enough, or does it
take more elaborate circuitry like MFJ's add-on?


73, Pete N4ZR

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