[Elecraft] Elecraft K2 Power Readout Discrepency

[Ron D'Eau Claire]

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!".=20

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.=20

There's more on tweaking the power monitoring circuit at:
http://www.elecraft.com/Apps/RF_Det_application_note.htm

PLUG FOLLOWS:=20

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!=20

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