Ralph, I was raised with vacuum tubes. My first receiver used three type 76 triodes. In school I learned to design with tubes, plot their characteristics and so forth. I homebrewed a lot of transmitters and receivers using vacuum tubes as Ham and I serviced a lot of vacuum tube gear in my work.
And then after just a couple of years working as an Technical writer (all engineering in those pre-computer days) I found myself looking at schematics of transistors. Now, by then, I had read many books on transistors - all about holes and carriers (in junction devices) - but they still confused me. So, one day, I bought several devices, dug some pots out of my junk box along with a few batteries for power and started bread-boarding transistor circuits. It was only a few hours before the "AHA!" moment that had me watching how the collector or drain current varied with the base current or gate voltages. That was about 1960 and I was hooked on solid state. That was before integrated circuits. Oh, there was some TTL around, but most of the stuff I wrote circuit descriptions for were things like J-K flip-flops made out of junction transistors. I still mess with tubes occasionally. I love watching the filaments come up to temperature and the smell of hot glass. But solid state is something that can be bread-boarded in minutes with no need to wire filaments. Many of my breadboards are no board at all, just a big ball of components wired together in a sort of "rat's nest" of components. That works great for low frequency and audio stuff. As long as you are breathing you are young enough to learn and enjoy new things. Give it a shot! You might discover a world of fun! 73, Ron AC7AC -----Original Message----- On Aug 29, 2013, at 4:15 PM, Ralph Parker wrote: >> If you use Joe's solution where PTT is one input into an AND gate, if >> PTT is not asserted, your relays will not close. All inputs to the >> AND gate must be present for the output to change state. > > I've wanted this 'feature request' since K3 Day 1. > Don's solution sounds like a reasonable work-around. > Unfortunately, I'm transistorially challenged. > Can I build this with a few 12AU7s ? > > Ralph, VE7XF ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
