[Elecraft] KPA Fan Noise

[Toby Pennington]

Eric,   yesterday Don emailed a number of us off list with the things he did to quieten the fan noise of the KPA500..

I will leave it up to him if he wants to post his modifications or not,  but one of the things he suggested was to entirely isolate the fan itself from all metal sheeting or chassis or the amp. 

He does not utilize metal screws to hold the fan in place now,  but uses other means to hold the fan in place,  thereby eliminating vibrations from the fan from transferring to any other part of the amp.

He also actually balanced the blades of the fan so there was no noise that occured from imbalance of the fan blades.  

He did other things but now says his fan speed never gets over a setting of 1 or 2.  

AS an aside,   I tried to determine at what temperatures each fan speed came on at and am missing one speed.  When I first noticed the fan speed came on it was at 50C;,  then 55C,  60C,  65C, and then 70 C.   That is only 5 speeds so I am missing one speed.  Can you tell me what temperature setting I am missing?  My thinking is I may be skipping one fan speed somehow and that could be making the amp overheat faster. 

Thanks for your help.    Toby  W4CAK