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Re: [Amps] GS35B Amp 15 m Situation

To: "Mike" <k4gmh@arrl.net>, amps@contesting.com
Subject: Re: [Amps] GS35B Amp 15 m Situation
From: "Will Matney" <craxd1@verizon.net>
Reply-to: craxd1@verizon.net
Date: Sun, 02 Jul 2006 23:52:12 -0400
List-post: <mailto:amps@contesting.com>
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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