George T. Daughters wrote:
>2: wouldn't a DC power supply like those used for
>computers be a good filament source? with a little
>tweaking and/or modification they could be set to
>the factory's recommended voltage, and they would
>act as a current source (at the limiting value for
>the supply) and as the filament heated up, they
>would change over to a regulated voltage. or is
>the noise output of such a (typically switching)
>supply just asking for another set of annoyances
>when in receive mode? (even if we have the "perfect"
>amplifier, we probably want to receive at least
>*some* of the time!)
A number of VHF mountain-toppers are using modified computer switch-mode
supplies for 6V heaters, to avoid problems with generator sags and
surges. Apparently the fully-enclosed and filtered units work well, but
I'm sure an open-frame or unfiltered switcher would be a disaster on
receive. Also, this is information relates to VHF - suppression of
switching transients may not be so good at HF.
Bottom line: it's worth a try.
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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