[Elecraft] K2/100 Power on no RX or PA?

[Don Wilhelm]

Gene,

Intermittent problems are usually caused by a bad connection somewhere.
If it is in a connector, usually removing the connector and replacing it 
will wipe away any oxidation interfering with proper contact.

In this case it appears that the MCU is not sensing the KPA100.

I would suggest that you first re-seat the KPA100 ribbon cable (both 
ends) and the KPA100 firmware IC.

If that does not correct it, re-seat the MCU - Control Board U6.

While you have the shield off the KPA100, check the diodes D16 and D17 
to see if they test as good diodes.  They normally show very high 
reverse resistance and near 430 ohms forward resistance.
An alternate quick check on the health of the diodes is to measure the 
resistance to ground from pin 3 and pin 5 of KPA100 U5.  If normal it 
will be about 43k.

73,
Don W3FPR


On 3/26/2017 9:47 AM, Gene N4FZ wrote:
> This has been an intermittent problem. When the rig sits for a week or so,
> Upon powering ON, the RX is muted, the menu setting shows PA _ _ _, and it
> will not transmit but shows a HI REFL message. I have it connected to both a
> dummy load and a known good HF antenna. In the MENU, I can not adjust the PA
> to come ON again. Powering the rig ON/OFF 5 or more times will solve the
> issue. What could be causing this? Thanks Gene