cliff wright wrote:
snip

2. I would be quite sure that an 807 based linear would turn into slag
with 2Kv on the plates,...

Please see http://www.cybertheque.org/homebrew/837_linear

This design is not mine but I documented the layout, construction,
and circuitry of a quad 807 (837) linear from silent key
K9KLN. It used a 2KV power supply

Regards,

Michael

"msg" wrote in message
...
cliff wright wrote:
snip

2. I would be quite sure that an 807 based linear would turn into slag
with 2Kv on the plates,...

Please see http://www.cybertheque.org/homebrew/837_linear

This design is not mine but I documented the layout, construction,
and circuitry of a quad 807 (837) linear from silent key
K9KLN. It used a 2KV power supply

Regards,

Michael

How are the cathodes returns supplied?

Pete

"cliff wright" wrote in message
...
Jimmie D wrote:
"Jimmie D" wrote in message
...

"Jimmie D" wrote in message
. ..

"msg" wrote in message
...

Jimmie D wrote:


there are appaently 2 types, one is made to run off of 12 volts maybe
24 VDC and the other runs off of 120VAC.
I think the 120VAC initially converts it to 300VDC then aplies it to
the inverter circuit.. Still trying to find a schematic to verify. I
would think this technology could be a major help for amp builders
allowing us to build inexpensive power supplies and easily custom wind
the inverter transformers.

Please dig out the ones you have and take photos, front and rear of the
entire unit and if you don't mind, disassemble and photograph and
components. I can host the photos if you wish (email them to me).
This would _really_ help in the evaluation until any of us find
schematics.

Regards,

Michael
msg _at_ cybertheque _dot_ org

Seems i am going to be looking for a couple more as the wife laid claim
on these.


I did find some info saying the switcher was run using IGBTs.



Rats, service manual just shows it as a box, but I did find some useful
info here

http://fusor.net/board/view.php?site...y=115878692 1

Knowing the freq they switch at would be a big help


Jimmie
I must confess that I'm not familiar with "inverter" type PSU's for
microwaves. However judging by the old type you would literally be
"playing with fire" in using them for a TX PSU.
Based on the "Don't put it in unless it's needed" philosophy it
1. Won't have ANY filtering worth mentioning. In fact the output will
probably be a series of rough square waves giving about +2KV average
voltage.
2. I would be quite sure that an 807 based linear would turn into slag
with 2Kv on the plates, let alone 2KV squarewaves at about 25KHz.

This is based on the fact that microwave ovens use cavity magnetrons.
these need a small heater voltage and a beefy but rough HT supply.
They are just a diode in a powerful transverse magnetic field.
After all your coffee or soup isn't a sensitive soul about signals!

Now if you had a linear needing 2Kv or so (maybe a California Kilowatt!!!)
and a good supply of high voltage caps then you might be getting somwhere.
You would indeed have the advantage of needing less smoothing because of
the high switching frequency of the inverter but any choke would have to
be suitable for 30 KHz at least with powerful insulation.
But with decent TX tubes not being cheap I still reckon I would prefer one
of the old HV transformers with plenty of fuses.
Best of luck!
73's ZL1BDA ex G3NIA.

Basically I want it for educational(my education) purposes. I had to give up
the ovens I got at the goodwill to my wife so I am waiting on another one to
show up..Bsically I want out learn about the design of the power supply. I
figure it can be much improved but dont see why the idea of using a n
inverter would not work for rf amps. I want to learn about the magnetics
used and the operating frequency to hopefully design my own inverter type
power supply. I was thinking of something along the lines of the old 12 to
600volt inverters used by HEath for their old mobile rigs. But I want to use
them off the mains, input 300vdc output up to a couple of KV. Presently I
have a couple of inverter transformers salvaged from some old tube type CB
amps and the plan is drive them with a couple of IGBTs. First I need to get
them operatin as designed so I can figure out for what freq they were
designed.



Jimmie

msg wrote:
cliff wright wrote:
snip

2. I would be quite sure that an 807 based linear would turn into slag
with 2Kv on the plates,...


Please see http://www.cybertheque.org/homebrew/837_linear

This design is not mine but I documented the layout, construction,
and circuitry of a quad 807 (837) linear from silent key
K9KLN. It used a 2KV power supply

Regards,

Michael
Had a look at the old quad GG 807 type linear.
COR! that's a real old bit of ham radio.
My own experience with 1625/807's is that with more than 1KV on the
plate they didn't survive long. Any mismatch or offtuning and flashover
happened pretty fast. Back in the 1960's I had quite a bin full of duds
that went just that way.
Recently I had a fault in my modified kenwood 820s which destroyed 2x
6146B's in a similar way. That's with only 850v plate voltage too.
However it is true that linear amps tend to work better in a high
voltage/low current mode, provided the finals can take it.
My old home brew 100watt linear used a TT21 (KT88 with a top cap plate)
and that worked fine with 1050 volts. Nice and linear and 66% effecient
on 14 Mhz (measured).
I once built an 811A GG linear but never needed the extra power so it
nevergot on the air.
Regards Cliff Wright ZL1BDA

Had a look at the old quad GG 807 type linear.
COR! that's a real old bit of ham radio.
My own experience with 1625/807's is that with more than 1KV on the
plate they didn't survive long. Any mismatch or offtuning and flashover
happened pretty fast. Back in the 1960's I had quite a bin full of duds
that went just that way.
Recently I had a fault in my modified kenwood 820s which destroyed 2x
6146B's in a similar way. That's with only 850v plate voltage too.
However it is true that linear amps tend to work better in a high
voltage/low current mode, provided the finals can take it.
My old home brew 100watt linear used a TT21 (KT88 with a top cap plate)
and that worked fine with 1050 volts. Nice and linear and 66% effecient
on 14 Mhz (measured).
I once built an 811A GG linear but never needed the extra power so it
nevergot on the air.
Regards Cliff Wright ZL1BDA
=====================================
Re the anode voltage used for PA valves ; the older (1968-1973
generation) Yaesu transceivers (FT 40x & 50x)using TV Line Sweep valves
(tubes) had 2 HV voltage transformer taps resulting in either 650 or
850V-DC .
I always used 650V since 850V caused the valves to be too hot ,due to
the limited (1 small fan ) cooling .
Although I have seen designs including 4 line sweep valves in
parallel,running on 1000 or even 1250 V ,but only with enhanced cooling.

