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Re: [Amps] GS35B Amp 15 m Situation

To: craxd1@verizon.net, amps@contesting.com
Subject: Re: [Amps] GS35B Amp 15 m Situation
From: Mike <k4gmh@arrl.net>
Date: Mon, 03 Jul 2006 07:34:37 -0400
List-post: <mailto:amps@contesting.com>
Hello Will,

Thanks for the suggestion on checking the bandswitch as each band has 
a separate position.  I'll do that and get back to you.

Each band has a separate pi input circuit matched to the tube under 
operating conditions.



At 11:52 PM 7/2/2006, Will Matney wrote:
>Mike,
>
>Did you check the bandswitch contacts for these two frequencies? Do 
>you have a seperate input match for each frequency that's switched?
>
>Best,
>
>Will
>
>*********** REPLY SEPARATOR  ***********
>
>On 7/2/06 at 11:45 PM Mike wrote:
>
> >Hello,
> >
> >Having an issue with a homemade GS35B operationon 15 and 17 m.  When
> >keyed, the power seems to hesitate before going up to 1.5 KW
> >output.  CW is a mess on these bands due to this situation.  On RTTY
> >the power hesitation is so short that it doesn't present a
> >problem.  Amp. seems to be okay to about 1200 W, but the hesitation
> >returns above this level.  Other bands, 10, 20, 40, 80, 160 work okay.
> >
> >Using a TIP147 transistor in a bias circuit similar to Ian's Triode
> >Board bias circuit.  Cut-off bias is provided by a 10 KOhm resistor.
> >
> >The filament choke is ~25 bifilar turns of #16 on a 10"X1"X1/4"
> >oblong ferrite rod.  An additional choke of 20 turns #20 on a ferrite
> >rod, 3.5" long and 3/8" dia., is in the line from the filament
> >secondary center tap to the bias circuit.
> >
> >This a strange situation as seen on 17 and 15 meters using either an
> >antenna or a dummy load.   On the other bands, the power smoothly
> >rises to full output.
> >
> >Any ideas on how to fix this situation are appreciated.
> >
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> >http://lists.contesting.com/mailman/listinfo/amps

         73,
         Mike, K4GMH 
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