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Saturday, 13 February 2016

23cm - From a Hilltop - Oh Yes!


You may remember last time I was rambling on about my portable 23cm project; well I had come a little unstuck with what looked like thermal runaway in the PA block.

I managed to acquire a suitable heatsync for the PA and then had another bash at setting the idle current at the 350mA recommended by the PA designer. Eventually, after much trial and error I got the idle current set and there was no hint of the runaway I was seeing before.

So, I took a deep breath and hoked it all up ready for the TX test. The setup was the same as I described last time except I added a power meter at the output of the PA:

I've lashed everything down inside the case in my usual "bodge it and scarper" method and the birds nest now looks like this:

And the whole thing now looks like this:

I'm measuring about 50W output on the power meter, so that'll do nicely.

We've got this Wimo antenna ready for the hilltop which is currently strapped to my Wifes line post:

The return loss of the antenna looks just fine:

By my calculations, if we have 50W out of the linear, that's about 17dBW, the antenna claims 16.something dB gain, even if we call the antenna gain 13dB that makes the ERP about 1KW!

We need to make sure we don't cook too many passing pigeons with this baby.

Local conditions.

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