I have never tried it but I saw a warning against terminating the choke
leads with a closed loop/strap. It was either in one of Orr's handbooks or a
late ARRL handbook. Maybe on Rich Measures page??
73
Gary K4FMX
> -----Original Message-----
> From: Carl [mailto:km1h@jeremy.mv.com]
> Sent: Wednesday, March 24, 2010 4:37 PM
> To: garyschafer@comcast.net; 'Vic K2VCO'; amps@contesting.com
> Subject: Re: [Amps] Plate chokes (was: Re: placement of RF choke bypass
> cap.)
>
> Heath had no problems with a shorted bottom end in any of their SB
> series of
> amps, TX, or Xcvrs.
>
> Running a loop up from the bottom may be one way of finding a sweet spot
> of
> minimum RF. Never tried it but it sounds interesting to experiment....at
> low
> power for starters!
>
> Carl
> KM1H
>
>
>
>
> > Vic,
> >
> > Don't put a shorted strap around the choke. It will look like a
> shorted
> > turn
> > and cause excessive current in the choke which may burn a section of
> the
> > choke out.
> >
> > Somewhere I read that you should not use a continuous band around
> either
> > end
> > to terminate the ends of the choke winding. Same thing happens.
> >
> > 73
> > Gary K4FMX
> >
> >> -----Original Message-----
> >> From: amps-bounces@contesting.com [mailto:amps-
> bounces@contesting.com]
> >> On Behalf Of Vic K2VCO
> >> Sent: Wednesday, March 24, 2010 11:07 AM
> >> To: amps@contesting.com
> >> Subject: [Amps] Plate chokes (was: Re: placement of RF choke bypass
> >> cap.)
> >>
> >> On 3/24/2010 5:18 AM, DF3KV wrote:
> >> > I tried that [RF Parts] choke in one of my amplifiers without
> testing
> >> it first with the
> >> > GDO and it just turned into smoke on 10m.
> >>
> >> I've been working on a choke for a new amplifier project. I've
> noticed
> >> some things which
> >> experienced builders probably already know, but I thought would be
> worth
> >> mentioning:
> >>
> >> a) Even if the gdo has decent calibration to begin with and even if
> you
> >> are careful to use
> >> it properly (move it away from the choke to get the smallest
> perceptible
> >> dip) the
> >> frequency is pulled a lot near a resonance. I've found it necessary
> to
> >> use it together
> >> with a counter to get accurate, repeatable measurements.
> >>
> >> b) It makes a big difference when the choke is mounted on a chassis
> (and
> >> probably when it
> >> is inside a box) compared to sitting on a wooden workbench.
> >>
> >> I am trying out an idea as follows: I wrapped the choke with Teflon
> tape
> >> and made a copper
> >> band about 1/4" in width which I can slide up and down. The plan is
> to
> >> test the choke
> >> installed and wired with everything mounted and use this to fine tune
> it
> >> before applying
> >> power.
> >>
> >> For what it's worth my choke is 3-7/8" close wound no. 28 on a 1"
> >> diameter ceramic form.
> >> I've used the RF Parts choke before successfully, but why pay for
> >> something that you can
> >> make for nothing?
> >> --
> >> Vic, K2VCO
> >> Fresno CA
> >> http://www.qsl.net/k2vco/
> >> _______________________________________________
> >> Amps mailing list
> >> Amps@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
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