AM Microwave Oven Klystron

B

Brent Steven

Guest
To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

Of course, any work will be done at our own risk by our own
techncians.

Thank you,

Brent Stevens
TechPro Group
 
"Brent Steven"
To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?
Click to expand...

** The RF output is already modulated - at 50Hz.




.... Phil
 
On Thu, 26 Nov 2009 17:35:27 -0800 (PST), a7yvm109gf5d1@netzero.com
wrote:

On Nov 26, 7:35 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Brent Steven"



To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

** The RF output is already modulated - at 50Hz.

... Phil

..or 60Hz. Or is it double?
Click to expand...
60, or for PHil, 50, not double.

I think the OP should be able to draw a conclusion based on this.
 
On Thu, 26 Nov 2009 17:35:27 -0800 (PST), the renowned
a7yvm109gf5d1@netzero.com wrote:

On Nov 26, 7:35 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Brent Steven"



To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

** The RF output is already modulated - at 50Hz.

... Phil

..or 60Hz. Or is it double?
Click to expand...
Phil is likely right, and it's 50Hz (since the OP appears to be in
Sydney Australia). Magnetron ovens magnetrons are usually powered via
an unfiltered half-wave doubler, with or without a high frequency
chopper.

HOWEVER, if it's a modern type such as Panasonic inverter type, it may
be seeing a more steady voltage across the magnetron.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Nov 26, 7:35 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Brent Steven"



To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

** The RF output is already modulated - at 50Hz.

... Phil
Click to expand...
...or 60Hz. Or is it double?
 
There was a 5 page description in RF Design, mid 1990s, on using a 2.4
ghz ISM band maggie for ham radio video. It had 4 tubes in series
with the magnetron for modulation. I cant find the reference right
now but it is not hard to modulate one if ran on DC.

The other one that comes up is

Communications Quarterly's Winter 1991 issue has an article by WA6EXV

Most of them are very close to the 13 cm ham radio band and they have
been explored for EME (moonbounce to non hams)

The downside for EME is unless you turn the cathode off and allow it
to self heat once its running they have a very wide noise bandwidth on
top of the center frequency. On the order of 10 mhz when driven off
the 50/60 hz supply and pulsed. It goes down to 1-2 mhz without the
cathode lit.

When I was in college I read the magazine stuff and just could not
wait to duplicate the experiment, then I read up on microwave safety
and decided I like my corneas clear...

Steve
 
On Fri, 27 Nov 2009 11:35:04 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"Brent Steven"

To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?


** The RF output is already modulated - at 50Hz.




... Phil
Click to expand...
So, you say if I want to AM one at 300Hz, I simply need to plug a
store-bought oven into a custom made 120V AC power supply running at
that frequency?

How does this affect the efficiency of the magnetron, given it is
designed for 50/60Hz? Is the current requirement the same?

Would the output resemble sinewave modulation on a CRO, or look
chopped?

Thank you for your advice.

Brent Steven
 
On Nov 26, 10:06 pm, o...@uakron.edu wrote:
There was a 5 page description in RF Design, mid 1990s, on using a 2.4
ghz ISM band maggie for  ham radio video.  It had  4 tubes in series
with the magnetron for modulation.  I cant find the reference right
now but it is not hard to modulate one if ran on DC.
Click to expand...
March 1989, Pacholok, "A Microwave Oven to Amateur TV Transmitter
Conversion," pp48-55.

A clearer schematic (electrically identical to Pacholok)
by Bill Parker, W8DMR, was published in the Jan/Feb
1989 issue of Spec-Com.


The other one that comes up is

Communications  Quarterly's Winter 1991 issue has an article by WA6EXV

Most of them are very close to the 13 cm ham radio band and they have
been explored for EME (moonbounce to non hams)

The downside for EME is unless you turn the cathode off and allow it
to self heat once its running they have a very wide noise bandwidth on
top of the center frequency.  On the order of 10 mhz when driven off
the 50/60 hz supply and pulsed.   It goes down to 1-2 mhz without the
cathode lit.

When I was in college I read the magazine stuff and just could not
wait to duplicate the experiment, then I read up on microwave safety
and decided I like my corneas clear...
Click to expand...
Yep.


--
HTH,
James Arthur
 
Brent Steven schrieb:

So, you say if I want to AM one at 300Hz, I simply need to plug a
store-bought oven into a custom made 120V AC power supply running at
that frequency?

