On Fri, Aug 13, 2021 at 02:50 AM, Ashhar Farhan wrote:
The valves, running at 800v or more had a very high output impedance. Typically a few thousand ohms. A single section pi matching circuit often provided enough Q for the harmonics to stay low. Remember the lore about silver air core inductors and the glorious brass variable capacitors?
Hi Ashhar,
Thanks for this very good information. Aw, yes, those tubes were in a different place voltage and, in this case, high impedance wise, making the high Q tank possible. I remember "high Q" was the ultimate goal many hams seemed always trying to reach (and boasting about) in designs of 40+ years ago.
I'd seen some blurbs and mentions about using GaN transistors in RF amplifier designs. Somehow missed that they will need high voltage to operate. That is interesting... With modern switching DC to DC converters that may not be an issue.?
Just those silver plated coils and big brass variable caps may resist miniaturization. But the fun of accidentally drawing an RF arc into your finger could be back.?
Tom, wb6b
