I've posted this on OpenPilot, I though people might like it. It could be a future product upgrade for RMRC to improve the weight of the product.
I'm sure your all know the 1.3Ghz transmitters from RMRC I bought the following one and like it alot
800mW* 1300MHz Transmitter - NEW CUSTOM READYMADERC US VERSION
I was doing some work to replace the loose wire harness that connects my battery and video camera with an old USB cable so I could have the power,audio and video in a single 4 conductor shielded cable. I noticed on the transmitter that the loose wires disappear into the side of the box.
so I opened it up and this is was I saw
Yep its a regular 300mw transmitter box with the output beefed up to 800mw at 14V I guess (well 600mw at 12V which is probably what most of us will use if you are using a 3cell lipo.)
Anyway You'll notice the whole unit weighs 74 grams and the box weighs 53 grams!!! Plus all those shims are not the best way to conduct heat from the smaller transmitter box to the outside case. We can do better than that!!
So why not take a CPU heatsink from my old old, OLD desktop computer which I've been looking for a reason to decommission and chop it up to fit on the actual transmitter box? When that little silver box uses 800mw it gets hot to the touch for sure.
I've been looking for a heatsink that might fit the dimensions for you guys. I found one!!! So after digging and digging I found one the exact size you need 50mmx25mmx10mm. Turns out this is a heatsink designed for a LM2596 power module (what ever that is @#$!!) and will handle 2-3 watts!! NICE! This could handle enough heat coming out of a 1000mw or 1500mw transmitter if needed.
Here is a link to one here: just do a search for LM2596 Heatsink... about $2US.
Anyway I used my good old desk top band saw (with new blade ) and my sanding station on my CPU headsink, here is what I came up with. Again heatsink dimensions are 50mmx25mmx10mm tall. You'll notice I made the base about .125" thick, that's plenty thick to distribute the heat though the fins.
Now the fun part, We need a thermally conductive epoxy to glue the two parts together. I happen to have some Cotronics Duralco 128 Ceramic Filled Epoxy which is crazy expensive. But man it is good and strong!! you can call up Cotronics, number is on the bottle in the photo, you only need 5 grams of mixed epoxy. I think they sell 1 ounce packages. You can get the same effect with some JB weld. I've seen overclocker guys use a dab of thermal grease at the center of a heat sink and then use a tiny about of JBweld around the perimeter to bond the headsink to the part and seal in the thermal grease.
So here is the heatsink glued onto the transmitter. Once I got the heatsink in place and the glue was setting I plugged in an antenna and power and let the transmitter heat up the glue to help cure it.
Here is the final weight not bad!! 42grams. I just took roughly and once of weight out of this thing and you can easily hold it in your hand with the power on, plus once it's in my quad it will get even more cooling.
Here is the final install in the back of my HT-FPV the 1/2" height on the heat sink worked out really well. Anyway I hope this helps!