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@comcast.net>
To: "'Carl'" <km1h@jeremy.mv.com>; <dezrat1242@yahoo.com>; "'Amps
reflector'" <amps@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@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
>>
>>
>>
>>
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>>
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>
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