I sent the below a couple days ago and just found it bounced. No reason was
give. I've reverified the email address and am trying again.
Hi,
I have no transmit SSB audio on my K2. CW works fine. From voltage
readings on the KSB2 looks like the problem is in the area of U2 - MAX522,
Q1 - PN2222A, U1 - 16F872 and U3 - SSM2165. I replaced Q1 with a 2N2222A,
almost the same specs, and it did not help. Over the last 2-3 months I've
had to turn mic gain and compression to full to get any transmit audio out.
Now there is none. I'm using the Elecraft/Heil MD2 microphone.
The out of nominal (+ & - 10-15%) voltages are as follows. I'm using a
Fluke 8600A multimeter. Only transmit voltages are listed below.
U1-10 sb 3.1 is 2.6 (~15%)
U1-16 sb 5.4 is 3.1 (~30%)
U1-17 sb 5.6 is 4.2 (~40%)
U1-28 sb 2.4 is 5.4 (~220%)
U2-1 sb 5.6 is 4.2 (~25%)
U2-5 sb 0.6 is 1.6 (~280%)
U2-8 sb 5.4 is 3.1 (~90%)
U-3 sb 0.8-1.2 is 0.0 (~?????%)
The discrepancy on U3 appears to be a function of the setting of the audio
compressor. But, could be otherwise.
The radio is about 15 months old and I'm the original owner. I've been
solder certified by the Air Force and NASA and inspected medical
subassemblies for several years so there is a possibility I know my way
around soldering. Just the same I've reflowed all joints and reverified all
components on the KSB2. I've also rechecked all menu setting and all are
fine. I'm using a gel cell battery rated at 8AH for power. It is reading
12.6 volts by the K2 meter obtained by tapping display. The battery will
deliver several amps with only 0.2 VDC drop in voltage.
Any thoughts helps or other ideas would be appreciated.
Thanks,
Jim, AB0UK
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