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

["Ian White, G3SEK" <G3SEK@ifwtech.co.uk>]

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
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