SB-610 Experience

[Richard Post]

The negative high voltage is almost a dry circuit.  The 330K resistor
just after the doubler only drops the voltage by 170  (1600 drops to
1430 per schematic) indicating a current draw of just about half a
milliamp.  Has anyone tried replacing the 330K with a smaller one,
say 50K or 100K and also placing a resistor just off the transformer
to limit current in case of a short circuit?  The 600 volt winding
would supply about 3 times the DC current, about 1.5 MA if my math is
close.  A 33K resistor in there would limit transformer current to
about 18 MA in the event of a short circuit while dropping the AC
about 50 volts at 1.5 MA draw in normal operation.

For those who have already lost the 600 V winding, has anyone ever
tried a  little quadrupler off the 215 volt winding?  Would result in
about negative 1200 or so, probably enough to do the job.

Haven't had hands on with SB-610 but faced a similar problem getting
a bit of high negative voltage for a Panadaptor that was missing the
power transformer when I acquired it.

<http://oak.cats.ohiou.edu/~postr/bapix/Panadap.htm>

Also, Heath made a small vectorscope and similar products.  Anyone
know if the transformers in those are usable?  They would have
similar voltage requirements.

Best 73,
Rich

________________________________
Boatanchor Pix - KB8TAD
<http://switch.to/BA>

Museum of Radio and Technology
<http://zip.to/MRT/>



At 12:06 PM -0400 7/31/03, Peter A Markavage wrote:
>Has anyone considered a small low current fuse or a fusible link in
>series with one of the secondary high voltage leads. Given that exact
>replacement power transformers are not readily available and since the
>high voltage secondary winding can be under a lot of stress, due to
>component aging or leaky or possible shorting of the .15 mfd capacitors,
>some means should be provided to protect the HV secondary. I seem to
>recall running across computer monitors and some small portable TV's that
>used fuse links to protect their HV secondaries.
>Pete, WA2CWA
>
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