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Re: Topband: Shunt feeding the Skyneedle - new developments

To: "Carl Braun" <Carl.Braun@lairdtech.com>, "'160'" <topband@contesting.com>
Subject: Re: Topband: Shunt feeding the Skyneedle - new developments
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Fri, 21 Feb 2014 20:02:09 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Since then I've moved the variable capacitor inside the panel and mounted it to a ¾" think Plexiglas sheet mounted to the back plane with nylon bolts and washers. There is a 1" air gap between the Plexiglas and the backplane. I now have seen the 42+j0 ohms change to 45 - j11 ohms...that's the lowest reactance I can tune the capacitor for. Not really sure if its +j11 ohms or - j11 ohms but I assume if the reading was + j11 I could continue to tune it out with the capacitor but I cant.

Does the capacitor not play well with a steel enclosure?>>>>

Any enclosure will change things, especially a metallic enclosure. Just readjust the cap.

<<<<The other strange situation I'm experiencing is when I connect my Array Solutions static bleed choke to the feed thru insulator at the outside of the panel to ground the resonant frequency jumps to 2.014 MHz at 25 +j0 ohms...remove it entirely and I'm back to my 45 - j11 ohms.>>>

The choke is completely unnecessary with a shunt feed tower. It won't help a thing, so leave it out.

73 Tom
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