[Elecraft] LCD Voltmeter mod for KPA100/KAT100 in EC2

[Andrey Stoev]

Hey guys,



Recently somebody was nice enough to post information about some LCD front 
panel meters he found on internet (Thanks!!!). I thought that such meters 
will be a nice addition to my KPA/KAT in EC2.

The front panel looks empty and it is only occupied by the LED indicators at 
the bottom so there is a plenty of space. I got two meters from Martel 
Electronics - QM-100V  (voltmeter 4 - 25V) and QM-110T (thermometer with 
internal and external sensors, Fahrenheit or Celsius). The voltmeter shows 
the voltage of the main supply and the thermometer shows the temperature of 
the heatsink. The LCD meters are very nice and quick to install (just a 5mm 
hole is needed). They are pretty accurate too - dead on with my recently 
calibrated Fluke. Both meters can be calibrated if needed. The thermometer 
can show the external temperature from a sensor which I installed on the 
heatsink or the internal temperature from a build-in sensor. Both sensors 
can be calibrated if needed (small adjustment screws on the back of the 
meter). I left also space for future addition of an amp-meter, but it will 
require pretty big shunt, which I might install in a separate box outside of 
the EC2. I used different computer connectors (from an old motherboard) so 
everything can be plugged or unplugged easy should I decide to move the 
KPA100 into my K2. There is also a jumper on the back of the front panel to 
switch the thermometer between F and C and EXT/INT sensor).

The voltmeter is also very useful with an adjustable power supply to get the 
exact voltage for charging the SLA battery in K2

Here are some pictures - (sorry, didn't have time to write a HTML).

http://pages.cthome.net/itv/KPA100_LCD1.jpg
http://pages.cthome.net/itv/KPA100_LCD2.jpg
http://pages.cthome.net/itv/KPA100_LCD4.jpg
http://pages.cthome.net/itv/KPA100_LCD5.jpg

73s
Andrey E. Stoev
KB1FZA