[Elecraft] K2 KPA100 fan replacement?

[Dr John H Farmer]

Thanks Don. I appreciate the tips. The power and ambient temp calibrations check out OK. I'll try changing the fan setting and see what that does.  I work only CW and once the rig gets up to the temperature threshold, after an over or two, the fan stays pretty busy thereafter. Leaving the fan on low between transmissions may do the trick. 

Cheers,
John
VK7JB



> On 23 Aug 2014, at 23:48, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> 
> John,
> 
> That is not normal.  You might want to check a couple things.
> First, connect an external wattmeter and monitor the actual output - set the power control at 50 watts and see how much power you actually have on CW keydown.
> If it is much higher (greater than 100 watts), you have a problem with the KPA100 wattmeter.
> Continued operation with that condition present will cause your base K2 PA transistors to be stressed and will fail sometime soon.  Even if you operate with the power knob set below 11 watts, the base K2 PA will still be stressed because the base PA is putting out the maximum power that it can develop - often exceeding 18 watts.
> 
> Secondly, check the menu setting for CAL TPA - turn power off and wait at least 1/2 hour to allow things to cool to ambient.  Then power on and check the setting of CAL TPA - adjust to the ambient temperature in degC if necessary.
> 
> If you are doing CW (or data modes) with a high transmit to receive ratio, such as during a hot and heavy contest, you can set the fan to LO-HI so it will run at low speed all the time and keep things cooler - that means the times it switches to high speed will be reduced.
> 
> In normal mode, the fan does not run until the CAL TPA temperature (and the heatsink if CAL TPA is properly calibrated) reaches 40 degC and will turn off when the temperature drops to 36 degC.
> 
> 73,
> Don W3FPR
> 
>> On 8/23/2014 7:31 AM, John Farmer wrote:
>> it's more noticeable if you have well preserved high frequency auditory
>> acuity :).  I use my K2/100 for QRP only, because if I work CW at 20W or
>> more, the fan runs pretty much continuously on Tx.
>