[Elecraft] KPA500 Problem

[AC6JA at aol.com]

Fred,
There is a known firmware issue which causes the K3 to sometimes "forget"  
to go back to 100W when switching the KPA500 from OPER to STBY.
Mine has the same issue where I need to periodically reset the K3 PWR back  
up to 100W when operating the KPA500 in STBY.  So far the K3 remembers to  
go to the preset PWR output levels when the KPA500 is in OPER.
Elecraft is supposed to address this issue in a future firmware  release.
 
Mike  AC6JA
 
 
 
In a message dated 9/22/2012 4:31:41 P.M. Pacific Daylight Time,  
k6dgw at foothill.net writes:

On  9/22/2012 3:05 PM, Bill K9YEQ wrote:
> Fred,
>
> More than  likely you are changing freqs and the amplifier/K3 are folding
> back  power based on detected antenna complex loading issues. Until the
>  KAT500 becomes available, you don't need 100 watts on any band to get  
500W
> out!  Back off your per band settings and test.   Whatever you are using 
for
> your tuner, I would suspect it is not  matching.

I think I wasn't clear Bill, and unfortunately, it's not the  first time. 
:-)  The KPA500 wants between 25 and 30 watts, depending  on band for 500 
watts out.  The irreproducible "problem" I described  seems to be in the 
dual-power memories in the K3.  The most common  manifestation is:

1.  KPA500 --> STBY, usually because I  punched up a new band on it.

2.  K3 TUNE:  Mine is 5W.   I tune up the antenna coupler [MFJ 989-C], 
SWR=1:1

3.  KPA500  --> OPER, because I pressed the switch

4.  K3 TUNE:  SWR  still 1:1, but now into the KPA500 of course, output 
power around 60W  [still 5W tune power from the K3]

5.  Tap K3 TUNE, now I'm  receiving and ready to TX.  KPA500 is in OPER. 
K3 should have  gone to 25-30W depending on the band.  Start to send, 
KPA500 output  is still around 60W [and the DX calls someone else], and 
when I move the  K3 PWR knob to check the setting, it is still at 5W. 
The only way I've  found to get it back to the 25-30W range is to turn 
the PWR  knob.

This only happens every now and then, more often then than now,  nearly 
all the time it works as expected ... ending TUNE on the K3 sets  the 
power to 25-30W if the KPA500 is in OPER, 100W if it isn't.  If I  had to 
guess [hardly ever a productive troubleshooting technique], it  looks 
like the power memories are fine, the K3 is just missing some signal  to 
tell it to go into normal operate mode with an active  KPA500.

The reverse problem ... running barefoot at 100W and I put the  KPA500 
into OPER [using the front panel switch] because the DX isn't  answering 
me [and I'm going to show these clods in the pile!] and the K3  stays at 
100W [lighting up the 500 :-)] has happened a few times, not  nearly as 
often as the reverse problem described above.

I've tried  re-seating the big cable between the KPA500 and K3 several 
times, once  with a drop of DeOxit into the contacts, with essentially no  
change.

Since I can't make it happen on command, I'm loath to do  much more than 
mention it here, and maybe should stop that.  I sent  my K2 to Don once 
with what I perceived as a clear problem, he spent a lot  of time for 
which I'm sure he did not charge me, and couldn't make it  fail.  It's 
never happened again, in fact I managed NH8S just before  QRT with K2 @ 
5W to my new AlexLoop out on our  deck.

73,

Fred K6DGW
- Northern California Contest Club
-  CU in the 2012 Cal QSO Party 6-7 Oct 2012
-  www.cqp.org

______________________________________________________________
Elecraft  mailing list
Home:  http://mailman.qth.net/mailman/listinfo/elecraft
Help:  http://mailman.qth.net/mmfaq.htm
Post:  mailto:Elecraft at mailman.qth.net

This list hosted by:  http://www.qsl.net
Please help support this email list:  http://www.qsl.net/donate.html