> Question is -- what is the best value and location for a good B+ glitch
> resistor? It's a bit compact around the plate choke/tube area...I was
> considering putting the resistor in the remote supply in the HV AC lead to
> the rectifier diodes...but then I figured that would not help with the
> charge dump from the filter caps.
Right, it would screw up the regulation by a considerable amount and
not help the surge at all.
> So, I assume that putting the resistor
> right at the HV DC output (after the filter caps) would probably be the
> best spot...is there any problem having this resistor down in the remote
> supply rather than right up in the RF deck area ??
No.
> Question 2 -- Best value/wattage for this resistor ??? and what type ??
> wire wound OK ?? Some smaller values in series to spread voltage drop
> over multiple resistors ?? All helpful comments appreciated !! Thanks!
A few important points often overlooked:
1.) The surge impedance includes the plate choke, wiring, capacitors
ESR, and so on. In many amplifiers, this ESR totals ten or
twenty ohms. Consider this built-in ESR when you add a resistor.
If the ESR is ten ohms, and the amps distributed ESR in the HV loop
through the capacitors is 10 ohms, you cut fault current in half.
If you want to make a big improvement, be sure to add enough
resistance to make a worthwhile difference.
2.) Most resistors have a terminal to terminal voltage rating.
Typical ten watt wire wounds are rated at less than several hundred
volts. It does no good to use protection that fails at an
critical moment. Since the failure is generally an arc from turn to
turn, the resistor can look like a non-resistor.
HV pulse rated resistors are cheap, and available many places. It
makes sense to use the right type and value of part. If you are
going through the bother of installing something to protect 300
dollar tubes, three bucks isn't a lot to spend.
73, Tom W8JI
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