A friend told me a few years ago about the heat issue with dongles. I use the noolectric v4 rtl-sdr and
it got pretty warm. I decided to buy a USB extension cable so I could put the stick on the desk. Then I pulled
a couple of small finned aluminum heatsinks out of the junk box and wrapped some rubber bands on to hold
the assembly together. After 1 hour the stick measured 93 degrees Fahrenheit. Mission accomplished.
The heat sinks are on either large side of the dongle...and I am not using indium or silicone to increase heat
transfer. I can easily extract the dongle so I can use the heat sink on another dongle if I wish.
I used a fluke ir thermometer. Better thermal bonding would work even better. Room is 71 degrees.