After a few qsos on my newly built Bayou Jumper, it suddenly stopped putting out power:
| Crystal (kHz) | RF Out (mW) |
| 7030 | 260 |
| 7122 | 25 |
I forgot to disconnect the antenna one dry winter night, so there might be an ESD issue.
All voltage measurements were made as recommended in the construction manual, and all are normal. Of particular interest are measurements in the transmit chain:
Q4 drain: 13.5 V
Q5 gate: 3.34 V, showing proper bias to oscillator FET.
Q5 drain: 13.6 V
Q6 gate: 13.8 V
A nearby receiver picks up the oscillator (Q5). I made some additional measurements:
1. Below, I hooked scope probe to PA FET gate, receive mode, no crystal, while keying the letter C.
2. Next, with the probe still at PA FET gate inreceive mode, I inserted a crystal and again keyed a C.
3. Here, I'm again keying a C as above, but with the rig in transmit mode.
4. Finally, I measure RF output from my dummy load test point, once again keying a C. Based on my dummy load design, power out is (V**2 + 0.25)/25 = 0.26 W.
5. This capture shows drain-to-source voltage of the PA FET.
Everything seems to look good right up to the PA FET. Its output runs through a 3rd order Cauer low pass filter and then to the antenna.
6. Out of curiosity, I ran sweeps on equipment at work, Keysight N5182B VSG and N9040B UXA signal analyzer.
This one runs from 5 MHz to 25 MHz.
And this is from 6 MHz to 8 MHz.
