I am looking for a 2500 VCT HV transformer at about 1/5 amp.

It wants to fit into this space: http://schmidling.com/pwsup1.jpg

Please email

JACK K9ACT


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Jack Schmidling wrote:
I am looking for a 2500 VCT HV transformer at about 1/5 amp.

It wants to fit into this space: http://schmidling.com/pwsup1.jpg

If you can be a little bit flexible, and you don't need continuous
duty operation, consider opening up a microwave oven.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:

If you can be a little bit flexible, and you don't need continuous
duty operation, consider opening up a microwave oven.

What do I do after I put in my cup of coffee?

Sorry.... bad joke.

It's for AM on a pair of 813's so think I need to think bigger but...

js


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Jack Schmidling wrote:
Scott Dorsey wrote:

If you can be a little bit flexible, and you don't need continuous
duty operation, consider opening up a microwave oven.

What do I do after I put in my cup of coffee?

Sorry.... bad joke.

It's for AM on a pair of 813's so think I need to think bigger but...

Well, figure input power on a good-sized Amana microwave is around 1000W,
so you're in the ballpark at least. If you can find two microwaves of the
same model you can parallel the transformers. Be sure to cool the things,
though, if you're going to be running any reasonable duty cycle.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 10 Dec 2006 10:39:32 -0500, Scott Dorsey wrote in :
Jack Schmidling wrote:
Scott Dorsey wrote:

If you can be a little bit flexible, and you don't need continuous
duty operation, consider opening up a microwave oven.

What do I do after I put in my cup of coffee?

Sorry.... bad joke.

It's for AM on a pair of 813's so think I need to think bigger but...

Well, figure input power on a good-sized Amana microwave is around 1000W,
so you're in the ballpark at least. If you can find two microwaves of the
same model you can parallel the transformers. Be sure to cool the things,
though, if you're going to be running any reasonable duty cycle.

Note also that you'll need to remove the copper shunt, if one is
present, from the transformer laminations, _and_ that one side of the
HV winding may be grounded to the XFMR frame.

--
Mike Andrews, W5EGO

Tired old sysadmin

Mike Andrews wrote:

Note also that you'll need to remove the copper shunt, if one is
present, from the transformer laminations, _and_ that one side of the
HV winding may be grounded to the XFMR frame.

Never gave any thought to this but the one problem I see is that I need
a center tapped transformer to use with 866's and the microwave ones do
not seem to be.

js



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Mike Andrews wrote:
Note also that you'll need to remove the copper shunt, if one is
present, from the transformer laminations, _and_ that one side of the
HV winding may be grounded to the XFMR frame.

Why should the shunt be removed? I have never seen one on there, but why
should I remove it if I see it?

The HV winding on these is always grounded to the frame, but it's usually
very clear where the ground point is and it's not difficult to lift. I
would be reluctant to do this, though, because I am not sure how well the
interior is insulated.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Jack Schmidling wrote:
Mike Andrews wrote:

Note also that you'll need to remove the copper shunt, if one is
present, from the transformer laminations, _and_ that one side of the
HV winding may be grounded to the XFMR frame.

Never gave any thought to this but the one problem I see is that I need
a center tapped transformer to use with 866's and the microwave ones do
not seem to be.

It is not, no. You can use two out of phase, but that kills your volume
requirements.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:

Mike Andrews wrote:


Note also that you'll need to remove the copper shunt, if one is
present, from the transformer laminations, _and_ that one side of the
HV winding may be grounded to the XFMR frame.



Why should the shunt be removed? I have never seen one on there, but why
should I remove it if I see it?

The HV winding on these is always grounded to the frame, but it's usually
very clear where the ground point is and it's not difficult to lift. I
would be reluctant to do this, though, because I am not sure how well the
interior is insulated.
--scott


With the shunt in place the transformer is more of a constant current
rather than a constant voltage device.
The voltage regulation will be poor. When you remove the shunt then the
primary winding doesn't
have enough turns for the 115 volts.
Good luck with the project

Bill K7NOM

Scott Dorsey wrote:

It is not, no. You can use two out of phase, but that kills your volume
requirements.

Roger but how does one "out of phase" two transformers?

js



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