Very true! Forgot about the capacitance.
Bert VE3NR
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
jimlux
Sent: Wednesday, March 09, 2016 8:44 AM
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.
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