Posted by
ANDY DURBIN on
Apr 07, 2019; 6:11pm
URL: http://elecraft.85.s1.nabble.com/KPA500-Clicks-Pops-tp7645665p7650696.html
This will only be of interest to a few KPA500 owners - those who don't think loud clicks/ticks/pops are acceptable.
In the message below I reported that I had lost interest in my investigation because the click/ticks had stopped. That message is dated October 2018. Late March the ticks came back and now, early April, they are back to the annoying level that I experienced in 2018. What's different? Room temperature and consequently the powered on but not transmitting temperature of the KPA500 is much lower in the winter months.
Although I lost interest in the investigation I continued to record PA temperature, heat sink temperature, and Z bracket temperature for every transmission I made. That's a lot of data but differences between summer and winter operating conditions may be interesting. I plan to pick a few mid winter samples to compare with a few peak summer samples.
Has anyone else who is annoyed by KPA500 click/ticks noticed any correlation with room temperature?
73,
Andy, k3wyc
________________________________
From: ANDY DURBIN
Sent: Tuesday, October 16, 2018 6:52 AM
To:
[hidden email]
Subject: KPA500 Clicks & Pops
I found this quite annoying too. My approach was to try to understand how the Z bracket temperature varied relative to the heat sink temperature. I placed a thermistor on the front end of the Z bracket and another on the heat sink fin closest to the Z bracket. I logged the standard PA temperature and these additional thermistor temperatures for every transmission I made (still do). I established baseline temperature characteristics and planned to use this data to see if any mods I made changed the characteristics.
Surprise! - When I though I had enough data to move on to the next step in the investigation it stopped clicking.
Adding the thermistors only required removal of the front panel and the Z bracket screws were no touched. It continued to click after the thermistors were added and then stopped a few weeks later.
The data show the rapid change in temperature is at the PA sensor only. The heat sink and Z bracket change much more slowly and never have a large temperature difference. Their temperatures do cross over though.
One problem with temperature logging is that I had no data, except for my test notes , on the clicks themselves. I had planned to added some inexpensive sound detection modules and add this data to the logger. That's on hold until the clicks come back.
It's really nice not to have the amp click continuously on every FT8 transmission. I wish I knew what fixed it.
73,
Andy k3wyc
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