PA Leistungsmodul für 70cm Band, 28-32 Volt / ca. 20 Amp
On Ebay in Germany I found this module,
bought it for 64 Euro
Module as it arrived
When looking at the specifications of the
BLF861A then it was clear that the amplifier was not working as it could
I decided to try and see if I could optimise the amplifier
I tried adding a tuning capacitor on the output and power output
increased to 250 Watt with 17 ampere total current, I replaced this with two
small SMD capacitors of 5,6 pF on each output of the BLF861A so 4 in total
With 5 watt power drive the output power was 250 Watt a gain of 17 dB
I got some questions to further explain what I did so here is a bit more
I added on the input of each transistor a trimmer see the picture
The way I mounted the coax cable:
total amplifier ready for use,
Some lessons from other Hams who made these modifications:
If you remove the housing and do the modification you have big risk that the amplifier starts oscillating.
After modification max drive power needed is about 5 W to get 250 Watt output.
Use a good reliable power meter to measure output.