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@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Carl
> Sent: Sunday, January 31, 2010 9:22 AM
> To: dezrat1242@yahoo.com; Amps reflector
> Subject: Re: [Amps] Plate Choke Resonances
>
>
> ----- Original Message -----
> From: "Bill, W6WRT" <dezrat1242@yahoo.com>
> To: "Amps reflector" <amps@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@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
>
>
>
>
> _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|