G4BAO.COM

Microwave Amateur Radio Station, Waterbeach. 8km North Of Cambridge JO02cg

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A 34Watt 3400 MHz PA using Surplus Ionica units. - Part 4 Connecting up the RF modules

The RF modules, two combiners, four isolators and two PAs should be connected up using high quality semi rigid SMA leads. These are available surplus via EBay and  other sources.


It is vitally important that the leads between the input combiner/isolators and the PA are exactly the same length to maintain the best phase relationship.

The same applies to the leads between the PA outputs/isolators and the combiner.
This means that you might have to wind them in to funny shapes, but don’t worry how they look (see my photos of the completed PA.) Also note the way that the outputs A and B of the input combiner connects to the A and B amplifiers then to the B and A ports of the output combiner.  

Heatsinking

The amplifiers need some serious heat sinking, as the whole unit takes 3.2 Amps at 48V or 154 Watts for 34 Watts out. I probably overdid the heat sinking and fitted 3 small fans as well, but my unit barely gets warm.

Some test at 3400MHz

Hybrid combiners

Return Loss

unit 1

unit 2

Insertion Loss

unit 1

unit 2

Input 27dB 26 dB Input to port A 3.3dB 3.3dB
Port A 33dB 25dB Input to port B 3.2dB 3.2dB
Port B 29dB 28dB A to B 25dB

22dB

B to A 22dB 22dB

 

 

 

 

 

 

 

 

Output Power for 2mW in to combiner:

PA1 19Watts,  PA2 19Watts

Combined Output 34 Watts 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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