The design of the Lowpass filter was found on the internet. It contains 2 inductors and 3 capacitors.
I have build 2 instances of this filter.
However it did not seem right. I doub that the component values are right. So did some simulation. I have used 5spice to. The filter responses looked strange. It has attenuation at 144 MHz. That can not be good.
So I changed the component values. Now it seems to work allright.Nevertheless I will have to check the transmitter using a spectrum analyser.
I get 7-8 watts out using a dummyload. Input power is 12 Watts. This look ok.
fortunately TX was stable whith an antenna connected.
I hope Power suppy can handle the 1.2 Amps that the PA needs. The transformer is rated at 1.2 ampere. I need 200-300 milli Amps for the other parts of the transceiver. So far I have used a separate powersupply for the PA.
The 19 Inch box has room for another powersupply. I have another transformer in the junkbox. so I will be able to solve the problem.
No comments:
Post a Comment