Last November’s EME receive testing has definitely made me want to try to improve the system for receive, and then to see if I cam make an EME contact using my very limited system. The first step was to try to improve the preamp, and following a suggestion from Brian GM8BJF I have built one using the PGA-103+ MMIC.

That’s it, built somewhat crudely using a pcb “etched” using a Dremel type tool, and after many years without proper construction , with me getting used to using a new soldering iron and also back into soldering surface mount components. My hands are also not as steady as they were either – I am definitely getting older!

Initial bench tests suggested that the preamp is at least stable, so I decided to see what it’s like when trying to detect Sun noise. It worked out quite well; it seems to give rather better results than I was obtaining with the BFG541 preamp. From the graph (below) it looks to be more like 7-8dB of Sun noise rather than the 4-5dB I was getting in November. I should probably have tested with that preamp as well but it went cloudy, and since I was finding the Sun manually I needed to see it! From what I can pick up online there’s no particular solar activity just now, and the 10.7cm solar flux has actually gone down a little since November.

The blue horizontal lines are where the antenna was pointing at a quiet bit of sky and the red horizontal lines where it was pointing at the Sun (easier to find!). The wobbly bits in between, especially looking for quiet sky, show how noisy the environment is here; the antenna sidelobes must always be picking up something! The connections to the preamp were also maybe a bit loose, hence some of the other up and down wobbles! Ignore the waterfall, which covers just the last few minutes; the graph below covers probably 30 minutes.

The arrows at the end show another useful test – A is where I disconnected the feeder at the antenna; B is where I switched the power off the preamp; between B and C is me disconnecting feeders; and C is where I disconnected the feeder from the FT-817, so after that is just the noise from the receiver.

All in all, quite pleasing. I must now get the second 15-ele section finished which will improve the antenna considerably, and also get the preamp boxed up.