Thanks for the post Jay,
VSWR "high" is above 2... particularly on 20 and 15. the same can not be
tuned with the stock input coils. On other bands it is well matched...
mostly below 1.2.
If I ignore the current reading... and look in my "Bird" on CW or RTTY tone
it reads max 400 to 450W for a ~100 W drive. Of course I can live with low
power... but not with a faulty(?) amp that too like SB 221 !
Well I also have a Solid State with 4 pills that can do better than present
221 @ 60 to 80W input.
73 Rahul
On Wed, Sep 9, 2009 at 9:03 PM, Jay Musikar <af2c@yahoo.com> wrote:
> GM/GE Rahul -
>
> I would think that the group might need more information:
>
> 1. You state high input VSWR. Please define "high."
> 2. Let's forget the current reading for the moment and let us know what
> the output of the amp with about 100W of drive.
>
> The metering on the SB220/221 is notorious for inaccurate over the years.
> Replacement of the metering board or component resistors is not uncommon,
> but in many cases we live with it by careful tuning and a Watt meter.
>
> You really may not have a problem.
>
> 73,
> Jay/AF2C
>
>
> --- On Tue, 9/8/09, Rahul Sathe <vu3raz@gmail.com> wrote:
>
> > From: Rahul Sathe <vu3raz@gmail.com>
> > Subject: [Amps] SB221 Low Power Help
> > To: amps@contesting.com
> > Date: Tuesday, September 8, 2009, 11:32 AM
> > 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
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
>
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