I used a transformer almost identical to this one in my GS-35B tube
tester <http://tester.gs35b.com>.
It has the welds nicely done connecting all the lams together. Even
after driving the shunts out the transformer is quite lossy. Even with
no load it gets quite warm when you apply primary voltage. I did drive
the magnetic shunts out. They were also paper wrapped and were fairly
easy to drive out.
This transformer had one end of the secondary soldered to a lug that was
under a screw driven straight into a hole in the lams. I took that
connection loose, slipped a short length of Teflon tube over the loose
wire and then soldered it to a solder lug that I put under the original
screw. It put out 2200 VAC no load and with a full wave bridge produced
3000 VDC with 56uF capacitance. Unfortunately, the voltage dropped
quiet a lot under load. With 450 mA load, the output HV will drop to
about 2150 VDC. Not a big deal for what I'm doing but not so good for
an amp.
73, Tony W4ZT
wc6w@juno.com wrote:
> Hi Will,
> This one has four 1/8" wide welds down the opposing sides. And yes, it
> has the shunts but, they are encased in transformer paper so, I'd guess that
> they could be easily driven out without disturbing anything else. No screws
> what so ever. The lams are even welded to the mounting frame in four spots.
> The "cold" end of the secondary was soldered to a lug which was riveted to
> the lams -- I necessarily disconnected that wire for the hi-pot check.
>
> It looks like it's wound at about 1 turn per volt. As the core wouldn't
> practically dissassmble, the only easy rewind would be for a filament
> transformer. The secondary could be sliced out by a careful guy and rewound
> with a bundle of large wires in parallel making a KW filament transformer...
> for say a 4CX5000/10000? Or twenty 813's? :-)
>
> 73 & Good afternoon,
> Marv WC6W
>
> **********************************
>
>
> -- "Will Matney" <craxd1@verizon.net> wrote:
> Marv,
>
> Did you check to see if one of the windings was connected to the core, and if
> the core had a shunt in it? That is what most have that I've seen. Another
> thing that really ticks me about their manufacture, and a few other
> transformers too, is they weld the lams together. They put a weld right down
> one side of the lams, front to back, one bead about 1/4" wide. That makes
> them a bit*h to use for a rewind. A person with a mill, or be good with a
> disc grinder can remove the weld. Also, the shunt needs to be driven out with
> a hammer. This is really good though as it gives you more vertical window
> area for a new coil. What gets me though is why weld them and still use
> screws to hold the lams together?
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR ***********
>
> On 3/12/06 at 11:57 PM wc6w@juno.com wrote:
>
>> QST
>> Yesterday, I acquired a 2004 vintage Sharp microwave oven, from the
>> "alley exchange", which was light (weightwise) enough that I thought it
>> might contain a switching power supply.
>>
>> Upon examining the unit, I found that the incredible lightness was due
>> to its construction with frame metal of soda can thickness, and that it
>> contained a conventional transformer manufactured by one Digital Power
>> Communications Co, Ltd.
>>
>> There was an article in QEX about 10 years ago that discussed the use of
>> these microwave oven transformers in plate power supplies. It advised
>> against using them in a conventional full wave bridge but, rather used
>> them in an unorthodox half wave connection.
>>
>> Examining the transformer at hand, it appeared that the insulation was
>> uniform over the full length of the secondary.
>>
>> I disconnected the "low side" secondary lead from the frame and
>> hi-potted the secondary (also the primary just for science...) up to 4KV,
>> referenced to the frame, with zero leakage.
>>
>> This suggests that one of these transformers might be employed in a
>> "normal" connection for a low voltage (2500V) KW input amplifier. Or a
>> pair of identical units in parallel for a 2KW input amp.
>>
>> Caution, this suggestion MAY NOT hold true for other makers of this
>> style of transformer.
>>
>> 73 & Good afternoon,
>> Marv WC6W
>>
>>
>> P.S. -- The magnets from the magnetron assembly make great refrigerator
>> magnets!
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|