Curt,
How are you attempting to initiate transmit? If you ae pressing TUNE,
then 20 watts is what should be produced - the KPA100 firmware limits
TUNE to 20 watts. If you need to try at a higher power than that, you
must press TUNE and DISPLAY together.
OTOH, if you are already doing TUNE/DISPLAY, then check the KPA100 LPF
toroids for the correct number of turns - count the nmber of times the
wire passes through the center of the core.
73,
Don W3FPR
Curt Milton wrote:
I did some additional troubleshooting, but maybe there
is nothing unusual in these bias measurements?
Bias Rx Tx
D11 13.7 0.7
D12 0.7 129
D13 13.7 0.2
D14 0.7 129
Q1/2 base 0 0.6
Still puzzled as why rig is limited to around 20w
output. Current draw is proportional to RF power
output, as above 20w setting rig will neither draw
additional current nor output additional power.
--- Curt Milton <[EMAIL PROTECTED]> wrote:
Has anyone experienced this problem, or know if I
should troubleshoot the bias, input, or output
circuitry. All is well with the low power bypass
path, and rig seems to work up to around 25 watts
output.
--- Curt Milton <[EMAIL PROTECTED]> wrote:
Date: Sun, 27 May 2007 12:08:40 -0700 (PDT)
From: Curt Milton <[EMAIL PROTECTED]>
To: elecraft@mailman.qth.net
Subject: [Elecraft] KPA100 Failing to Produce High
Power
All has been well up until now, including setting
the
bias per instructions. Without PA's my bias
current
was 330 mA, so I successfully set it for 730 mA
with
the PA's.
I had adjusted R26 for 5w and got the VSWR sensor
zeroed. During my high power test (into a matched
antenna on a clear channel into a good antenna) my
VSWR is reading 1.2 on the K2 and similar on my
external meter. When I transmit the PA devices do
get
very hot (too hot to touch after about 10 seconds)
but
they quickly cool (maybe around 5 seconds or less)
after transmit ceases.
Here is the behavior i am getting. First column
is
K2
power setting (on 20m), second is what the K2
reads
on
transmit, and third is my meter. My meter is not
state of the art but it is reasonable with my
other
rig.
K2 Setting K2 Indicated Meter
15 15 20
20 20 28
25 25 30
30 23 28
35 22 30
40 22 35
50 23 32
Thinking that maybe R26 was way off, i set the K2
for
40 watts and tried to adjust R26 to read 40 watts
-
no
this got me no where.
I tried to operate on different bands with two
different antennas. Same impact on all bands,
except
it has even lower output on 10m.
Troubleshooting suggestions appreciated!
73, Curt
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