[AMPS] Re: resistance

[km1h @ juno.com]

On Tue, 25 Nov 1997 12:09:47 -0500 k4auw@juno.com writes:
>Hello all,
>
>Wonder if anyone has ever acurately measured a reistor for a parasetic 
>supressor before assembly, soldered it to the PS inductor, then 
>un-soldered and re-measured the value?  I would be interested in the 
>value change for various resistor compositions from the heat of the 
>solder de-solder process if proper heat sinking was done.
>
>73....Ron

Done it many times while trying new ideas...results...no change.
Of course that is with a 140W gun, not a blowtorch. 


73  Carl   KM1H


>On Tue, 25 Nov 1997 08:33:28 +0008 "George T. Daughters" 
><gdaught6@pobox2.stanford.edu> writes:
>>
>>hi all,
>>
>>rich wrote...
>>
>>> If your amplifier arced mysteriously, it might be interesting to 
>>measure 
>>> the resistance of the VHF parasitic suppressor resistor.  
>>
>>it is perhaps important to note that an increase in the resistance of 
>
>>a composition resistor (or a film resistor, too) can increase when 
>>the resistor gets too hot.  (rich has said this, too.)  it doesn't 
>>have to be so hot that it bakes the color bands to new colors.  the 
>>point i want to convey is that it doesn't *have* to be a parasitic 
>>oscillation that causes this change.  i've seen resistors in dc power 
>
>>supplies increase by a factor of 3 or 4 by chronic overheating, but 
>no 
>>
>>smoke was emitted.
>>
>>73,
>>George T. Daughters, K6GT
>>
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