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A 34Watt 3400 MHz PA using Surplus Ionica units. - Part 2 the combiners
Not only can you use the PA blocks, but the 3 way hybrid combiners attached to the duplexers (see picture on right ) can be modified to work as 2 way combiners / splitters to connect the amplifiers together as per the block diagram. You will need two of these units. Fortunately these are the parts most people throw away.
Firstly remove the lid from the 3 way combiner and separate
the duplexer (right) from it. You will need to desolder the connection
between the combiner output and the duplexer.
Put the duplexer
to one side as it should tune up to make a nice 3400MHz band pass filter.
Now here’s the tricky bit. You can see that the 3 way combiner contains two, 2 in to 1 hybrid combiners. You need to carefully hacksaw or band saw away the second combiner (the one with the long output lead), and the associated part of the box, leaving a single 2 in to one.
This
leaves behind a nice 2 in to one combiner with a bit of its box side
missing just where you need to fit the common port
connector.
You need to cut a piece of the
bit you chopped off to replace it.
Use the piece with the holes ready—drilled in it for the SMA
connector, and fit it on the new combiner, this can be done by drilling
and tapping it M2. If you can’t run to such metalwork, you can probably
make a good flying lead coax connection to the microstrip and leave the
side of the box missing.
Finally to bring the frequency of the hybrid down to 3400MHz from 3600, you need to stick 3 layers of Kapton tape ( PVC tape will probably work) over the hybrid (see orange patch in bottom picture) . You now have one of your 2 to 1 hybrid combiners.
Combiner and Duplexer
Duplexer
This is the bit you chop off
The completed combiner