I have a site where I am testing two SDRs side by side. One has an AirSpy mini with 1090 filtered pre-amp (Uputronics) powered via the built-in BIAS-T, and the other is the blue FA dongle. Previously the FA dongle would max out around 1200 messages / second while the AirSpy would climb to 15-1600+ with identical antennas. Now that it is warmer (both in the same outdoor enclosure), the FA stick will go 1600+, and the AirSpy is the lower performing unit. Is it possible the equipment is derating due to heat?
I haven’t had any issues with heat affecting my airspy mini. It’s in the loft which gets very hot in the summer. Under similar conditions I would expect the airspy to be easily outperforming the rtl dongle.
Have you tried swapping the antennas over to see the difference remains the same?
How have you got the mini attached to Uputronics? I have mine directly connected - the theory being that as the Uputronics doesn’t produce much heat of its own, its case is acting as a large heatsink for the Airspy. I’ve also added heatsinks to the top and bottom of Airspy:
The setup lives outside in a section of PVC pipe mounted vertically with the Uputronics at the bottom - air is intended to enter from below and exit at the top.
During the recent (Southern Hemisphere) summer temperatures hit 38 Celsius with no overheating issues.
I found the reason the FlightAware stick was seeing a much higher count. During late night testing I had enabled modeac on that unit and forgot it was still enabled.
That’s not an a heatsink. This is a heatsink:
PS: This post was meant as a parody of this.
I am planning to add some heatsinks to the mini soon as well as the chipsets on the SBC running it. I noticed how warm the mini runs even sitting on my desk.
If you put heatsinks on the some circuits, it might affect the functionality of those chips in RF.
The plan isn’t for heatsinks on the chips in the AirSpy – just a similar plan to what you have posted. The Rock64 board running it doesn’t have heatsinks on the processor so that will be getting them.