Date: Wed, 9 Mar 2016 05:44:04 -0800
From: jimlux <jimlux@earthlink.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] F12 C19XR Rivets
On 3/8/16 9:09 PM, Bert Almemo wrote:
> Jim,
>
> While I agree with most of you're writing I think you'll be hard pressed to
> get a solid 9 square inches of surface contact in your 1 inch tube with 3
> inches of overlap. Maybe if you put in a lot of SS screws or rivets at the
> joint. If you're using any kind of joint compound, like Penetrox, you need a
> certain pressure to make a good contact, as I'm sure you know. SS hose clamp
> + SS screws has been a good combination for me.
>
Don't forget the capacitance. 9 square inches separated by 1 mil is
about 2000 pF
at 14 MHz, that's an impedance of about 5 ohms. Even if there's a bigger
gap (say, 3 mils) the impedance goes up to 15 ohms, and in any case
capacitance is lossless: you just make the element a bit longer to
cancel the series C.
## I read zero pf across each ele joint...and zero dc ohms. That’s good
enough for me.
Jim VE7RF
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