Transmitter Temperatures

Hi Folks,

I'm a little concerned that my transmitter is running over-temperature as it is triggering the alarm on occasion. My question is, what is the expected exc. temperature for these conditions.

My test conditions:

CYBERMAXFM+ SE+ 50W FM transmitter with or without audio load.
Running at 10Watts in to a Bird Thruline (model 43) & Bird 300 watt dummy load.

I have checked that no heatsync screws have come loose in transit.

Here are a few test results:

Ambient temperature = 23 Deg C
Transmitter as-is = 73-75 Deg C
Cover off = 66 Deg C
Cover off with plastic deflector = 56 Deg C
Cover on with deflector = 70 Deg C

The deflector is just a piece of plastic that redirects the fan down onto the TOP of the BLF881. I appreciate that the device will tolerate considerably higher temperatures but I also note from the data sheet that all tests are done with Tj at 25 Deg C and that the devices life expectancy is dramatically shortened if run hot.

The arrangement of the heatsync fins in relation to the fan seem a little unusual so I will next try to create a air reflector to reroute the air along the fins to see if I can improve the cover-on temperature.

Your feedback would be greatly appreciated.

TQ

Hi there,

the temperature meter is not very accurate, think of it of an relative meter more than absolute. It shuts down things if they get too hot so the unit can cool down a little, but I wouldn't use it to predict weather

But if you come up with an idea to cool things better do let us know. Easiest way to email me is to leave message here:
https://www.pcs-electronics.com/livezilla/chat.php?acid=592d0

Or use contact us.

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Marko - PCS Electronics
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