[Amps] Using automatic tuner for Amp input

[Gary Schafer]

Bill Orr recommends around 13 pf per meter for the input capacitor. At 160
meters that would be 2080 pf.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Alek Petkovic
> Sent: Sunday, August 29, 2010 8:07 AM
> To: Fuqua, Bill L; jeff millar; Amps at contesting.com
> Subject: Re: [Amps] Using automatic tuner for Amp input
> 
> I forgot to add. This amp is a 160 - 10m job so we're really gonna
> have some big Farads sittin' there, aren't we?
> 
> 73, Alek.
> 
> 
> At 09:04 PM 29/08/2010, Alek Petkovic wrote:
> >G'day Bill,
> >
> >I just did a few calcs. We are gonna use the LDG 100AMP tuner in a gs35B
> amp.
> >
> >Let's assume it's 100 ohms. We need a cap whose Xc on 3.5MHz = 25 ohms.
> Xc =
> >1/2.pi.f.C, So C = 1820pF.
> >
> >Forgive me mate but that sounds like a bloody big capacitor to have
> >sitting on the input at 10m.
> >
> >Even with 50 Ohm tube input impedance, we are looking at 900pF sitting
> there.
> >
> >Did I do something wrong or is this all ok?
> >
> >Thanks and 73,
> >Alek.
> >
> >
> >
> >At 02:15 AM 29/08/2010, Fuqua, Bill L wrote:
> > >You can make it work as long as you shunt the input of the amplifier
> > >with a capacitor with a reactance of 1/4 or less of the input
> > >impedance. This will provide the charge storage needed to smooth out
> > >the sinusoidal wave from and the antenna tuner will still match the
> > >impedance. I prefer a Q of 10 or better myself but if you chose 1/4
> > >for 80 meters you will have a Q of 4 on 80 meters and on 10 meters
> > >it will be 32 with out switching capacitors.
> > >
> > >73
> > >Bill wa4lav
> > >
> > >________________________________________
> > >From: amps-bounces at contesting.com [amps-bounces at contesting.com] On
> > >Behalf Of jeff millar [jeff at wa1hco.net]
> > >Sent: Saturday, August 28, 2010 11:31 AM
> > >To: Amps at contesting.com
> > >Subject: [Amps] Using automatic tuner for Amp input
> > >
> > >What do people think of the amplifier by Bill W4NFR shown in the
> > >latest QEX?  It
> > >uses an LDG tuner on the amplifier input instead of a set of
> filter/matching
> > >networks for each band.  It seems like an innovative design.
> > >
> > >jeff, wa1hco
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> >
> >
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