"David Nebenzahl" wrote in message
.com...
On 1/22/2011 7:56 AM Arfa Daily spake thus:

"David Nebenzahl" wrote in message
s.com...

On 1/21/2011 6:02 PM Arfa Daily spake thus:

Actually, I think that it is quite a useful comment, as in my
experience in the electronics service business, many techs -
particularly modern ones - have no understanding that a resistor
has a maximum working voltage rating, and have even laughed at
the very idea when I have suggested it to them, until I have
shown them in a component catalogue. I'm willing to bet that
prior to this exchange, there were more than a few reading what
Michael said, and doing just that ...

Well, I have to admit that it (maximum resistor voltage ratings)
doesn't often occur to me, simply because I don't work with HV. But
the person Mr. Terrell responded to above was certainly aware of
why his resistor got blown to smithereens. Hence my annoyance.

I see that, but some other less experienced people reading the thread,
may well have learnt something from the comment. Still, all sorted now,
and everyone's up to speed on resistor voltage ratings !

Well, point taken.

While we're on the subject, where would one get HV resistors, anyhow? Any
US suppliers?


--

I haven't seen any *very* high voltage resistors for some time now in
catalogues, although I expect if you went looking for them, they are still
around from specialist manufacturers. Most that are readily available here
in the UK are rated at up to 400v for some, rather less for others. If I am
replacing a resistor that is going to have a lot of volts across it - for
instance a bleed or voltage sharing resistor across a high voltage cap in a
tube amplifier - I tend to make one up from two half-value resistors in
series. Likewise, when replacing some anode load resistors in 12AX7 or
whatever stages, as these are often 100k connected to a rail of up to 400v,
with the actual anode voltage at the other end, two or even three hundred
volts lower than that. Two 47k resistors rated at 250v each, and connected
in series, ensure that the replacement is up to the job, long term.

Arfa