Tuesday, April 5, 2016

ICOM IC-7600 : NO TX power - repairing, part 2

   I lost RF power on my ICOM IC-7600 a few weeks ago. I ordered BGA-616 MMIC from BY and today I could repaire it. I was also thinking about some protection. MMIC was maybe damaged from the front - too high input signal? I have decided to add two antiparellel diodes. Because of voltage for PIN diode switching I had to add capacitor in series. Connected to R210 - R209 point. I do not know if it could help or not, but it does not have any bad effect on the signal distortion. I measured output signal on the J201 connector. There are harmonic signals from TX one on 14 MHz. Look at the pictures. I also measured output signal spectrum on 14 MHz with 110W output power.

Output spectrum on 20m with 110W of RF power

signals on J201 - BGA616 output, TX on 14 MHz
* add +3dB ... I used 3dB ATT

signals on J201 - BGA616 output, TX on 14 MHz + diodes protection
* add +3dB ... I used 3dB ATT

1 comment:

  1. It is not clear from your photo how the anti-parallel diodes are connected to R209/R210. Where is the other end with the 10nF capacitor connected? Ground? Could you please email me at kb7js@arrl.net ? Thank You. Dave.