On Sat, 9 May 1998 00:31:47 +0100 "Ian White, G3SEK"
<G3SEK@ifwtech.demon.co.uk> writes:
Lots of SNIPs
>increases faster as the frequency is reduced into the HF region.
Ian, I have a problem understanding your last statement. If the L was
properly selected for a particular tube AND circuit why would the Q
always detrimentally increase at a lower frequency? I look at the
suppressor network as a series trap and would expect the response to be
somewhat uniform on either side of its optimum frequency. The ideal
suppressor would then be only frequency dependent over the "parasitic"
range of the particular amp.
I know of no modern tube that requires any excessive R dissapation at
30MHz. Indeed, the parasitic frequencies are well above 50MHz and if the
suppressor was designed for the parasitic it should then run cold at
28MHz.
One very good argument for a lossy L is that it works equally well...or
poor over a much wider frequency delta. The "classic" suppressor may very
well be far superior at some particular narrow range of frequencies...but
what is its characteristics outside of that area?
The issue, as I see it, is a "monkey see, monkey do" attitude. Someone
published a suppressor design back in ancient days and it has been copied
ever since as a cure all for one particular tube in one particular layout
. Ian, you have a similar problem trying to educate people about tetrode
screen supply design.
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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