[Amps] Plate Choke Resonances

[Gary Schafer]

I have done the same. In finding series resonance that the shorted choke and
in circuit (no short) come out the same using a GDO.

But how do you distinguish a parallel resonance from a series resonance?

73
Gary  K4FMX

> -----Original Message-----
> From: Carl [mailto:km1h at jeremy.mv.com]
> Sent: Sunday, January 31, 2010 12:12 PM
> To: garyschafer at comcast.net; dezrat1242 at yahoo.com; 'Amps reflector'
> Subject: Re: [Amps] Plate Choke Resonances
> 
> By various methods over the decades, out of circuit, and the open and
> short
> procedure. Loosely coupled GDO, spectrum analyzer, and VNA. Note that in
> the
> cases where Ive had all 3 methods available at the same time there is
> close
> agreement.
> 
> Carl
> KM1H
> 
> ----- Original Message -----
> From: "Gary Schafer" <garyschafer at comcast.net>
> To: "'Carl'" <km1h at jeremy.mv.com>; <dezrat1242 at yahoo.com>; "'Amps
> reflector'" <amps at contesting.com>
> Sent: Sunday, January 31, 2010 11:54 AM
> Subject: RE: [Amps] Plate Choke Resonances
> 
> 
> > Carl,
> >
> > How did you measure the parallel resonance of the choke?
> > How did you determine the difference between parallel resonance and
> series
> > resonance?
> >
> > 73
> > Gary  K4FMX
> >
> >> -----Original Message-----
> >> From: amps-bounces at contesting.com [mailto:amps-
> bounces at contesting.com]
> >> On Behalf Of Carl
> >> Sent: Sunday, January 31, 2010 9:22 AM
> >> To: dezrat1242 at yahoo.com; Amps reflector
> >> Subject: Re: [Amps] Plate Choke Resonances
> >>
> >>
> >> ----- Original Message -----
> >> From: "Bill, W6WRT" <dezrat1242 at yahoo.com>
> >> To: "Amps reflector" <amps at contesting.com>
> >> Sent: Sunday, January 31, 2010 1:43 AM
> >> Subject: Re: [Amps] Plate Choke Resonances
> >>
> >>
> >> > ORIGINAL MESSAGE:
> >> >
> >> > On Sat, 30 Jan 2010 22:27:47 -0700, Larry Benko
> <xxw0qe at comcast.net>
> >> > wrote:
> >> >
> >> >>
> >> >>I just ran a simulation with a tube with a 3000 ohm impedance and
> >> 3000V
> >> >>peak AC on the plate connected to a 100uH plate choke at 10MHz.
> >> >
> >> > REPLY:
> >> >
> >> > The problem with your simulation is that the voltage is held to a
> >> > constant 3000 V. In the real world the "Tesla effect" will cause
> the
> >> > voltage to rise far higher and that is what causes the smoke.
> >> >
> >> > One real world experiment is worth a thousand simulations, IMO.  :-
> )
> >> >
> >> > 73, Bill W6WRT
> >> >
> >>
> >> Ive made it a point over the years to test any plate choke I could
> get
> >> my
> >> hands on and build those in magazine or Internet articles.
> >>
> >> Almost without fail the ones using larger than necessary diameter
> wire
> >> show
> >> a pronounced parallel resonance in or very close to a ham band. This
> >> makes
> >> me think that the builder went the brute force method to avoid smoke
> >> since
> >> #22 or 24 isnt needed at 1200-1500W which is what levels they were
> used
> >> in.
> >>
> >> Probably the simplest and cleanest 160-10M choke is the old Amp
> Supply
> >> version used in all their amps with real transmitting tubes. One size
> >> fits
> >> all. Tests in the 5KW+ LK-800C and other versions with the 3500V tap
> and
> >> three 3CPX800A7's show absolutely no heating problems on any band.
> This
> >> 90uh
> >> choke has 2 1/8" of #26 on an unglazed 3/4" ceramic form, more
> properly
> >> referred to as technical ceramic. Im no chemist but Ive been told
> that
> >> the
> >> porcelain glazed contain some amounts of metal??
> >>
> >> Anyway, the series resonances are 12.8 and 49mHz and the parallel
> ones
> >> are
> >> 13.0 and 27.2 mHz. A .001 and .01 uF bypass keeps any pesky RF out of
> >> the
> >> electrolytics and wiring. Naturally, on 160M the tank circuit is
> >> involved as
> >> part of the choke circuit as already mentioned on here many times
> over
> >> the
> >> years.
> >>
> >> Maybe I havent been involved with sufficient voltages and power, Ive
> >> stopped
> >> at 10KW in my commercial life,  but Ive yet to see a Tesla effect
> from a
> >> plate choke. Many times in the bandswitch or Tune cap for other
> reasons
> >> but
> >> nothing to do with choke resonances.
> >>
> >> Perhaps the closest Ive been to ham amp choke fireworks is the
> various
> >> Dentrons when run on 12M. Remove 4 turns from the top and all is
> well.
> >> The
> >> 1st generation Ameritrons used to do a nice display also when WARC
> was
> >> opened. While they were still figuring out a new design I simply
> >> installed a
> >> B&W 802 in order to get customers back on the air ASAP.
> >>
> >> Carl
> >> KM1H
> >>
> >>
> >>
> >>
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> >>
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