[Elecraft] K-2 Alignment & Test, part 1 question

[Don Wilhelm]

Larry,

The 8 volt regulator is causing the low max voltage for the AGC 
Threshold.  Just do as you already have and leave it at the max setting 
and all will be fine.

The 7.6 volts you measured at the regulator output is only 0.4 volts 
low, and is well within the regulator spec of 10%.  Until about a year 
ago, most 8 volt regulators were coming in on the high side of 8 volts, 
but recently, then seem to mostly be on the low side.  For those who 
want to fret about it, you will have to find a low dropout regulator 
that is on the high side of its spec, but as I stated, it will not cause 
a problem as-is.

73,
Don W3FPR

Larry Wright wrote:
> I have completed all items of Alignment and Test, Part 1 with one 
> exception - "Setting the AGC Threshold".  Instead of the expected 3.8 
> volts on pin 5 of U2, I could only get 3.6 volts.  The adjustment 
> range of trimmer R1 was 2.5v to 3.6 v.  The 5 volt regulator output is 
> 4.9v.  RF gain control was fully clockwise as called for in the 
> manual.  Any ideas on why it would only go to 3.6 volts and is this 
> critical?  I left it at 3.6v and proceeded with the remaining 
> alignment and test (part 1) procedure without incident.
>  
> Another observation was that the  8 volt regulator was a bit low at 
> 7.6v.    The voltage and current as measured with the K-2 metering 
> circuits were 13.6v and 80 ma.  An external current meter should about 
> 100 ma.
>  
> Any help will be much appreciated.
>  
> Larry
> N4QY
>