I made some improvements.
- 1) A preamplifier was added. Gain is 12 db. The signals were just to weak on higher bands. It can be turned on and off using a switch on the front panel. I had some space left for it. Now it is getting really crowded inside.
- Filter for band pass tuning was replaced.The old one was too narrow. I bought 15 xtals for 6 MHz. It took some fiddling to get a filter response that was wide enough and was flat enough.
- The pushbuttons that I bought on ebay were awful. They are break when pushed. However when push in to the max, the switch closed again. I have replaced them all by normal on/off switches.
- when switching from TX to RX the AGC attenuates maximal. It takes several seconds before audio is heard again. This was fixed by adding a transistor that empties a capacitor in the AGC circuit when switching to RX.
- 160 meter power output was just 250 milli Watt. I have change a capacitor in the driver. Now I get 3.5 Watts output.
- No more software crashes were seen after improving the software.
