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

[Andrey Stoev]

Hi Sverre,

You are absolutly right! I totally forgot about the current sensor in 
KPA100 - i havent looked at the schematics for awhile. I think i can even 
use the I SENSE signal which already has swing 0-5V. Using an op-amp buffer 
with high impedance input should not affect the signal and than it is a 
matter of an adjustable voltage divider to get it down to 0-1V (QM-130V). 
Peak-holding feature might be a good ideas since QM-130V samples 10 times 
per sec and its not difficult to add. QM-130V has 9 segments so choosing 
swing 0 to 27A will result in an exact 3A per unit display - should be 
accurate enough to detect current anomalies at high power levels..
Small PCB attached to the back of the front panel should do the trick. Now I 
have to find time to build it :-)

73s

----- Original Message ----- 
From: "Sverre Holm" <svholm2 at broadpark.no>
To: "'Andrey Stoev'" <aestoev at charter.net>
Cc: <elecraft at mailman.qth.net>
Sent: Sunday, May 01, 2005 5:25 AM
Subject: RE: [Elecraft] LCD Voltmeter mod for KPA100/KAT100 in EC2


> -----Original Message-----
> The URL for the meters :
> http://www.marteltesttools.com/products.php?cat=113&action=detail&id=69
>
> QM-100V
> QM-110T
>
> QM-130M or QM-140V might work for an amp-meter. Proper current sensing
> resistor (shunt) will be needed and some other components.
> ---------------
> Nice idea with the KPA1100 metering. The KPA100 already has a current
> sensing resistor in the 12V line: R7 0.005 ohms. At 20A it gives 100 mV, 
> so
> maybe it can be used?
>
> 73
>
> Sverre
> LA3ZA
> http://www.qsl.net/la3za/
>
>