Brian,
You may have had a problem with T1, but that is not in the transmit path
for a TUNE operation, so you have another problem to find if I
understood your post correctly - no power output during a TUNE operation.
TUNE uses the same path as CW, and the path for CW through the KSB2 is
short.
The BFO signal enters at P1 pin 12, goes through C42 then through diode
D3 and on to the base of Q3.
In order for that to happen, D3 must be conducting - the TXC signal
applies voltage to the cathode to forward bias D3, so be certain there
is at least 2.5 volts on the cathode.
Q3 must also conduct - again the TXC signal biases the Q3 base in
addition to D3. The 8T signal voltage flows through D5 (you should have
7+ volts on the cathode of D5 and the collector of Q3.
With those conditions present, the BFO signal should go through C39 and
exit at P1 pin 7.
The voltages I mentioned are only valid for CW transmit or a TUNE.
73,
Don W3FPR
On 3/16/2013 8:27 AM, Brian Handy wrote:
Dear Readers,
I am right now working on the KSB2 module. It's built, been installed into my
K2, and I was able to hear a few stations with it. This gave me a false sense
it was working, which is not actually true.
I now find that when I put the K2 into TUNE with this gizmo installed, I don't
make power: set 5W on the dial, and get 0.1 indicated when I hit the TUNE
button. I started going back through the DC measurements in RX mode and have
turned up the following:
U2-5: 6V (should be 0.6)
U4-3: 6V (should be 0.6)
These are the ALC THR voltage, seemingly coming out of U2. I looked up the
specs for U2 and I'm not quite sure what to do with this information.
What does this potentially mean?
Cheers
Brian Handy AE7JW
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