If you have a small antenna tuner, it can be used to reduce the vswr for
test purposes.
73,
Gerald K5GW
In a message dated 9/8/2009 11:59:00 A.M. Central Daylight Time,
vu3raz@gmail.com writes:
I will try that tomorrow don. For the input circuit does nothing on 14 MHz
VSWR is nowhere near 2.
I am thinking of ripping the input tuned circuit and replacing it with a
simple parallel resonant ckt as in the eimac design.
Rahul
On Tue, Sep 8, 2009 at 9:59 PM, Paul Playford <paul@w8aef.com> wrote:
> Richard Measures, AG6K, has done a lot of work on SB-220s and talks about
> the input circuit at:
>
> http://www.somis.org/SB220ci.html
>
> FWIW, Richard has his detractors however I have applied his modifications
> to several SB-220s and a Henry 2K with great success.
>
> de Paul, W8AEF
>
> ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5D
>
> ----- Original Message ----- From: "Rahul Sathe" <vu3raz@gmail.com>
> To: <amps@contesting.com>
> Sent: Tuesday, September 08, 2009 8:32 AM
> Subject: [Amps] SB221 Low Power Help
>
>
>
> Hello Experts,
>>
>> My name is Rahul call VU3RAZ. This is my first post to the list. I am
>> seeking help on fixing my old SB221.
>>
>> as such the amp works on all bands, no arc or parastatics, tuning and
>> loading is smooth and easy.. I am not able to load the amp to full rated
>> plate current even with a 100 W drive with my 756 Pro3. Input VSWR is
>> high,
>> I tried tuning the input tuned circuit but no luck on few bands (20,
15).
>> With the 756 ATU the things improve but I can not get plate current
beyond
>> ~
>> 400 mA. Even tried disconnecting HT from each tube to see if one if the
>> 3-500 is dead... both work but even with single tube I am not able to
load
>> the amp fully. Am I looking at dead (weak) tubes ... can both of them
show
>> exact same behavior? Or I am missing something I am not sure if I need
to
>> re
>> build the PSU (replace caps)
>>
>> Please help...
>>
>> 73
>> DE VU3RAZ
>>
>>
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