You Too Can Build A Junk Box SSB XCVR! 8/31/2016 Results Update 8/31/2016 -- Photos of the Boards Added This is one great radio and following my success at 500 Milli-watts I added the output stage using a 2SC2075 where I am getting about 3 Watts PEP with the device biased for 100 Ma. This in turn can drive my SB-200 to about 45 watts output. With my backyard droopy dipole on 8/30 I worked stations in Arkansas and Texas running 45 watts. So I am pleased. At this point I am torn between putting it in a box or just leaving it "junk style" on the bench. I fear taking it apart may ruin the magic of what has been done so far. Of course if it goes into a box it will get the Juliano Blue treatment. I am really impressed at how well the receiver is working and perhaps some of the additional refinements have helped. The transmitted signal has received excellent reports. In the bi-directional amp stage that started with 2N3904's and then went to a 2N1711 and 2N38
Showing posts from August, 2016
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UHF Germanium PNP Transistor SSB Transceiver Whilst I await some parts for the LDMOS amplifier and Arduino Control system, I began to search my large box of projects that "sorta worked" , worked only once or never worked looking for something I could fix in short spurts of time. Somehow those who possess the "knack" for not having a project work or work properly are always drawn back to the bench in hope of finding the magic pill to bring the "pile of parts" back to life. Mention of Germanium PNP transistors must seem odd today. For some it must seem like a cruel April Fools joke suggested by Bill, N2CQR. Yet for other old timers who really do know about such devices invariably must think N6QW has passed into senility. Yes there really are (or were) Germanium transistors (the CK722 was one of the first) and most early transistors were of the PNP variety. One of the early RF grade Germanium Transistors was the Philco SBT-100. Interestingly
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More Revelations about the LDMOS Control System. Rev 8/19 Added a second video of the three light sequence. My efforts over the past week or so were to further refine and explore the control system functionality. It is has truly been an exercise in "non-linear" thinking which by my definition is not a simple straight line from step A to B to C and so on. Instead it is the need to see that it is A to B & C followed by D and then perhaps and E & F & G. What may seem straight forward and direct often is not that simple based on the complexity of what you want to happen. Above all, the complexity of the control systems lies in the three basic functions of the Arduino control system those being: 1) Pure Control, 2) Supervisory Oversight and 3) Hardware Protection. The Supervisory and Protection aspects frequently drive and override the Control functionality. Overlaying this is the speed at which events must occur to failsafe the very expensive RF device.