RE: High voltage standing waves with a magnetron?

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Original poster: "Philip Chalk" <phil-at-apsecurity-dot-com.au> 


Hi,

Someone earlier suggested that the only way to stop the magnetron
drawing 'normal' current is to reduce the voltage a lot, which of course
kills the oscillation.

Frankly, I don't know enough about magnetrons to be authoritative, but I
would expect one to oscillate when fed from a current-limited supply of
the appropriate voltage.

I'm not suggesting it's simple, but it's certainly possible to build
such a supply.

If you only want milliwatts at microwaves, you may be better off
considering a reflex klystron, or maybe a TWT ?

One day I'm going to build a 'HERF' as you say, probably, but not
necessarily pulsed, running from 12V dc & mounted in/on my car.  Anyone
guess what it's for ???


Phil Chalk.


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, 3 February 2004 11:07 AM
To: tesla-at-pupman-dot-com
Subject: Re: High voltage standing waves with a magnetron?

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 01, 2004 6:35 PM
Subject: Re: High voltage standing waves with a magnetron?


  > Original poster: "mercurus2000" <mercurus2000-at-cox-dot-net>
  >
  > What if there isn't enough current? I was planning on powering it
with a
  > very small high voltage DC supply. I saw on one website a guy built a
  > handheld herf where the entire appratus fitted inside the magnetron
casing
  > and was powered by 4 D batteries, it of course was pulsed by charging
up a
  > small array of caps at 7000 volts, but it was safe enough for him to
hold
it
  > during operation and place his hand right above the transmitter.

Uh-huh... Sure, pulsed high power is reasonable, and would reduce the
average (but not peak) power of the magnetron.  What qualifications did
the
guy have for RF safety evaluation? I'm not talking about letters after
his
name, here, I'm talking real expertise in evaluting the hazards. I've
know
lots of very smart people who are absolutely ignorant about RF.  Did he
display any calculations showing field strengths or power density?

Any idiot can go hook up a HV power supply to a magnetron. Any idiot can
build a tesla coil.  Any idot can cook his hand or the lenses of his
eyeballs, almost painlessly. Any idiot can believe the stuff about "skin
effect" and cook their insides and get RF burns because "gosh it doesn't
hurt".