How to quiet the IC706?

The IC706 ( ohne alles)    is a great set  but has an annoying fan  that always runs. Now using it again for receiving  137kHz  it becomes a problem if you switch of the IC706 it is a relieve.
I tried to find if something could be done about that noise.
The FAN runs at lower speed during receive.
There is an 47R  in series that is shorted during TX (the schematic says 470Ω  but i doubt that.This R is located at the PA board close to the connector of the FAN. It is a power SMD.
Recently i got an SMD soldering station the AOYUE 968   this great demo is the 962 without the extra 30W soldering tool real nice  3 functions in one  120€  Elektroshop  real heavy device 5kG?  8€ shipping costs.  incredible how they can do it! 
But not to hasty .. first test and measure before changing anything.
Had some exercise with a defective Satellite  converter  real interesting parts that normally would just be wasted.
What about a I2C controlled 2.6GHz synthesiser with just a few parts? and UHF transistors and FETS ...
It failed to run the IC706 with the fan off,  it heats up to much. This IC706 was  designed in the times that power saving was not a big issue. Compared to the K3 this one is like a small vacuum cleaner...
So  i did not got a solution.   Testing a higher R  could be lowering this noise.  Bringing down the idle power consumption has to be done first and second lowering the fan.

To PE4BAS,  Bas 137kHz needs a small filter for the 0.1388  strong digi signal DCF37 and others nearby. So i had to use the 500Hz CW filter  WSPR receives only in CW-reverse  but the WSPR setting need adjustment.  Can this CW-N filter be used in USB mode as well?  is there a mod for that?


PE4BAS, Bas said…
Hello Jaap, there is a mod for the fan as well as use of the CW-N filter in SSB mode. Wrote about it in my blog long time ago. See You can find the fan mod here. This will increase cooling on receive but not while transmitting. I did this mod and noticed the Icom does not warm up as much as it did before. Although the noisy fan does come up when transmitting, but not as fast as it did before except in summertime of course. Good luck !
73, Bas

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