> One problem with PIN's is if the RF voltage
>the PIN is subjected to in its "off" state exceeds the
>bias applied to the PIN to turn it off, the RF voltage will
>attemp to turn the PIN back on.
> In the limited ampunt of PIN diode work I've done here
>it seems the PIN "off bias" should be at least twice the
>applied RF voltage if any sort of SWR may be
>present. So in a 50 ohm circuit at 1500 watts you'd need
>about 5-600 volts reverse bias.
** 1500W into 50-ohms =s c. 775v p-p. To prevent a PIN diode from
conducting at any point during the cycle, at least 800v of reverse bias
is needed, provided the SWR was 1 to 1, otherwise the PIN diode could
short.
>. In a Hi-Z cicuit such
>as a plate tank I.E. 2000 ohms, you'd need about 3500 volts.
>Thats a tall order.
>
** indeed, Mark.
>
>
>On Wed, 18 Jun 03 13:10:12 -0700 2 <2@vc.net> writes:
>> >Hi Rich,
>> >
>> >PINs are readily available to 1000Vpk and of course can be placed
>> in series
>> >for higher voltage applications.
>>
>> ** Hello, Steve -- For 10kW @ 50-ohms, a minimum piv of 2000v is
>> needed.
>>
>> >Remember, a PIN is not a P-N junction
>> >device and doesn't really have a "PIV" rating...when biased OFF,
>> its a large
>> >value resistor and when biased ON, it's a small value
>> resistor....using
>> >power devices that can be biased ON with amperes of current, that
>> resistor
>> >can become *really* small......-WB2WIK/6
>> >
>> >"Success is the ability to go from failure to failure with no loss
>> of
>> >enthusiasm." -Winston Churchill
>> >
>> >> -----Original Message-----
>> >> From: 2 [SMTP:2@vc.net]
>> >> Sent: Tuesday, June 17, 2003 7:15 AM
>> >> To: Dr. William J. Schmidt, II; on4kj; AMPS
>> >> Subject: Re: [Amps] electronic switching
>> >>
>> >> >Well, we do..... there are diodes that will handle as much as
>> 10kW....
>> >> but
>> >> >they are expensive. Harris uses them in their gear...
>> >> >
>> >> ** What is the piv rating of such diodes, William?
>> >>
>> >> >Sincerely,
>> >> >
>> >> >Dr. William J. Schmidt, II K9HZ
>> >> >
>> >> >"Collector of Edison Wind-up Phonographs... Do you have one for
>> me?"
>> >> >Email: bill@wjschmidt.com
>> >> >Alternate Email: wmschmidt@charter.net
>> >> >WebPage: www.wjschmidt.com
>> >> >
>> >> >
>> >> >
>> >> >----- Original Message -----
>> >> >From: "on4kj" <on4kj@skynet.be>
>> >> >To: <amps@contesting.com>
>> >> >Sent: Sunday, June 15, 2003 2:44 PM
>> >> >Subject: [Amps] electronic switching
>> >> >
>> >> >
>> >> >> Hello Folks,
>> >> >>
>> >> >> About steatite wafers used for band switching.
>> >> >> Why dont we see switching systems based on pindiode, for input
>> ( 100 w
>> >> )
>> >> >> must be possible nowadays. Even for high output power !!
>> >> >> What say ?
>> >> >>
>> >> >> Jos on4kj
>> >> >>
>> >> >>
>> >> >> ----- Original Message -----
>> >> >> From: "Osten B Magnusson" <sm5dqc@algonet.se>
>> >> >> To: <amps@contesting.com>
>> >> >> Sent: Saturday, June 14, 2003 10:35 AM
>> >> >> Subject: [Amps] 572B's WARNING
>> >> >>
>> >> >>
>> >> >> >
>> >> >> >
>> >> >> > STAY AWAY FROM RICHARDSON ELECTRONICS, ENGLAND
>> www.rell.com
>> >> >> >
>> >> >> > 572B's are sold here in Europe by different dealers, the
>> tubes are
>> >> >> distributed by Richardson Electronics in England, and they
>> claim that
>> >> it's
>> >> >> Cetron tubes manufactured for National. Sorry to tell, but it
>> isn't the
>> >> >> truth - it's newly produced Chinese tubes re-badged by
>> Richardsons as
>> >> >> National and also have ''Made in USA'' printed on them. So be
>> careful,
>> >> >> before buying. I have been offered, not by Richardsons, but by
>> the
>> >> >> distributor to get a full refund if sending the tubes back.
>> Richardsons
>> >> >does
>> >> >> not even answer e-mails...
>> >> >> >
>> >> >> > This is part of an e-mail from a serious distributor in
>> England:
>> >> >> >
>> >> >> > >>Hello Osten,
>> >> >> > >>Taylor is a brand name for RF parts but these can be
>> re-badged
>> >> >any
>> >> >> type!
>> >> >> > >>We have National 572B which are badged by Richardsons
>> which is
>> >> >the
>> >> >> main
>> >> >> > >>outlet for Eimac, but need not be Eimac !
>> >> >> >
>> >> >> > There are original Cetron NOS 572B's available here in
>> Europe, have a
>> >> >look
>> >> >> at www.clhi-fi.it It's in Italian, but click on
>> ''Surplus'' and
>> >> than
>> >> >> ''avanti'' to go to page four. There are no prices on the WEB,
>> but in
>> >> an
>> >> >> e-mail they asked 500 ''euros'' for a matched pair, plus
>> postage.
>> >> That's
>> >> >> totally USD 645 for a matched pair!!! I know that there are
>> also NOS
>> >> >> Cetron 572B's available in USA, but unfortunately we have to
>> pay more
>> >> >> postage, customs, 25 percent VAT etc. so here we always try to
>> buy from
>> >> a
>> >> >> European Community country, this was no customs and other
>> extra charges
>> >> to
>> >> >> pay.
>> >> >> >
>> >> >> > Probably time to get all ''glass tubes'' amplifiers marked
>> ''junk''
>> >> and
>> >> >in
>> >> >> the future only get amplifiers with ceramic tubes!
>> >> >> >
>> >> >> > 73 de Osten SM5DQC e-mail: sm5dqc@algonet.se
>
>
>________________________________________________________________
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>
Rich, AG6K, 805-386-3734, www.vcnet.com/measures
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