Doug,
Please read this whole post. If you have questions about any part of
it, please ask.
A Hi Cur message does not mean that the PA transistors are in danger.
All it means is that the current draw is greater than what is set in CAL
CUR.
Set CAL CUR to 3.5 for most operation, and all should be OK. If you
have 'special conditions', like when running on a battery, you might
want to set CAL CUR to a lower value to indicate that the battery
voltage is getting low.
Check your power source voltage at the K2 end - ideally it should be
13.8 or even higher.
What does the voltage have to do with the current draw, you may ask --
The K2 attempts to maintain the power output requested by the Power
knob. Do a little ohms law - if for a power of 10 watts, you need 13.8
volts and 2.5 amps, if your voltage during transmit drops to 12.7 volts,
the current MUST go up to maintain that 10 watts output. The K2
firmware does just that, and if the current increases above the CAL CUR
setting, it will flash the HI CUR message and fold the power back. That
is how the K2 protects the PA transistors.
When operating on batteries with CAL CUR set at 2.5, you can expect a HI
CUR message at 10 watts.
So check your power source voltage in transmit (use the K2 display to
see the internal voltage) and if you have less than 12.7 volts, that is
reason for the Hi CUR message.
You can increase the CAL CUR setting to 3.5 with no harm - in fact, that
is what the setting should be if the KPA100 is installed. CAL CUR and
HI CUR relate only to the base K2, and not to the KPA100 - that is an
indication that a CAL CUR setting of 3.5 is not a problem. When I was
repairing K2s, I always set CAL CUR at 3.5 even if they were only a K2/10.
73,
Don W3FPR
On 9/2/2021 4:56 PM, Douglas Hagerman via Elecraft wrote:
I was out this morning trying some antenna configurations at the park, ten
different setups, one one of them gave me a HI CUR error. It was on 20 meters
with 10 watts and with the current limit set at 2.5 amps, left over from when I
was working on the radio a few days ago. The SWR was 1.2 into a 49 foot wire
using the KAT2 tuner.
Am I correct in understanding that high current in the power amplifier is not
bad in and of itself, as long as it stays below the point where it damages the
transistors? In other words, if the power setting is high (here, 10 watts) then
with a good antenna the PA will see high current just as part of normal
operation? And that the goal is to set the limit high enough (3.5 A) so that
the error doesn’t occur AND the transistors don’t burn out?
Sorry for asking these questions that were probably answered in 2002 or
thereabouts!
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
