[Amps] Fl2000b grid choke

[R.Measures]

On May 19, 2004, at 5:13 PM, Paul Erickson wrote:

> I am fixing an FL2000b amp for a friend, and among other things the=20
> grid choke is black from over heating. I am having trouble finding one=20=

> locally. It is one of the old receiving type millen/miller single=20
> layer chokes. Anyone know where I can find a good replacement?

=F0  Paul -- Replacing the choke is not the fix.  The choke was toasted=20=

because of a burst of grid-I.  The fix is to improve the VHF stability=20=

of the amplifier so as to lessen the chance of burst in grid-I.  Since=20=

a Cu-wire choke is a poor fuse, and a burst in grid-I can damage a=20
572B, it would be better to limit grid-I with a fusing resistor of 30 -=20=

39-ohms @ 0.25w.  -- notes --  The resistor type:  Carbon-film is=20
better then MOF for this application.  // To protect the grid fusing=20
resistor from 10m RF from the adjacent anode, the grid should be=20
bypassed with c. 1500pF.

=BD=C5
> --=20
> ----------------------------------------------------------------
> cheers, Paul - VA7NT - email: va7nt at telus.net
>
> "Those who hear not the music, think the dancers mad."
>
>
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>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org