Well after a real struggle with the semi-rigid cable I managed to finally
get the preamp into some sort of a box. The unit is powered up the coax,
the preamp has been slightly modified to extract the DC supply from the coax.
This also feeds the 18 GHz 12v relay. I managed to find a small quantity
of 12v relays rather than the usual 24v ones.
I must admit I don't really want to put the preamp outside any more instead
I am going to place it where the coax enters the building. That will still cut
down on the distance between the antenna and the preamp.
When no supply is applied to the coax the transmitter is switched straight
through to the antenna in a fail safe manner.
Finally the missing parts arrived and I was able to do some testing of
the 1.3 GHz power amplifier. The output is only about 1 watt at the moment.
There was a lot of lossy RG58 cable between the USRP2 and the test bench hence
the low power.
One thing I found was that if the SMA connectors are not screwed tight you loose
quite a lot of RF. The two black cables inside the amplifier are scrap semi-rigid
cable covered in heat shrink sleeving that I bought on eBay.
I am not the worlds best metal worker but the case, which was made from
pieces of U channel aluminium and flat plate is enough to maintain the PAs
modesty.
I also made some changes to the Software. The idea was to reduce the amount
of memory it requires so it would work better on the laptop. A nice by-product
of the change has been a significant reduction in the system latency.
Well after a real struggle with the semi-rigid cable I managed to finally
