[Elecraft] KPA100 First tests (p 22)

[Don Wilhelm]

Joe,

It is entirely possible that your ohmmeter is using polarity that is 
different than normal for DMMs.
You *are* using a DMM are you not?  If you are using a VOM or VTVM, stop 
- the voltage used in those meters (ohmmeter function) may be high 
enough to saturate semiconductor junctions and possibly cause damage.

If you do have a DMM, try the U1 pin 2 resistance with reversed leads.

73,
Don W3FPR

On 1/23/2014 11:23 AM, MARY HAYS CARNEY wrote:
> Time to add some extra kick to my K2-10; but, of course, problems arise along the way:
>   
> I find that U1 pin 2 to ground is only 5 kohms rather than > 10K.  I can find no  solder bridges or misplaced components.
>    Resistors R24 and RP1 show the correct values.  Should I suspect that Q10 is shorted?  Other pins on U1 give correct resistances.
>   
> U4, pin 8 shows a resistance of only about 2.8K rather than the expected >10K.  (As directed, the +ve lead of the meter is on pin 8, -ve lead to ground.)  The circuit diagram suggests that this is to be expected since the measurement is made through two forward-biased diodes (D7 and D8) to ground.  Reversing the meter leads gives the expected high value of resistance.
>   
> Voltage tests as indicated on p 26 of the manual give expected voltages with only 300 ma total current (20 ma increase over the K2 alone).
>   
> Joe Carney, KB3FBR
>   		 	   		
> ______________________________________________________________
> 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
>