[Amps] Subject: grounding grids

[Jack Shirley]

Yes,  the RF choke is for DC return only.

Jack N8DX

On Mon, Aug 3, 2009 at 1:45 AM, Joe Subich, W4TV <lists at subich.com> wrote:

>
> > I am asking why he thought that, because we are talking about
> > the Drake L4 amplifier
>
> No, we were talking about the SB-220 and the RF choke has such
> a high value (1 mH) that it is an open circuit compared to the
> capacitors.
>
> 73,
>
>   ... Joe, W4TV
>
>
>
>
> > -----Original Message-----
> > From: amps-bounces at contesting.com
> > [mailto:amps-bounces at contesting.com] On Behalf Of Gary Schafer
> > Sent: Sunday, August 02, 2009 10:01 PM
> > To: 'Herzog'; 'Ham-amps'
> > Subject: Re: [Amps] Subject: grounding grids
> >
> >
> > No red herring here. Joe made the statement that "the
> > impedance between grid and common changes by a factor of 10:1
> > between 3.5 and 29.7 MHz".
> >
> > I am asking why he thought that, because we are talking about
> > the Drake L4 amplifier with the grid chokes and grid bypass
> > capacitors which are reported to be there to provide an
> > amount of negative feedback, over that frequency range. If
> > only the bypass capacitors impedance is considered then that
> > may be true. BUT, there is also a choke between the grids and
> > ground which will modify any constant change in impedance.
> >
> > 73
> > Gary  K4FMX
> >
> > > -----Original Message-----
> > > From: amps-bounces at contesting.com
> > [mailto:amps-bounces at contesting.com]
> > > On Behalf Of Herzog
> > > Sent: Sunday, August 02, 2009 7:15 PM
> > > To: Ham-amps
> > > Subject: Re: [Amps] Subject: grounding grids
> > >
> > > Since I subscribe to the general story that the grounding strap and
> > > internal connection to the tube acts as an inductor, the
> > impedance is
> > > = to a constant times the inductance times the frequency;
> > which is a
> > > ratio of about 30 to 3 MHz, or a ten to one ratio. I know that it
> > > would actually act as a complex transmission line, but
> > engineers like
> > > to simplify life.  Old slide rule mentality, etc.  K2LB Wil
> > > ==============================
> > > RE:  What makes you think that the impedance between the grid and
> > > common changes by a factor of 10:1 between 3.5 and 29.7 MHz? 73
> > > Gary K4FMX
> > > =============
> > > That is a red herring.  Because the frequency ratio is
> > about 10 to one
> > > is the answer.
> > >      This begs the question as to whether the impedance is
> > enough to care
> > > about, and cap or inductive,  or a series resonance.  Such wonderful
> > > considerations are why we can discuss this matter after
> > over 50 years.
> > > Wil
> > > _______________________________________________
> > > Amps mailing list
> > > Amps at contesting.com
> > > http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>