[TowerTalk] F12 C19XR Rivets

[Jim Thomson]

Date: Wed, 9 Mar 2016 05:44:04 -0800
From: jimlux <jimlux at earthlink.net>
To: towertalk at 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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