[Elecraft] Elecraft K2 Power Readout Discrepency

[Robert Boerhorst]

Ron,

Thanks for your quick response and advice. I will measure the output of the
5 V regulator and go from there.

As I said in my earlier message I have lived happily with the situation as
it is for more than a year now, but reading the message from Parker I
thought I have te same experience. I have not opened the K2 since the last
time I adjusted the CW filters with Spectrogram now more than a year ago.
The K2 is the best rig I ever worked with. I try to make at last one or more
CW QRP QSO's with the rig daily with the object to reach QRP DXCC (95
entities sofar).

I am familiar with the site of Sverre Holm, LA3ZA, but forgot to look at it
for existing mod's on K2 power readout.

73/72,
Robert, PA0RBO
K2 # 2406



----- Original Message -----
From: "Ron D'Eau Claire" <rondec@easystreet.com>
To: "'Robert Boerhorst'" <rob.boerhorst@veteranen.nl>;
<elecraft@mailman.qth.net>
Sent: Monday, May 19, 2003 5:56 PM
Subject: RE: [Elecraft] Elecraft K2 Power Readout Discrepency


> If the power indication is uniformly off across the bands, you probably
> don't have a problem with the diode. The usually manifestation of diode
> issues is that the metering accuracy varies a lot with frequency.
>
> There is a voltage divider (R67/68) in the circuit that sets the output
> level to "calibrate" the system. You can change the value of R68, or
replace
> R68 with a small pot, to make the K2 power meter agree with the external
> wattmeter and then, as our friends in England are fond of saying: "Bob's
> your uncle!".
>
> It's very likely that in your case the 5 volt regulator used by the A/D as
a
> reference is slightly "off" the nominal value. The accuracy of the
> calibration is dependent upon that voltage being exactly 5 volts.
>
> There's more on tweaking the power monitoring circuit at:
> http://www.elecraft.com/Apps/RF_Det_application_note.htm
>
> PLUG FOLLOWS:
>
> Looking up the above application note, it occurred to me that a lot of
newer
> folks might not know about the fantastic job Sverre Holm, LA3ZA, has done
> collecting and cataloging the documentation on mods, application notes,
> builder alerts and other general information about the Elecraft rigs. If
you
> haven't done it already, bookmark:
> http://www.qsl.net/la3za/K2/mod.html
>
> It's a great resource!
>
> Ron AC7AC
> K2 # 1289
>
> -----Original Message-----
> Subject: [Elecraft] Elecraft K2 Power Readout Discrepency
>
>
> With reference to the message from Parker, WD9JOL, dated Sunday 18 May
2003,
> 11:21 on the discrepency between the power out indication on the K2
display
> versus power out reading on an external Wattmeter the following:
>
> My K2 #2406, has the same discrepency. The K2 indicated output power is
> always about 2 Watts higher than shown on my WM-2 Wattmeter. It varies a
> little per band, but not very much. The Reflected power is set for 0 and
the
> output at the WM-2 is set at 5 W (max. QRP power out). It has been this
way
> since the first use of my K2 in Feb. 2002. ... I have lived happily with
the
> too high K2 power read-out, but if it can be made better in a simple way,
> for instance by changing D9 for a better diode,  I'm interested.
>
> 72/73,
> Robert, PA0RBO
>