Rahul Sathe wrote:
> 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.
>
Pills? Are those for the headache when it doesn't work?
73
Roger (K8RI)
> 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
>>>
>>>
>>
>>
>>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|