Hi All,
Thanks for the pointer Don.
I looked last night and found (blush) that I was checking the voltage at the
wrong pin. I'm glad I took a step back and came at it fresh without pulling my
hair out. Fortunately that is a trait I've learned from programming as a job.
So, when measuring the right pin, the max voltage I can get is 3.77v. The
voltage at the 8v regulator output is 7.79v and at the regulator input has been
in the range of 12.9-13.3v depending on the battery's charge. I may be within
the range of error for my DMM, but I don't know.
Is the voltage out of the regulator within the expected tolerance?
Is it a problem that I have maxed out the trimmer pot to get 3.7v or is that
expected?
Thanks for your help.
73, Matthew
----- Original Message ----
From: Don Wilhelm <[EMAIL PROTECTED]>
To: Matthew Denson <[EMAIL PROTECTED]>
Cc: elecraft@mailman.qth.net
Sent: Monday, July 30, 2007 4:07:26 PM
Subject: Re: [Elecraft] Problem setting AGV Threshhold
Matthew,
You reading of the schematic is correct - the voltage at U2 pin 5 is the
result of a voltage divider network - nothing less, nothing more. If
you have a problem here, one or more of the resistors involved is wrong,
or the voltage from the 8 volt regulator is not correct.
The RF Gain control is one of those resistors, so be certain it is set
to the full clockwise position.
73,
Don W3FPR
Matthew Denson wrote:
> Hi All,
>
> I am building my K2 and have reached the initial checkout steps before
> building the receiver.
>
> On page 48 of my manual (Rev G if that matters) the instructions say to
> "Adjust R1 for a reading of 3.80...."
>
> On my K2 the way it is right now the range of voltages I get by changing R1
> is 2.1-3.28Vdc. Hmmm?
>
> I looked at the schematic on the way to work today (I'm still there) and it
> doesn't look like there are that many variables here. It is a simple voltage
> divider of the 8v regulated voltage to ground as far as I can see and it
> seems like the max voltage should be 1/2 of 8V when R1 is completely shorted
> out. I haven't checked the 8V source cause I haven't been back home.
>
> Maybe extra useless info - I don't know how the internal volt meter works but
> it is reading out correctly (that is I get the same reading as my DMM where I
> have made identical measurements) so I assume that the 5V regulator is
> working right.
>
> Any thoughts on which points to check? Is my reading of the schematic too
> simplistic?
>
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