When licenced in 1985 my first transceiver was a FT400 , an excellent
learning piece of kit,involving some 'fried' PA valves.

Frank GM0CSZ / KN6WH

On Aug 5, 8:15 am, Highland Ham
wrote:
Had a look at the old quad GG 807 type linear.
COR! that's a real old bit of ham radio.
My own experience with 1625/807's is that with more than 1KV on the
plate they didn't survive long. Any mismatch or off-tuning and flashover
happened pretty fast. Back in the 1960's I had quite a bin full of duds
that went just that way.
Recently I had a fault in my modified kenwood 820s which destroyed 2x
6146B's in a similar way. That's with only 850v plate voltage too.
However it is true that linear amps tend to work better in a high
voltage/low current mode, provided the finals can take it.
My old home brew 100watt linear used a TT21 (KT88 with a top cap plate)
and that worked fine with 1050 volts. Nice and linear and 66% efficient
on 14 Mhz (measured).
I once built an 811A GG linear but never needed the extra power so it
nevergot on the air.
Regards Cliff Wright ZL1BDA

=====================================
Re the anode voltage used for PA valves ; the older (1968-1973
generation) Yaesu transceivers (FT 40x & 50x)using TV Line Sweep valves
(tubes) had 2 HV voltage transformer taps resulting in either 650 or
850V-DC .
I always used 650V since 850V caused the valves to be too hot ,due to
the limited (1 small fan ) cooling .
Although I have seen designs including 4 line sweep valves in
parallel, running on 1000 or even 1250 V ,but only with enhanced cooling.

When licenced in 1985 my first transceiver was a FT400 , an excellent
learning piece of kit, involving some 'fried' PA valves.

Frank GM0CSZ / KN6WH- Hide quoted text -

- Show quoted text -

Interesting about 'Inverter' power supplies in domestic microwave
ovens.
Here in this part of Canada have never knowingly seen one that was not
115 volt AC input.
I guess one could call them 'Switching power supplies'?
Our appliances have therefore been pretty heavy and usually with the
transformer mounted inside towards one end.
Several owned and subsequently a number scrapped have all had 60 cycle
transformers.
Have read that the transformers go into saturation each half cycle?
It appears that one end of the HV secondary of the transformers is
often grounded to the frame of the transformer.
However often thought that the substantial 60 Hz. transformers would
be the basis for good (non portable) PA power supplies.

"terry" wrote in message
oups.com...
On Aug 5, 8:15 am, Highland Ham
wrote:
Have read that the transformers go into saturation each half cycle?
It appears that one end of the HV secondary of the transformers is
often grounded to the frame of the transformer.
However often thought that the substantial 60 Hz. transformers would
be the basis for good (non portable) PA power supplies.


A ground secondary would mean a half-wave rectifier, which would
place a heavy DC bias on the core and might lead to core saturation long
before the full capacity of the transformer is reached..
Hammond derates their transformers by .28 for halfwave rectification
with capacitor input filtering. I think the current is also limited
by a magnetic shunt on the core (removeable, I think..)

If these new inverter supplies use a higher frequency and smaller
toroidal type core, that might open the possibility for easier
mods for ham use. I'd think it would have been featured in one
of the more technical ham magazines by now, though..

Pete

"Uncle Peter" wrote in message
...

"terry" wrote in message
oups.com...
On Aug 5, 8:15 am, Highland Ham
wrote:
Have read that the transformers go into saturation each half cycle?
It appears that one end of the HV secondary of the transformers is
often grounded to the frame of the transformer.
However often thought that the substantial 60 Hz. transformers would
be the basis for good (non portable) PA power supplies.


A ground secondary would mean a half-wave rectifier, which would
place a heavy DC bias on the core and might lead to core saturation long
before the full capacity of the transformer is reached..
Hammond derates their transformers by .28 for halfwave rectification
with capacitor input filtering. I think the current is also limited
by a magnetic shunt on the core (removeable, I think..)

If these new inverter supplies use a higher frequency and smaller
toroidal type core, that might open the possibility for easier
mods for ham use. I'd think it would have been featured in one
of the more technical ham magazines by now, though..

Pete


"AS IS" the inverter supplies are not suitable for ham use unless you want
to do some EME work on 2.4Ghz. Probably why you havent seen anything about
them. I was just hoping to learn enough about them to make some power
supplies are are usable must like several people have modified the 60 cycle
transformers for various uses.



Jimmie

"Jimmie D" wrote in message
...
If these new inverter supplies use a higher frequency and smaller
toroidal type core, that might open the possibility for easier
mods for ham use. I'd think it would have been featured in one
of the more technical ham magazines by now, though..

Pete


"AS IS" the inverter supplies are not suitable for ham use unless you want
to do some EME work on 2.4Ghz. Probably why you havent seen anything about
them. snip Jimmie

Why is that? Did you find some specifics on the design that would preclude
something like adding filtering to the output to provide a filtered DC
voltage?

Pete