Why?
No room for 3-500Z's or 4-400's?
Carl
KM1H
----- Original Message -----
From: "Bill Smith" <ko4nrbs@yahoo.com>
To: <amps@contesting.com>
Sent: Tuesday, April 12, 2011 8:47 PM
Subject: [Amps] GU-84B Conversion
> I'm considering converting my old Swan Mark 1 (two 3-400Z tubes) to use
> one GU-84B. Some time ago I replaced the panel bandswitch in the Swan
> with a Radio Switch Model 86 six position switch with two wafers. At that
> time I also replaced the tank coil with one that was made for the National
> NCL-2000 amplifier. My new bandswitch required me to rearrange the RF
> compartment considerably.
>
> The transformer was replaced with a new one from Heyborer in Michigan. At
> that time I had them use the next larger diameter wire in the HV and
> filament windings when they wound it. The caps, etc. were all replaced
> with snap in type on a circuit board.
>
> Ok that's the history of the amp to date. It has a resting plate voltage
> of 2900vdc and 2500vdc or so under load.
>
> Readings with two 3-400Z tubes:
> Plate Current Readings on Operate HV Setting (SSB):
> 270ma using a Tuning Pulser
> Resting Plate Current is 190ma
> 460ma SSB Peak (Talking in Mic)
>
> Plate Current readings using CW Mode(1500vdc)
> Key down 660ma
> Resting 80ma
> SSB 320ma Peak
>
> My question is will the GU-84B perform satisfactorily with this
> transformer? I know I'll need another filament transformer and one for
> grid voltage.
>
>
> 73,
> Bill Smith KO4NR
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