Well, I went ahead and built the Gilbert cell mixer from the Elmer 101 pages in LTSpice. I’m not sure I understand the biasing that it uses, but it does seem to work. I’ll think about it more later.
Daily Archives: 12/29/2009
Bounced a signal through HO-68
This morning I got another chance at HO-68, the newest Chinese amateur satellite that was operating in FM mode. I wasn’t sure what the problem was: I had the PL tone setup right and the signals seemed strong enough. On this pass, I fought to try to find a slot to transmit, and finally at the end of the pass, confirmed that I was indeed able to get into the bird. I made the following recording of the pass, and you can hear me in the downlink twice near the end of the recording, calling (without response) to VA7VW and W7JPI. The satellite was actually configured to turn off its transponder while it was still high in the sky here (it is on for a pass over Europe, the North Pole, and then down over the states) so I think I was the last person active before it went off.
Elmer 101: Understanding the SW-40+
I was surfing around the web today looking for an LTSpice model for the NE602, and came across the Elmer 101 FAQ, which is basically an explanatory supplement for the Small Wonder Labs SW40. I haven’t read this carefully yet, but it looks awesome, including much discussion of how the various circuits were designed and work, along with hints on how you might simulate them with PSpice (or LTSpice, presumably).