Exactly the same findings here Ed,
Any digital or prolonged SSB pushed the heat up rapidly and the Silenx fans
were unable to regulate it.
Actually the original fans are incorrectly rated... my tests show that they are
closer to 34CFM using an airflow meter.
I’ve no idea what the dBA actually is on these babies, but it’s LOUD!
That also explains why even genuine Silenx will not be enough at just 18CFM
they are only 50% of the original fans.
It’s also possible that Silenx are not rating their fans correctly, plenty of
gossip on PC forums about this... they appear to achieve their low noise by
just using lower that published CFM... just from some comments I’ve read.
For the heck of it I’ve ordered an audio level meter so I’ll be able to make
some actual readings of audio levels when it arrives, probably next week.
I ended up using ThermaTake DuraMax6 fans myself, these are rated at 30CFM and
32dBA this cut the noise down a fair bit but not as much as I wanted...
So I placed a two 75 Ohm ¼ watt resistor in parallel (giving 37 Ohms) to drop
the RPM a bit more, this took the noise down to an acceptable level for me.
These ¼ watt resistors need to be in open air so that there is some cooling
them as the air is pushed through the Flex, otherwise they get warm (not hot
just warm).
The Flex is now virtually silent during RX and only kicks into action during TX
at an acceptable audio level, it then returns to a low level immediately after
TX which is a good sign.
When my dBA meter arrives I can measure the audio level and CFM of the Duramax6
fans with the resistors, don’t have that info right now.
Regards
Ray
EI3GD
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