I've discovered that my VPWR voltage is high (4.90 V). I don't see
anything wrong with the RF Detector circuit. The signal on D9 is only 84
mV when measured with the RF Probe. So I pressed forward with signal
tracing. It appears I have an RF signal at the Transmit Mixer (0.274 V)
and Buffer (1.45 V) outputs. But at W6 (Band-Pass Filter output) and T-R
Switch #1 output, I have no measurable signal (0.5 mV). Further, DC
voltages check out on diodes D1 to D7 on the RF Board and all diodes are
oriented correctly on the board. I also noted that the Driver and PA
transistors have correct voltages and seem to switch on keydown.
Tuning the Band-Pass filters had no effect no effect on improving output
power. Power remains at 0.1 to 0.2 watts. I was able to tune L8 and L9
for the 30-metre filter to improve reception on that band to receive
some RTTY, WWV and a CW signal.
During the build, I swapped location of the two 20-metre trimmer
capacitors (C21, C23) with the location for the 10-metre trimmers (C44,
C46). In reversing these, it's possible I damaged one or more of the
trimmers. But, if I did, I don't think this would cause the no power
output problem on any band that I'm experiencing.
Murray VA1CQ
On 6/26/2021 6:33 PM, Don Wilhelm wrote:
Murray,
Not only logical, but the only way to approach Transmit problems.
When you get to jumper W6, know that you can and should adjust the
bandpass filters for maximum RF voltage there.
On a new build, be aware that the most common problems are soldering,
misplaced or incorrect components and diode orientation. If you
suspect diode orientation problems, refer to the Parts Placement
Diagrams in the back of the manual to check them.
Another common problem is inadequately stripped and tinned toroid
leads. You should be able to see a bit of tinned lead on the top of
the board.
73,
Don W3FPR
On 6/26/2021 4:58 PM, VA1CQ wrote:
Don,
A logical suggestion. I already have made the RF Probe and it's ready
to use. I was hoping the cause of no power might be something
simpler. I will start troubleshooting in my next work session.
Murray VA1CQ
On 6/26/2021 5:34 PM, Don Wilhelm wrote:
Murray,
I suggest that you build the RF Probe that was included with the K2
kit. The schematic is shown on page 9 of Appendix E along with the
assembly instructions.
After that, start on Appendix E page 12 - Preparation for
Transmitter Signal Tracing and follow the steps shown there.
73,
Don W3FPR
On 6/26/2021 4:21 PM, VA1CQ wrote:
I am just completing the build of K2 Serial No. 6397. Everything
was going perfectly with all receiver tests and adjustments.
Everything is in spec.
Then I started the transmitter tests. I set the output power
control for 2.0 watts. Beginning on 40 metres, I am supposed to be
able to adjust L1 and L2 to measure 2 watts on the internal power
meter. I measure 0.1 to 0.2 watts. Nothing I adjust or do changes
this. My input voltage is 13.6V with 250 mA on receive and 600 mA
on transmit. I've taken a quick read through the Troubleshooting
section, but I'm wondering if I'm just doing something stupid and
only think I have a problem when I don't. Being new to the K2,
perhaps I'm not setting something correctly.
Any tips for what I should do next?
Murray VA1CQ
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