[Elecraft] KPA-100 under test

[Phil Wheeler]

Bob,

As a first step, I suggest you check your temp calib.  Pre-cal, mine was 
way high so the fan would not have come on.

I believe fan control is totally on the KPA100 (done by the PIC on the 
PA PCB); so that will narrow down your troubleshooting a bit.

I don't have the manual in front of me, but I would check the voltage 
and resistance readings -- after verifying that the tCAL is correct.

73, Phil


Bob Henderson wrote:

>Hi
>
>I was one of the lucky ones who got to bring back a KPA-100 kit from Dayton.
>The kit is assembled and currently under test.  However, I have hit a snag
>and would appreciate a bit of help.
>
>Testing so far has progressed to Page 46 - Fan Test routine.
>
>The fan does not operate with fan mode set to either FAN LoHi or FAN Hi.
>The fan itself is ok as it operates briefly when the K2 is powered up.
>Looking at the cct diagram on page 62 it is apparent that U2 pin 11 (/out 7)
>should be low to drive the fan at low speed and U2 pin 12 (/out 6) should be
>low to drive it at full speed.  These signals are both unconditionally high
>on my KPA-100.  Outputs RC7 & RC6 from U1 are required to go high to operate
>the fan at low/high speed.  These outputs are both unconditionally low.  U1
>& U2 are otherwise operational as my low pass filter switching is operating
>correctly.  My fault finding has ground to a halt at this point as I don't
>know what input is  required at U1 to turn the fan on.
>
>Can someone point me in the right direction please?
>
>Many thanks.
>
>Bob 5B4AGN
>
>
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