When I finish with my homemade SA, I made a list of a few things I'm going to try.
1). Improve ground layout. I plan on taking a Dremel tool and cut a line across the ground copper flow between the PA side and the IF amplifier side. Then I'll find a better common ground point for the two sides. This may reduce the ground loop from the PA feeding into the IF stages.
1a). Experiment to see if using an additional copper clad board, mounted under the uBITX, as a common ground island with various critical points of the circuitry grounded with short straps to the ground island helps at all.
2). Reduce the audio drive level to about where the uBITX currently puts out 1 watt on the lower bands. Then add an additional pre-driver stage before the PA to bring the power back up to around 10 watts. This may make life easier on the IF stages and the mixers.
3). Play more with moving the DC power feed points around.?
4). Rip up the filter relays (Allison's suggested filter fix) and rewire or just go with an external filter.
5). If I go with an external relay switched filler, I may buy a 10W amplifier kit, with a pre-driver, that only requires around 100 mW of drive, and tap into the TX drive chain ahead of the PA on the uBITX board. I'll do this at a point that provides enough gain so I can get 10 watts out with reduced audio drive. I might put both the amplifier and the relay switched filters in the same box. May use the Kees relay board with QRP Labs filters.?
6+) Whatever solutions that have been suggested on this forum that help solve the problems not address by the above list.?
I'm willing to accept the current uBITX may not work on every band, and have other limitations, so I my not do every mod that comes along, if it only improves a band or mode I'm not interested in.?
When a new uBITX revision comes out, I'll likely buy one. As the cost of two uBITX transceivers averaged together (one all bands and one a few bands) is still a pretty good price for two radios I the shack. I do hope any new uBITX will have the same form factor, so it can be dropped into any case people have already built for their current uBITX.?
Tom, wb6b
