[Elecraft] K2 Glitch on Field Day

[Don Wilhelm]

Larry,

In the past, I have seen several reports of the erroneous PA HOT message 
behavior - it seems to me that it typically happens during a portable 
operating situation - perhaps caused by some mysterious power glitch or 
something like that.  I really don't know the reason behind this loss of 
the setting.

An additional thought is that it may be caused by operating the KPA100 
with strong direct sunlight beaming onto the KPA100 heatsink - the black 
surface will absorb heat (just the same way as it dissipates it) and 
could cause the heatsink to actually overheat from the sunlight.  The 
physics of a 'black body radiator' are what is involved here - it will 
absorb heat just as easily as it radiates heat.

In any case, what has happened is that the menu entry for 'CAL tPA' may 
been lost (it usually goes to 255).  The solution is to re-enter the 
proper value for that menu item.  The 'real' setting is the actual 
temperature (in degrees C) of the PA transistor case (or the heat sink 
next to the PA transistors) - so if you have a good temperature 
indicating meter, you can set it no matter what the temperature may be.

For those folks without such a temperature meter, the easiest way is to 
let the K2/100 acclimate to the ambient temperature (idle for a couple 
hours) then look at a normal thermometer and read the temperature 
(convert to deg. C if the reading is in deg. F) and enter that value 
into the CAL tPA menu parameter.

73,
Don W3FPR

Wolfgang, Larry, WR1B wrote:
> I've seen a couple of posts about folks having some interesting
> "problems" with their K2s on Field Day. I also had an "event," and
> wonder if anyone else has seen this problem before.
> 
> After operating most of Saturday afternoon, I turned off my K2/100
> around 6 to break for supper. Since my wife had invited her brothers and
> sisters for a picnic, it was around 8 when I turned my radio on again.
> When I transmitted to answer a CQ FD, I saw the display show "PA HOT"
> and no apparent output power. I cycled the radio off and on again, but
> got the same message when I tried to transmit. The correct antenna input
> was selected, but the KAT100 wouldn't tune. When I pressed the Tune
> button it just displayed 20 and 1:1. I tried both CW and SSB with the
> same result. I tried switching from 20 m to 40 m with the same result. I
> turned off the radio again and went to visit with my cousin and her
> husband for another hour or so. When I came back, I even tried
> connecting my ac power supply to see if the battery voltage was dropping
> too low for some reason. The PA HOT message came on each time I tried to
> transmit. Finally I tried reducing power to below 10 W. Now the tuner
> would work, and I could transmit, but going above 10 W gave the PA HOT
> message again. I finally brought the radio and tuner inside for the
> night and gave up.