How does this affect the efficiency of the magnetron, given it is
designed for 50/60Hz? Is the current requirement the same?
Click to expand...
Hello,

you should think not only about the magnetron, but also about the
transformer supplying the magnetron. I think the magnetron is not
designed specially for 50/60 Hz, but the transformer is.
A transformer designed for 50 Hz will work with 60 Hz too, but not every
transformer for 60 Hz will work without problems with 60 Hz.
I saw a frequency generator from HP designed for 50/60 Hz power and also
400 Hz, but only at 110 V, not with 230 V nets.

Bye
 
On a sunny day (Fri, 27 Nov 2009 00:07:28 GMT) it happened
brentstevens@radgrah.com (Brent Steven) wrote in
<4b0f173c.1282453@news.tpg.com.au>:

To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

Of course, any work will be done at our own risk by our own
techncians.

Thank you,

Brent Stevens
TechPro Group
Click to expand...
Rotating vane in the wave guide.
 
"Brent Steven" claims he is from this mob in Australia:

http://www.protechgroup.com.au/

How embarrassment......


To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?


** The RF output is already modulated - at 50Hz.


So, you say if I want to AM one at 300Hz, I simply need to plug a
store-bought oven into a custom made 120V AC power supply running at
that frequency?
Click to expand...
** OK folks - we have ourselves here a *genuine* LIVE ONE !!!!!

This smug prick simply ain't content to stop at posting an embarrassingly
dopey question on a matter he is utterly clueless about - he actually
goes out of his way to show just how pig ignorant he really is.

But inserting his totally bonkers idea into another person's mouth.


How does this affect the efficiency of the magnetron, given it is
designed for 50/60Hz? Is the current requirement the same?
Click to expand...

** You figure it out PAL - since the bonkers concept is YOUR idea.


Would the output resemble sinewave modulation on a CRO, or look
chopped?
Click to expand...
** Being late on a Friday arvo, in sunny Queensland, when Mr Bent posted
this utter tripe - can I take an educated guess he was likely quite
pissed ????

But my generosity of mind may well be proved baseless.

I can hardly wait for the next instalment.



..... Phil
 
dagmargoodboat@yahoo.com wrote:
On Nov 26, 10:06 pm, o...@uakron.edu wrote:
There was a 5 page description in RF Design, mid 1990s, on using a 2.4
ghz ISM band maggie for ham radio video. It had 4 tubes in series
with the magnetron for modulation. I cant find the reference right
now but it is not hard to modulate one if ran on DC.

March 1989, Pacholok, "A Microwave Oven to Amateur TV Transmitter
Conversion," pp48-55.

A clearer schematic (electrically identical to Pacholok)
by Bill Parker, W8DMR, was published in the Jan/Feb
1989 issue of Spec-Com.


The other one that comes up is

Communications Quarterly's Winter 1991 issue has an article by WA6EXV

Most of them are very close to the 13 cm ham radio band and they have
been explored for EME (moonbounce to non hams)

The downside for EME is unless you turn the cathode off and allow it
to self heat once its running they have a very wide noise bandwidth on
top of the center frequency. On the order of 10 mhz when driven off
the 50/60 hz supply and pulsed. It goes down to 1-2 mhz without the
cathode lit.

When I was in college I read the magazine stuff and just could not
wait to duplicate the experiment, then I read up on microwave safety
and decided I like my corneas clear...

Yep.


--
HTH,
James Arthur
Click to expand...

Converting a magnetron into a klystron is a non trivial project.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
On Nov 26, 6:22 pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat>
wrote:
On Thu, 26 Nov 2009 17:35:27 -0800 (PST), the renowned



a7yvm109gf...@netzero.com wrote:
On Nov 26, 7:35 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Brent Steven"

To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

** The RF output is already modulated  -  at 50Hz.

...  Phil

..or 60Hz. Or is it double?

Phil is likely right, and it's 50Hz (since the OP appears to be in
Sydney Australia). Magnetron ovens magnetrons are usually powered via
an unfiltered half-wave doubler, with or without a high frequency
chopper.

HOWEVER, if it's a modern type such as Panasonic inverter type, it may
be seeing a more steady voltage across the magnetron.
Click to expand...
I think the inverter ones don't filter the rectified mains (at least
not very much). There would likely be a large modulation at twice the
mains. At least this is how the EMI from it sounds on a nearby radio.
 
Jan Panteltje wrote:

Rotating vane in the wave guide.
Click to expand...
Now that is very lateral :).

The last (dead) microwave oven I opened up to see if there were any
usefull parts had a constant voltage transformer driving a half wave si
rectifier stack with very little smoothing at the other side.

If you want to amplitude modulate the output, you may need to substitute
a full wave rectifier and more smoothing cap to get a more constant
supply and less fm to start. Not sure if the magnetron would need to be
derated, as the effective duty cycle would increase.

