[AMPS] L4B
km1h@juno.com
km1h@juno.com
Fri, 16 Oct 1998 00:46:54 -0400
On Thu, 15 Oct 1998 21:58:25 +0100 "Ian White, G3SEK"
<G3SEK@ifwtech.demon.co.uk> writes:
>
SNIP
>
>"What price" comes into this very literally. In Europe the classic
>8.2V
>50W zeners are very hard to find.
Ian...in the Colonies:
Anywhere from $7 -15 depending on voltages and who has what when. K2AW
is often a very good source.
From the big catalogs, the choices
>are
>between a 20W diode at $10 (but probably under-rated in a flashover)
>or
>a 75W diode at $50 - and neither of those has adjustable voltage.
>
>The cost-effective alternatives then are either a string of forward-
>biased diodes or something involving a transistor.
Which is as likely to blow during an Oh-Oh ( aka: Oh Shit) as a zener. A
handful of 25 cent 1N5408's are less high-tech but also lots more
reliable to contesters and other hard users of amps. Personally, I
absolutely hate fixing things at 3AM.
>
>One reason for microwavers liking regulated bias voltage is that it
>allows more RF output in the common situation where drive power is
>hard
>to find and small tubes are being pushed to the limit. But mostly I
>think it's the "follow-my-leader" effect.
Pretty soon the 3CX100A5/7289 will be as extinct as 8873's the way the
23cm group abuse them.
73 Carl KM1H
>
>73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
> 'In Practice' columnist for RadCom (RSGB)
> http://www.ifwtech.demon.co.uk/g3sek
>
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>
>
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