uBITX Increasing 28 Mhz output by changing C81 #ubitx-help


When Farhan released the new V4 boards, one of the advertised changes from V3 was a better distribution of output power across the bands,
realized by changing C81 near Q90 to 470pF.

I tried to replicate this change on my V3 board but the net result is about 1W out across all the bands with a supply voltage of just over 12V.
I noticed that in the V4 schematic R83 changed from 10 ohms to 2.2 Ohms so I made that change as well and it made little to no difference.

I also tried adjusting RV1 and it does make a slight difference but there is very little room for adjustment on this pot so the change is insignifcant. 

What am I missing ? 

I reverted back to the original components and I am back to about 5w out on 40m and 1W out on 10m with 12+V supply.


Michael VE3WMB

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