On Sun, 21 Feb 1999 08:22:49 -0800 Rich Measures <measures@vc.net>
writes:
>Carl said:
>>
>>Which is why 100K is the suggested max in any literature I have seen
>for
>bleeders.
>
>? References, please. . In a typical 8171 anode-supply, a 100k-ohm
>bleeder would dissipate 810 watts.
I suggest you read the original post which had nothing to do with your CB
tube. Neither was a single 100K bleeder mentioned in my reply since the
160W dissipation is too close for comfort in a 200W resistor, which could
lead to premature failure..
>
>>>>>If I wanted a Reliable bleeder for a 4kV C-filter supply, I would
>>>>>series up 8 to 10 Matsushita/Panasonic 100k-ohm, 3w MOF resistors
>on apiece of
>>>>>perfboard and be done with it.
>>>>
>>>>Absolute YUK ! 800K to 1M bleders..no way Jose.
>>>>
>>>Ä What is to be gained by using a 200k-ohm bleeder on a C-filter,
>Carl?
>>
>>Quicker HV bleed down time, less chance of a recharge.
>
>? What mechanism recharges the capacitor?
An incomplete discharge. Something very easy to do for an inexperienced
person..
>
>> All my concerns are safety related and for others not well versed
>in PS
>issues.
>>
>>A string of 3W does not offer much of a voltage breakdown safety
>margin.
>>Matsushita not a common distributor item and similar wattage
>Panasonic,
>>etc are only 350V.
>
>? The manufacturer's (Panasonic/Matsushita) rating at 70 deg. C
>ambientis 500v or 3w . For a 100k-ohm unit, the realizable
>dissipation is 2.5w
>at 500v. .
Lets see, what supply are you working with at this moment? The original
post or an 8171 ? You drift around too much trying to make a point that
suits the instant.
BTW, the DigiKey catalog rates the Panasonic/Matsushita 3W at 350V, which
would put a string of 10 over the ratings in a 4KV supply and would be
insanity at 7500V.
Of course, someone recommending an 8171/4CX10000D on the ham bands ( at
least in the USA) is not exactly all there anyway.
Cheers Carl KM1H
.
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>
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