If you're 7300 user sure You can hear loud noise when TX starts and running. Superb microphones we have now, can catch these noises and make additional shack enviroment "hum" on transmit.
Not to mention about annoying noise in general every time TX starts. Do You feel the same?
Below is my approach and some "amateur shack" tests conducted using low noise engineered NOCTUA fan made in Austria. These fans are "tweaked" at project stage to generate as low noise as possible, keeping the Airflow and RPM on demanded level. This ended up with special air channels, propeller dimensions, as well as anti vibration silicone pads at mounting holes.
Here's NOCTUA NF8-A PWM
Prior to replacement and fan tests let's look on my table with parameters comparison.
Original Icom fan made by Y.S. Tech, and Noctua NF8-A PWM
As we can see there are few major differences, most important for us is Acoustical noise made by fan, and Airflow during operation. Will back to this later, in part II.
Two kind of tests were made. One with "sensor" - ordinary Android phone with sound meter application installed, placed on the rear of TRX, 10cm away from fan, second where "sensor" is lying on the TRX with microphone facing back of the TRX (close to operator position).
Original fan Y.S.TECH FD128025HB-N test:
(notice noise increase after PTT switch - significant increase after PTT click on the noise line)
Position 2 :
NOCTUA NF8-A PWM
Now You can answer yourself, is it worth to spend some additional money replacing noisy 7300 fan and get the silence when operating or stay with your factory fan. Replacing the fan takes 30minutes to complete, just soldering two wires, after removing bottom cover of the TRX.
This is how it looks like after replacing :
Next part will be focused on temperature factor of the mod.