[SBE] FW: Question about a Crown exciter and transmitter, over temperature, and spurious signals

[Gary O'Guinn]

Just to think out of the box, if you could isolate the component that is 
overheating you might be able to apply a Peltier Cooling unit to just 
that one device. Then use a small "muffin" fan to remove the heat from 
the hot side of the Peltier junction. If you got really fancy you could 
attach it to a thermostat so it would only operate if the room 
temperature rose to a set point.

Gary O'Guinn
KTUU-TV

Mike Langner wrote:

> Hello everyone !

>  

>  

> I'm about to try to "fix" a problem on a site where an FM transmitter 

> operating at about 1 kW power output and about 1 kW erp may be causing 

> interference to some VHF Public Safety equipment at a remote 

> mountaintop site.

>  

> Access to the site in wintertime is an arduous snowshoe/snowcat trip, 

> so nobody involved in the problem has been there in wintertime when 

> the problem occurs.

>  

> Summertime presents no interference.

>  

> My suspicion is that the FM transmitter building (a typical tiny 

> mountaintop building) overheats in winter from snow pack into the 

> marginally designed airflow/vending, and the equipment overheats.

>  

> The equipment in question is a Crown FM 100 exciter operating at about 

> 60 watts, and a Crown FM2000A transmitter operating at 1050 watts.

>  

> The system employs a Shively 2604-3A bandpass cavity filter in the 

> output.  The radio station owner voluntarily purchased and installed 

> the filter as a goodwill gesture and to attempt to stop any spurious 

> signals from getting to the antenna.

>  

> My sense without going up the mountain (I was there once a number of 

> years ago) that the Crown equipment is overheating, generating 

> spurious signals that may be emitted through the cabinet or by 

> inter-chassis wiring.

>  

> I have gotten reports that the building is "hot" in wintertime.

>  

> Does anyone have any experience with "hot" Crown exciters or 

> transmitters getting "squirrelly?"

>  

> Seems to me that I repaired a 100 watt Crown amplifier some years ago 

> which exhibited exactly this problem.

>  

> Your thoughts?

>  

>  

> Thanks!

>  

> Mike/

>  

> Mike Langner, CPBE 

> 929 Alameda Road NW

> Albuquerque, NM 87114-1901

>  

> (505) 898-3212

>  

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