Cooling For GM300

[tsunami_australia]

I'm looking for an option for cooling my Radius mobile radios which sometimes have higher than specced duty cycles. At the moment I have a 90mm computer fan behind one and a 120mm fan behind the other. The issue I have is that these fans run 24/7 and I'd like to change this to 1-2 40mm fans hot glued to the rear of the radios and either run by some 555 timer off the tx but I would much prefer to have some sort of thermal sensor for each radio attached to the heatsink somehow and have it so whilst ever the heatsink is above a set temperature the fans are spinning.

I've tried googling some different pieces about thermal management but I'm not having much luck on this. I'm sure someone has to have done something similar already and I'm hoping to find out what they've used and what they've done to achieve this.

TIA.

[SteveC0625]

I'm looking for an option for cooling my Radius mobile radios which sometimes have higher than specced duty cycles. At the moment I have a 90mm computer fan behind one and a 120mm fan behind the other. The issue I have is that these fans run 24/7 and I'd like to change this to 1-2 40mm fans hot glued to the rear of the radios and either run by some 555 timer off the tx but I would much prefer to have some sort of thermal sensor for each radio attached to the heatsink somehow and have it so whilst ever the heatsink is above a set temperature the fans are spinning.

I've tried googling some different pieces about thermal management but I'm not having much luck on this. I'm sure someone has to have done something similar already and I'm hoping to find out what they've used and what they've done to achieve this.

TIA.

There's all kinds of thermal switches to be purchased over the net. Some are N/O and some are N/C. You just have to search to find one that trips at the desired temp.

My travel trailer has a thermal switch and a standard muffin fan on the propane operated refrigerator's cooling coils. If the temp reaches a predetermined high, the switch closes and engages the fan. When the temp drops off, the switch opens and the fan shuts down. It's all done with automotive 12vdc. IIRC, the replacement thermal switch is just a few dollars.

[tby]

I have used these Single-channel Thermal Relay Control Sensor Module Temperature Switch 12V. (On ebay 251370485494)

[Will]

Look on frozencpu dot com. They offer all types of fans and thermal switches. We use tmp-66 KDS9700 thermal switch 40 C. A stand alone switch.

Akasa Auto Thermal Fan with built in themo control. Works best in exhaust applications as the thermo sensor is in the fan's air path.

The R1225 higher power transmit power chassis used a larger heatsink made from a much heavier material. and will take the GM300 PA board with no changes. I do mill the heatsink as the casting is not flat where the transistors mount. Also use Artic Silver heatsink thermal compound on the transistor mounting. This also applies to the GM300 heatsinks.

I have photos if you need a better look.

[tsunami_australia]

Thanks for the replies folks I'll chase this up over the next week. I guess I'm looking for a no which closes at said temperature to allow the circuit to enable the fan. 40c would be an appropriate temp I guess, anything from 30-45c.

[Will]

I guess I'm looking for a no which closes at said temperature to allow the circuit to enable the fan. 40c would be an appropriate temp I guess, anything from 30-45c.

That would be the tmp-66 KDS9700 thermal switch 40 C. Closes on temp rise.

[tsunami_australia]

Ordered 2 today. Hopefully the fact they are 250AC won't matter much on 12DC.

[Will]

Ordered 2 today. Hopefully the fact they are 250AC won't matter much on 12DC.

No problem, they like 12 volts just fine.....

[tsunami_australia]

Sweet. Our local(ish) electronic components dealer wanted just under $18 per 15v DV thermal switch vs the $5 per for the suggested company. So 2+post still only came out to one without the $12.95 post from the local mob and that's with international shipping.