Re: [amsat-bb] Thermistor Question, Drake 2880

[Mahlon Haunschild <mahlonhaunschild@xxxxxxxx>]

60 C = 140 F.  That's hot to the touch (hotter than typical household hot water
supply), but not so hot by electronics standards (typical automotive temp. spec.
is -40 C to +55 C).  Most electonic parts are designed for a max. temp
(non-operating) of +85 C.

The real question is whether or not your crystal was cut for ambient temperature
or 60 C.  

Lonnie Movius wrote:
> 
> Hi to the group....sometime ago, I read here on the BB about the
> installation of a Thermistor for controlling temperature for the
> crystal...the particular one was on a Trans System Downconverter...The
> Thermistor is Part number Digi Key KC004P-ND which happens to be available
> in two temp ranges, 50 and 60 degrees.
> 
> I selected the 60 degree device as the part number suggests and the specs
> suggests that the component is a 25 volt device.  We installed the
> Thermistor in a Drake 2880 and much to my surprise with only 12 volts
> applied, this little devil is to HOT to touch.
> 
> My question for the group is...should the device be this hot...at 60
> degrees?  Or should a resistor be applied to drop the voltage even further
> than 12 volts.  Anyone done this mod that can shed some light on the
> subject?  Talk about cooking the crystal!!  The voltage to the unit will
> remain off till I can get some clarification.
> 
> 73's to one and all..
> 
> Lonnie  (NT6B)
> 
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