Temperature measurements on the fan shroud

Mark AJ6CU released a fan shroud for the “tall” Sunil case a short while back. See https://www.thingiverse.com/thing:3790450

He was curious to check out its effectiveness, against  just using the supplied heat sinks or using the heat sinks with a fan.  So here are the results….

Test Setup

  • ubitx v4 with stock PA transistors and the new larger heat sinks being shipped with the case
  • Noctua 1800RPM 80mm 12V fan (Blowing in)
  • Little Volt/Temp gauge that was mounted on the front panel (measurements in Fahrenheit)

Search for: ” DROK Car Voltage Temperature Display” on amazon if you want one!

Unfortunately Mark took the “shroud measurements” on a different day than the”no shroud measurements”.  So focus on the temperature gain over “ambient temperature, for a true comparison.

The first set of tests were for 5 minutes on 40m into a dummy load.
The second set was on FT8 CQ into a dummy load, until the FT8 watchdog timer terminated transmissions.

The Results

No Shroud            Ambient               After 5 Min Xmit       Temp Gain
Fan Off                   81F                          128F                               +47
Fan On                   76F                           94F                                +18

With Shroud       Ambient                After 5 Min Xmit       Temp Gain
Fan Off                   83F                          128F                               +45
Fan On                   81F                           98F                                +17

Operating for 5 minutes into a dummy load suggest that a fan is probably as good as a fan and a shroud.

On FT8 CQ (into Dummy load, until the watchdog kicked TX off):

WITH Shroud     Ambient                 After 5 Min Xmit      Temp Gain
Fan Off                   84F                          105F                               +21
Fan On                   82F                           88F                                +6

Of course the missing measurement is the FT8 CQ with just a Fan. Mark thought of this test *after* he had put everything back together. 🙁 .