[Amps] Tuned Input

[rlm]

ur welcome.  350 for C-in should not be that bad.  To change the matching 
ratio of a Pi, at least two reactances need to be adj.

>The schematic calls the input Cap for 20 350pF, I supposeits value could
>have changed over the years, assuming it was correct to begin with.
>
>Thanks.
>
>Rick.
>----- Original Message -----
>From: "rlm" <2 at vc.net>
>To: "Davis_R" <WD8JJA at arrl.net>; " AMPS" <amps at contesting.com>
>Sent: Monday, March 10, 2003 10:37 AM
>Subject: Re: [Amps] Tuned Input
>
>
>>
>>
>> >Hmmm, 'minimum is under 1.2 to 1' ? that makes me wonder --
>> >
>> >1.2 to 1 seems pretty tight, what would the VSWR bandwidth be?
>> >
>> **  beats me but some solid-state transceivers begin to throttle back c.
>> 1.2:1.
>>
>> >Makes me ask a question -- I have an FL-2100B, I bought it used and it
>seems
>> >to work FB, but I checked the input coil alignment and found one band (20
>m
>> >if memory serves me correctly) that I could not bring down low enough to
>> >really make me happy. I think it was 2 - 3 to 1 at best.  (I don't think
>any
>> >were as low as 1.2 to 1). What do I look at to improve this?
>>
>> **  Increase the Q of the tuned input by increasing C-in, C-out, and
>> decreasing L.  For 20m, a C-in of c. 390pF should do ok.
>>
>> > Is it likely
>> >to be the adjustable inductor? Or would it be easier to replace one or
>both
>> >or the tuned input capacitors?
>>
>> **  C-out and L need to be adjustable.  When you arrive at something that
>> works, replace the adjustable C with a fixed unit.
>> >
>> cheers, Rick
>>
>>
>> >----- Original Message -----
>> >From: "rlm" <2 at vc.net>
>> >To: "Ed" <edw3nr at nexband.com>; " AMPS" <amps at contesting.com>
>> >Sent: Sunday, March 09, 2003 7:00 PM
>> >Subject: Re: [Amps] Tuned Input
>> >
>> >
>> >>
>> >>
>> >> >I want to make sure I am right here. Tune the input for best SWR
>> >>
>> >> **  Yes, provided the minimum is under 1.2 to 1.  If it's not, the Q of
>> >> the tuned input needs to be pumped up,
>> >>
>> >> >and maximum
>> >> >Grid current or ????????? ...........73
>> >> >
>> >> **  Tune for max RF out with whatever drive level produces the rated
>max
>> >> anode current.  Max out always results in a reasonable amount of
>> >> grid-current because if too many electrons are diverted to the grid,
>> >> fewer electrons arrive at the anode and output drops.
>> >>
>> >> cheers, Ed
>> >>
>> >> -  R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
>> >> www.vcnet.com/measures.
>> >> end
>> >>
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>>
>> -  R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
>> www.vcnet.com/measures.
>> end
>>
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-  R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K, 
www.vcnet.com/measures.  
end