Fwd: [GreenKeys] final question on ST-6...

[Don Robert House]

> Hub pots by Western Electric are sometimes available from surplus  
> sources.  I purchased a couple large rheostats from MOUSER about 10  
> years ago, not sure if they still sell them.  We also used similar  
> pots to adjust sealing current on dry circuits back in the 60s and  
> 70s but that is another story.  (Center tapped transformers with a  
> phantom circuit of 20 ma.)
>
> Don
> K9TTY
> Bell System retired
>
>
> On 20 Jul 2005, at 10:43 AM, valerie zeiser wrote:
>
>
>> Hi Eugene;
>>
>> Mine got so hot that it died.
>>
>> I wound up replacing it with a ceramic wirewound resistor
>> that has is tapped.
>>
>> 73,
>> W6ESE - tony
>> NNNNZCZC
>>
>> Eugene Hertz wrote:
>>
>>
>>> Ok...
>>> The rheostat on the back of the ST-6 that controls the loop  
>>> current...
>>> 1. It gets VERY hot. REALLY hot! Is this normal? Is there any way  
>>> I could reduce the heat?
>>> 2. Seems like I can get the loop current to 60ma at the lowest  
>>> but I can raise it to higher (not much) probably to compensate  
>>> for more devices on the loop..Question is, i would imagine my  
>>> 28KSR could probably work off lower voltage and/or current, no?  
>>> Is there some way I could reduce the power consumed by the  
>>> rheostat, perhaps by reducing the current through it or voltage  
>>> across it? I recall some folks talking about running a loop on  
>>> 80v instead of 100+v.
>>> thanks
>>> Eugene
>>>
>>>
>>
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>>
>
>