On 11/24/2015 8:17 PM, Walter Underwood wrote:
The measured voltage is what the rig is really seeing, after the
protection.
That *is not the case* I've checked the voltage on the KPA3 and, again,
the Voltage display is approximately 0.2 Volts *lower* than measured at
"12PA" - the output of CB1.
Again, *HOW DOES ONE CALIBRATE THE VOLTAGE DISPLAY?*
CONFIG: ADC REF matches the voltage measured at pin 2 of the ACC jack
with nothing connected to the +12V Out. However, the Voltage display
does not match the voltage at either the APP or +12PA. That the
"meter" is not accurate at *either of the two* most important points
- the two points that have the greatest impact on performance - is not
acceptable.
*HOW DOES ONE CALIBRATE THE VOLTAGE DISPLAY?*
73,
... Joe, W4TV
On 11/24/2015 8:17 PM, Walter Underwood wrote:
The measured voltage is what the rig is really seeing, after the protection. If
you don’t want that, you need to put your own voltmeter outside the rig.
A 0.2V difference isn’t calibration, this is you disagreeing with an Elecraft
design decision.
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
On Nov 24, 2015, at 4:55 PM, Joe Subich, W4TV <[email protected]> wrote:
As I responded to to Mark off list, I know the REF ADC calibration and
had already performed it *before* asking for assistance here. The
voltage display was off by more than 0.5 V prior to performing REF ADC.
The remaining the error is still unacceptably high at more than 0.2 Volts when
a simple DVM has significantly greater accuracy.
I *still* seem to recall a calibration procedure for voltage similar to
that for FP, PA, etc. during the initial assembly and test of this K3.
It seems inconceivable that such a calibration process would not be
present since the "12V" sense point follows at least D6 if not D6, Q2,
RFC40 and R36 which in total would introduce a substantial fraction of
a volt offset from the voltage at the APP and provided to the KPA3.
73,
... Joe, W4TV
On 11/24/2015 6:32 PM, Mark E. Musick wrote:
I sent Joe K3 manual REV D6 from early in 2010.
On page 53 of that manual it has the following description for ADC REF and
how to calibrate it.
ADC REF
Allows calibration of the voltage reference used by the K3 to measure and
display
certain values, such as the rig's supply voltage. (Optional.) First,
disconnect
anything attached to the ACC jack. Next, locate the ADC REF menu entry. It
will
initially show 5.00 volts as the reference voltage. Using a DMM set to DC
volts,
measure the actual voltage at pin 2 of the ACC jack. This must be done while
the
ADC REF parameter is being displayed. (Note: The (-) probe of the DMM
should go to the K3's chassis ground, e.g. at the GROUND lug.) Finally, use
VFO
A to set the ADC REF menu parameter to what you measured at pin 2.
So you need to set ADC REF to the voltage on pin 2 of the ACC jack. NOT what
is at the APP connection on the RF board.
73,
Mark Musick, WB9CIF
-----Original Message-----
From: Elecraft [mailto:[email protected]] On Behalf Of Brian
& Cyndi
Sent: Tuesday, November 24, 2015 11:19 PM
To: [email protected]
Subject: Re: [Elecraft] K3 Voltmeter calibration ...
And the info below is what I found in Fred Cady's book on the K3. There is
no other "calibration" for voltage in that book.
Until Don Wilhelm or Wayne Burdick chimes in, I suspect there may not be
any other adjustment available.
73,
Brian, W6FVI
On 11/24/2015 1:49 PM, Joe Subich, W4TV wrote:
I've already set ADC REF as documented in the manual. The Voltage is
still off. There should be a procedure to set the voltage as there
was when I assembled this K3 (s/n 1450) several years ago.
Unfortunately, I can no longer find it in the current Owner's Manual
or Assembly Manual.
73,
... Joe, W4TV
On 11/24/2015 4:01 PM, Brian & Cyndi wrote:
Joe, if you just want to make the K3's voltmeter match your "known good"
reference meter, you need to adjust the "ADC REF" value.
Go into the CONFIG menu, set Tech mode "On", then go to the "ADC REF"
setting. Note what it is before changing anything, in case this
adjustment affects anything else adversely. Adjust the ADC REF value
to cause the voltmeter display to read the value you want. You will
need to go in and out of the menu display to see the results (kinda
clumsy).
Again, this adjustment may affect other measurements, so an accurate
K3 voltmeter may not be that important after all.
73,
Brian, W6FVI
On 11/24/2015 9:32 AM, Joe Subich, W4TV wrote:
It matters not if there is a series diode. The Voltmeter should be
calibrated to the input power. I remember that being the case when
I assembled my first K3.
73,
... Joe, W4TV
On 11/24/2015 11:02 AM, Michael Blake wrote:
Joe, is there not at least one diode junction or solid state switch
in series with the input power inside the K3?
Michael Blake - K9JRI
On Nov 24, 2015, at 10:06 AM, Joe Subich, W4TV <[email protected]>
wrote:
OK, I'm sure I am overlooking something simple but I can not find
(or remember) how to calibrate the voltage display in the K3.
I had to repair one of my Astron RS-35A power supplies for the
first time in 30 years (one of the diodes shorted) and when I put
it back on line I decided to double check the K3 Volts display
against the actual output of the supply. The K3 is reading about
0.2V less than the supply voltage.
I've been over both the K3 Owner's Manual and the K3 Assembly
Instructions but can't find any reference to calibrating the
voltage display.
73,
... Joe, W4TV
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