First attempts at 3cm
So Láďa OK1DGR and I started tests with satellite PLL LNB and RTL SDR (classic red usb dongle) na 3cm. LNB is typo Amiko L-104, which cost whole 80 CZK, absolutely incredible price. These LNBs are commonly available on Inet in eShop, etc..
The manufacturer states excellent parameters:
– noise figure 0,1 dB
– profit 55 dB
– classic SAT ranges and controls for polarization and RX band (13V, 17V a 22kHz)
– temperature range -40 up to + 60 °
So I pulled an older, unused Sat antenna out of the ground, he attached it to a photo tripod and we started testing. I use my favorite SDR Sharp, I set the LNB offset, he entered the middle of the band and then things happened…
Before I turned on the RX, I turned it around “somehow there”, where I was expecting the OK0EA beacon signal. Immediately after the start of SDR, a signal of about 10dB appeared, it was enough to direct and was stable around 20-25dB. Then we took the LNB out of the dish and turned it towards the lighthouse. The signal was still 8dB! Incredibly, with regard to it regarding to it, that due to the weather we had to move under the roof and the neighbor's cottage stands exactly in the direction of the lighthouse…
In terms of stability, the LNB is doing great, ale USB RTL SDR – it's another coffee 🙁
After the first switch-on, the beacon signal marched quite a bit, so we started looking for the culprit. Instead of SDR, we connected a receiver from Mr. Icom to the LNB (PCR-1000) and it was clear – instability, which we attributed to the LNB in the first attempts, strangely enough, it was the RTL SDR USB dongle that was to blame. I thought, that it would help stabilize it a little – So we stuck the nice SDR-ko into a piece of insulating pipe for heating (miralon or whatever it is), leave it on for a while and then it was pedaling like clockwork. The result can be heard in this file– OK0EA v mp3.
Finally, a brief summary – distance to the lighthouse is 134 km, outside the neighbor's house there is no further elevation in the route, but as can be seen, we didn't mind much there 🙂
The result surprised us both a lot, we expected, that we will hunt something at noise level and wandering across the band, but the opposite was true. In the end, I did not make an exact correction of the MF frequency in SDR #, so the resulting beacon frequency on the PC is “as if below the zone”, but that's not a problem, it is only one constant in SW. The parameters of this device surprised me so much, that the next step will be an attempt to listen to the EME beacon, there is a professional dish 120cm with a stable fit… 🙂
TNX for Peter's background, OK1IN http://ok1in.nagano.cz/
