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Re: [Amps] roller L standard value per meter band

To: amps@contesting.com
Subject: Re: [Amps] roller L standard value per meter band
From: "Ian White, G3SEK" <G3SEK@ifwtech.co.uk>
Reply-to: "Ian White, G3SEK" <g3sek@ifwtech.co.uk>
Date: Sun, 23 Nov 2003 08:38:53 +0000
List-post: <mailto:amps@contesting.com>
skipp isaham wrote:
Hello gang,
-
The 4cx1000 project that some of you helped
locate the original text for...  mentions the roller
L value is set about .16uh per meter of
operation.
40 meters would be about 6.4uh of roller
inductance.
Is this a generic roller value for this size of
operation? an approximation by the author?
...or a x-amount of L/meter value from some
chart or table?
I'm curious where this .16uh/meter value
came from.

Start from the optimum load impedance for that particular tube.


Plug that value and a working Q into the design formulae for a Pi-network.

The results are reactance values (in ohms) for L, C1 and C2. These values are independent of frequency.

For a given reactance, the actual values in pF and uH must increase as the frequency goes down... so the trick is to convert them into pF and uH "per metre of wavelength."

But also remember that some of our band names like "20m" and "40m" are actually several percent different from the true wavelengths.


-- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book' http://www.ifwtech.co.uk/g3sek _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps

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