LB3HC's hightech blog

Amateur radio, RF design, electronics, uC, software, Arduino, AVR, Antennas


Archive for 'Linear amplifiers'

A MIL-SPEC roller inductor for QRO operation

I recently got hold of a motorized roller inductor that is made PROPERLY. This is a MIL-SPEC unit that has been on stock for many years. It features a silver foil that is rolled on to a ceramic former, pretension, a shortcut cylinder that prevents eddy currents and arcing on the unused coil section under […]


Very big QRO rolling inductor

I just got myself a new roller inductor. This one is designed on the principle of a silver foil that is rolled away from and onto a ceramic form with guides for the silver form. The ceramic coil forms the coil. There is a large shorting cylinder that the unused silver foil is rolled onto. […]


PL519 HF linear amps by PA0FRI and EA6AFJ

PA0FRI and EA6AFJ has made some cool low power HF tube amps with the old and thrusty PL519. Here is a picture taken by EA6AFJ. This is actually a nice amplifier that should be quite easy to build for the experienced engineer and experimenter. The benefit of using lower anode voltages is that the tank […]