I wonder if anyone can help me with this. I built one of these: http://qrp-labs.com/ultimate3/u3mods/lfamp.html It's not what I want but it's what I can afford. In all cases, I was driving it with 25
Hello OM N1BUG, For class E @85%eff you would need some more components. - An inductor in the DC between 1u capacitor and the drain / transformer low impedance input, typical >0.5mH at LF! - A 'tunin
There were many replies to my plea for help. I won't reply to all individually but every reply is much appreciated! Thank you all! To respond to a few things: I do not need a linear amp. I spent much
Hi Paul, My answer may be a bit late. It sounds to me like a EMC issue. A RF choke is needed in the supply line. 1 mH may be a good choice. And i would add a 1000 uF electrolytic capacitor with a low
Am 08.11.2017 14:37, schrieb DK7FC: And i would add a 1000 uF electrolytic capacitor with a low internal resistance (the good ones :-) ) near the Drain, in parallel to the 1 uF capacitor. Sorry that
Hi Stefan, Your answer is not late at all. After working very hard on antennas the past days I am just now getting back to the little PA. About RF choke in the supply line: This is something I don't
Am 10.11.2017 19:44, schrieb N1BUG: I see a nice clean sine wave at the other side of the LPF. With a good LPF, the output often looks quite good on a scope, even with massively distorted input signa
Hello Paul, I just had a look at the circuit (http://qrp-labs.com/ultimate3/u3mods/lfamp.html). One end of the output transformer connected is to the +13.8V should be "cold" (no RF). As already menti
OK. I understand the problems with having RF reach the meter and power supply. To be honest I don't fully understand what you are suggesting with a very small coil (few uH at best) and capacitor... O
Hello Rik, Thanks for the good suggestion. I tried it on a battery removed from my lawn mower. I won't be needing the lawn mower for some months! Running it from the battery does not significantly re
So as a final test today I put a 50 uH choke and then a bypass capacitor on the power supply side of it. With 100 uF I (oddly) found 2V pk-pk RF on the power supply. So it is worse with the choke plu