Jan's idea for amplitude modulation is probably the lowest cost and
easiest to try though, but you should expect some fm as the effective
load and vswr varies with fan position. I wonder if you could use a
circulator in path to reduce the effect of this ?.

Regards,

Chris
 
On Fri, 27 Nov 2009 00:07:28 +0000, Brent Steven wrote:

To conduct an experiment, we need to amplitude modulate the output of a
domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for a
one time use?

Of course, any work will be done at our own risk by our own techncians.

I've seen a series-modulated maggie - it used a 4-400A that was literally
Click to expand...
in series with the magnetron. It would be almost impossible to implement
this on a microwave the way they're connected in an oven, of course, but
it's doable - I don't know how "clean" the signal was, because it was
modulated with noise; it was a jamming transmitter in the USAF, so the
output was intended to be terribly noisy.

But, series modulation _will_ work; I just can't make any promises about
the quality of the output signal.

Good Luck!
Rich
 
On Fri, 27 Nov 2009 08:28:57 -0800 (PST), MooseFET
<kensmith@rahul.net> wrote:

On Nov 26, 6:22 pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat
wrote:
On Thu, 26 Nov 2009 17:35:27 -0800 (PST), the renowned



a7yvm109gf...@netzero.com wrote:
On Nov 26, 7:35 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Brent Steven"

To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

** The RF output is already modulated  -  at 50Hz.

...  Phil

..or 60Hz. Or is it double?

Phil is likely right, and it's 50Hz (since the OP appears to be in
Sydney Australia). Magnetron ovens magnetrons are usually powered via
an unfiltered half-wave doubler, with or without a high frequency
chopper.

HOWEVER, if it's a modern type such as Panasonic inverter type, it may
be seeing a more steady voltage across the magnetron.

I think the inverter ones don't filter the rectified mains (at least
not very much). There would likely be a large modulation at twice the
mains. At least this is how the EMI from it sounds on a nearby radio.
Click to expand...
Here's one schematic that would fall into the "not very much"
category:-

http://www.eletrodomesticosforum.com/downloads/microondas/Panasonic_NN-G62BH.pdf

(page 20).
 
On Nov 26, 4:07 pm, brentstev...@radgrah.com (Brent Steven) wrote:
To conduct an experiment, we need to amplitude modulate the output of
a domestic microwave oven at a continuous audio frequency.

Can anyone offer any suggestions on the best means to achieve this for
a one time use?

Of course, any work will be done at our own risk by our own
techncians.
Click to expand...
If you for some reason can't use a klystron (all you can afford is a
magnetron, frinst), consider removing the magnetron's permanent
magnets and winding coils to provide the magnetic field; you can then
modulate their current. This basically takes the tube in and out of
resonance, raising and dropping the output power. Slightly easier to
modulate high current/low voltage than the other way around.

Just a thought.


Mark L. Fergerson
 
"Chris Quack"
The last (dead) microwave oven I opened up to see if there were any
usefull parts had a constant voltage transformer driving a half wave si
rectifier stack with very little smoothing at the other side.
Click to expand...

** The AC supply tranny in a microwave oven is not a constant voltage
ype - maybe the copper shorting rings in the core might give someone that
mistaken impression.

Rectification is actually full wave, cos the magnetron itself acts as the
other diode in the doubler - while the AC supply current draw is close to
sine wave, rather than brief pulses at double line frequency as with most
PSUs.

The deliberately large leakage inductance in the supply tranny plays a
critical role in the operation of the circuit - as does the carefully
specified high voltage filter cap of only a uF or two.



..... Phil
 
Phil Allison wrote:
"Chris Quack"
The last (dead) microwave oven I opened up to see if there were any
usefull parts had a constant voltage transformer driving a half wave si
rectifier stack with very little smoothing at the other side.


** The AC supply tranny in a microwave oven is not a constant voltage
ype - maybe the copper shorting rings in the core might give someone that
mistaken impression.

Rectification is actually full wave, cos the magnetron itself acts as the
other diode in the doubler - while the AC supply current draw is close to
sine wave, rather than brief pulses at double line frequency as with most
PSUs.

The deliberately large leakage inductance in the supply tranny plays a
critical role in the operation of the circuit - as does the carefully
specified high voltage filter cap of only a uF or two.



.... Phil
Click to expand...
That's interesting. I can't remember if it had a resonating cap on the
transformer, so perhaps that's how it worked. There was the usual cvt
gap in the core, but don't doublers usually need two caps as well as 2
diodes ?...

Regards,

Chris
 
"Chris Quack"


** Kindly drop dead ..........

Fuckwit.




..... Phil
 
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