Hi Chris,
at the risk to state the obvious:
A LPF of a solid state PA has 50 Ohms in- and output impedance.
A tube type PA needs a LPF which transforms from several kOhms on the tube side
to 50 Ohms at the output.
Therefore the values for the lumped reactances differ considerably from the
non-transforming LPF.
Moreover design parameters like optimum loaded Q for the needed flyweel effect
etc. come into play.
The ARRL Handbook,also old versions, cover this subject in depth.
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Chris Wilson
>Sent: Thursday, August 03, 2017 4:19 PM
>To: [email protected]; [email protected]
>Subject: LF: LPF for a valve based (tube based) LF amp?
>
>Hello LF'ers,
>
>
>My next contemplated project is a GS35B valve based LF amp. I have the
>HT supply, a couple of GS35B's to play with and a suitable filament
>supply. My question is can I build an air wound LPF based on exactly
>the same values as the one I use on my W1VD FET based Class D amp?
>That gets pretty warm and I use a small PC processor fan on the centre
>toroid, but I am unsure if the filter characteristics are specific to
>a FET based amp in some ways?
>
>W1VD amp schematic here: http://www.w1vd.com/137-500-KWTX.html (1
>kW amplifier) http://www.w1vd.com/137-500-KWRev3.0.pdf
>
>
>
>W1VD LPF details here: http://www.w1vd.com/LPF.html
>
>http://www.w1vd.com/LPF.pdf
>
>
>
>--
>Best regards,
> Chris mailto:[email protected]
>
>
>
>---
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