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[TowerTalk] Measurring at the antenna feedpoint

To: <>
Subject: [TowerTalk] Measurring at the antenna feedpoint
From: (Tom Rauch)
Date: Tue, 09 Jun 1998 21:31:38 +0000
To: <>
> Date:          Mon, 08 Jun 1998 23:53:22 -0400
> From:          Dick Green <>

> It's awfully hard to find the resonant point if you can't touch the darned
> thing. The MFJ was somewhat better, but still difficult to pin down the
> resonant point any sharper than within 50 KHz or so.

You can touch and let go. I do that with my 259B on ten meter and 
higher when checking long balanced lines. I set it on an insulated 
support (like a cardboard  box) and keep me mitts off the metal 

That works  well except above maybe 100 MHz, where the case becomes a 
pretty good ground all by itself.

With verticals employing good ground systems, unbalance is very good. 
There should be absolutely no need to keep the case ground isolated.  
If the Autek is messing up on a grounded vertical system, some else 
is happening.

> I've had more luck with readings that make sense on the tribander and 80M
> vee. I thought it might be B/C interference, but this is a rural area with
> no AM stations within 10 miles, and none of them strong.

Any potential difference between the terminals can mess these gizmo's 
up. The detector diodes pretty much directly connect to anything 
causing a small differential voltage across the RF connector. 

I've seen low frequency AC from ground loops goof em up.

73, Tom W8JI

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