[Amps] Ferrite-loaded plate choke

[DF3KV]

----- Original Message -----
From: "Angel Vilaseca" <avilaseca at bluewin.ch>
To: <amps at contesting.com>
Sent: Saturday, January 08, 2005 12:15 PM
Subject: [Amps] Ferrite-loaded plate choke



>I am currently building my first HF amp using a couple of 4cx 250b.

>I have found in the literature that the plate choke is quite a
critical
>component and I found a few kinds of plate chokes designs.
>Recently I found this text (see below) on the Internet.

>Now I saw that the use of ferrite cores is classical in filament
chokes,
>but I never saw a ferrite core recommended in a plate choke.

>What do the experts on the list think about using a ferrite core in a
>plate choke?

Hi Angel.

Rohde&Schwarz did that in their amplifiers.
For instance in their model SK-1, which I own, they use two chockes of
75 and 90µH respectively while the latter is switchable between 90 and
30µH.
Both are series connected, on the lower frequencies the total is used,
on the higher 30µH are switched off.
The amp is autotune from 1,5-30MHz.
The 90µH choke measure 30µH when the ferritroad, 40mm diameter 90mm
long,  is taken out

73
Peter