[Amps] GU-84B Conversion

[Carl]

Why?

No room for 3-500Z's or 4-400's?

Carl
KM1H


----- Original Message ----- 
From: "Bill Smith" <ko4nrbs at yahoo.com>
To: <amps at 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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