Been a ham for 54 Years and engineer professionally. The low power on the new radiuno has me stumped. ? ?I have set up side by side an original bitx40 and the newer radiuno. ?My bitx40 does about 7 ?watts with 12 v. ? ?I am feeding a 1004 Hz sine wave into both units and making measurements into 50 ohm dummy loads. ?All voltages are pretty much in line between the bitx40 and the radiuno. The radiuno only does 1 watt. ? After putting a scope on the radiuno I found some interesting things. ?when transmitting the scope shows that the signal level is very reduded. ?This starts just about at the output of the mic amp Q12 ?and goes up through the trifilar transformer and then on to the input of Q6. ?This level is about 1/3 of what it is in the bitx40. ?I think the low power output is being caused by low drive of the audio signal but I can not seem to locate the issue. ?I have removed the trifilar transforme to make sure there were no shorts.?
There is one change i see between the bitx40 and the radiuno. ? ? Farhan has take out the two diodes and R106 ?and replaced that with a single dual diode (surface mount) ?I removed the dual diode and measured front to back and they are ok.. ? Not much to go wrong in this circuit but I still can not see it. Here is one measurement that I can not quite understand. ? ?At pin 2 of the trifilar transformer T4 ? on the bitx40 (which is working i get resistance measurements of 292k ohm and reversed i get 1.6 Meg ohms. Now on the radiuno i get 14K ohms and reversed i get 81K ohms. ?This is a big difference. I believe it is caused by the new smd dual diode. ? Any ideas?
Tom W5KUB
