Here's some pics of a cooling mod I did on my HB QMX.? It involved spacing the bottom cover away from the main PCB with small nylon standoff which opens up the sides for airflow.?
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I figured its ugly sweater season so . . .? perhaps my butt-ugly mod will be looked at with kind eyes. :)
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The 'yellow' bits were cut out of 2mm ABS modelers plastic sheet. There is a piece behind the proto board to provide insulation from the case.?
The fan is a 25 x25 x 10mm, 5V mini fan that I found on Amazon. It draws just 28ma and is very, very quiet, both acoustically and electronically.?
The cool air is drawn in right over the PA transistors. ?A 4 pack was about $10 US.?
The USB A connector and proto board were sourced from Adafruit. The USB connectors were cheap. Their 1/4 size proto board is a bit pricey but oh so useful.
The side support legs of the USB connector were bent to fit down across 2 holes each on the proto board and soldered down.
I only soldered in the two power leads of the usual 4 as I obviously did not need to pass data.?
If you look closely at the inside view of the bottom cover you can see that I mounted the fan and proto board to the side of the bottom cover with screws and nuts which provided good mechanical support. The large, yellow cover on the side next to the fan was simply super-glued to the side of the case bottom.
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I power the fan with a separate USB A to 2.5 mm power plug.? If I use the same INIU Power Bank in its USB A output port that I use for providing power to the Q, I found that it was necessary to plug in the fan cable first and then the 12V PD trigger cable on the main USB c output port for the main power intp the Q.? Otherwise, there is often a glitch that drops the power to the Q.?
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Not related to cooling, but you may notice that I replaced the power in jack with a panel mounted 2.5mm power socket that I carefully connected to the main PCB power pads with flexible, 18 AWG, insulated wire runs. No chance of loose connector related power issues.?
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I have measured the temperature of the exhausting air dropping back to the 'receiving condition' temperature occurs with a TX duty cycle of around 25% on WSPR.
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I have also done simulated dummy load runs of FT8 CQ's that last about 6 minutes before WSJT-X stops the CQ'ing because of "No Response" and found that the exhaust side air temperature rises about 4-5 degrees, then drops back to the 'receive condition' temp after about 3-4 minutes.?
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All my testing was on my benchtop at about 23 - 25 degrees ambient. The temperature probe is just a simple thermocouple nichrome wire. Probably not dead accurate, but I was only interested in relative changes.?
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YRMV ....
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73 GREG KI4NVX
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