I have a certain suspicion... I found one more person who described their
experiences (it wad also, "put it together , got 70W, no tuning etc
However , that person drew a schematic of their amp and they had an
attenuator in the front. I don't have that. My pcb has pads but no markings
what to put there so I thought it is optional. Also I didn't see it
populated.
I wonder perhaps that attenuator is the answer? Perhaps the input is never
meant to match 50 ohms fully, but that's not a problem because the device
that sends the signal sees the attenuator. This is something I saw in a
tube amp once.
Now, another piece of info is "how" I sent the 1,2.5 and 5W to the amp. My
function generator tops out at 7dBm (and I did get +18dBm from the amp).
But to send 1W and more I used a little baofeng set to min/medium/max power.
I suspect perhaps the baofeng saw the horrible swr and limited the power to
1W. This would explain why I got roughly the same 20W of output on all 3
power settings.
So the key question now is... Are we supposed to make a close to perfect
match on ldmos inputs? Or just add an attenuator?
I'm not sure, because the original diy author showed photos of his device
and there was no attenuator there.
73, Lukasz
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