Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Mike -
The original resistor is a wirewound, flameproof resistor. It actually
vaporizes in the event of a short, or even a flashover in one of the
final tubes, clearing the short and protecting the power transformer.
There are "real" fuses for this high voltage, but they are hard to find
also, and quite expensive. Collins used one in the KWS-1, I believe the
part number is HVB-1. Its about six inches long.
The one ohm resistor suggested would probably work just fine, if it's
wirewound and flameproof. I believe the SPH resistors are the
recommended replacement for the BWH which is what the original resistor
was. The L-4B runs about 600 mA plate current so the max power
dissipated in the resistor would be 600 mW. I don't recall whether the
original resistor was a one or two watt, I believe two.
73, Garey - K4OAH
St Charles, IL
Mike Bryce wrote:
the reason is not really clear..
but here goes
if there is a fault in one or both of the tubes, or a short circuit
someplace on the +2700 volt line
this resistor acts like a fuse and pops open.
the problem is that nasty 2700 volts!
as the resistor opens up, the voltage will simply jump over the now
carbonized resistor.
fact, it would be more accurate to call it a high voltage fuse instead
of a resistor!
aside from the voltage it has to carry, it must be able to conduct the
necessary current as well.
that's why is a special critter... and very hard to come by.
perhaps I could purchase some from the one company via my heathkit
shop since they won't sell to anyone not in the trade??
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
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Note: No trees were killed in the sending of this message, but a large
number of electrons were terribly inconvenienced
On Nov 6, 2007, at 1:42 PM, Tom Bowman wrote:
Hi,
Where is the resistor being used in the circuit?
Any idea why a 1 Ohm, 5% SPH resistor 66-SPH1R00JLF
<http://www.mouser.com/search/ProductDetail.aspx?R=SPH1R00JLFvirtualkey66200000virtualkey66-SPH1R00JLF>
Mouser, would not work?
73,
tom, WA3REY
On Nov 6, 2007 12:49 PM, MT <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
wrote:
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