www.webx.dk Start page
MY little Radio Control page
UHF RC system PA stage

see version 2 UHF RC system, we have test flown V2 for over 1yrs now
see version 3 UHF RC system, brand new stuff here
see also booster-in-action, test flight with video googles and long range receiver antenna

Old NMT car phone PA stage, 10mW in 40W out, peak 60W with voltage gain control,
and powerout voltage sense.

Homemade alu plates

Homemade gain controller with 5 power steps

Schematic, the 5 output powerlevels:
+20dBm 100mW (same as input power with attenuator)
+30dBm 1W
+37dBm 5W
+40dBm 10W
+44dBm 25W (to prevent the need of a fan I limited the power to only 25W)
during testing we have seen this PA giving 79W for a few sec, so it is truly a monster

Controller mounted

Output N connector mounted

I was lucky to find a really cool connector

PA power and gain control power on 2 and 2 pins, also note the power sense from pa


My normal TX power is 100mW so I had to mount a 10dB attenuator on the BNC input connector
note the ferite and protection diodes, I will mount a large fuse on the power cords.

Ready for bottom plate.






now fully assembled with double isolator and load

this isolator and load was kindly supplied by my sponsor combilent.com

it is designed for 410-430MHz range, but covers a much wider range in reality, good for me.
insert loss is only 0.15dB calibrated, and return loss both ends 23-30dB really good

isolators are good for many thing, they also perform as a really good band pass filter
so i dont have to worry on harmonics, also I can transmit full power with the worst antenna or even with out if I like,
and still the PA scetion always see a perfect matched load

it is big and heawy, but only used when ultra long range is needed.

-Thomas Scherrer OZ2CPU 2007