[AMPS] resistors

[Rich Measures]

>
>
>
>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. 
>>
>>Ä  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..
>
€  You stated that 100K is the suggested max in any literature you have 
seen.  What literature?
>
>>
>>>>>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.
>>>>>
>>>>Ÿ  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. 
>>
>>Ä  What mechanism recharges the capacitor?  
>
>
>An incomplete discharge. Something very easy to do for an inexperienced
>person..
>
€  Bzzzzzt.  You said recharge.
>>
>>>  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.  
>>
>>Ä  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, 

€  In the current catalog, the max. v rating of the 1w, 2w and 3w units 
are all 350v.  This is not logical since the film path in a 3w unit is 
not the same as a 1w unit.  .  Previous catalogs listed the Panasonic3w 
units at 500v max.    


>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.

€  _____ .


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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