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After a couple of years I completely rebuilt my HF antenna. Based on the same principle of the old one, the new antenna is a dual polarization model. It’s a G5RV wich is possible to “drive” also in vertical polarization. It works from 6 to 160 meters band and the vertical polarization is recommended on the lower band of 160m. To get more info try to see the next video where I present my antenna (english subtitles):
I finally managed to be active again on the QO 100 satellite. After some tests and SSB QSO’s I tried RTTY and than also some SSTV transmission. Considering that currently my signal at the transponder input is not very strong, I never thought I would be able to make 2way QSOs even in SSTV! Below are some nice images exchanged with Greg SQ6ILB from Poland. Stability and synchronism are excellent both in reception and transmission.
I don’t use this cheap handheld often, on the contrary, I rarely use it. Considering the low price of the radio this was not a surprise. To open the antenna just remove the ring nut around the connector and with a small screwdriver widen the rubber that encloses the antenna. Slowly unscrew the connector counterclockwise until the antenna comes out completely. A piece of heat shrink tubing is placed around the capacitor to avoid short circuits.
So quickly I replaced the 3 pF capacitor with a new one. Before putting the cap back on, I did tests that confirmed that the antenna was working perfectly!
It is not a big problem to solve but perhaps it could often happen if the antenna were to hit or bend due to a sudden movement. Since we had the possibility to use the cheap RTL-SDR receivers for amateur radio purposes, I encountered some problem on how was possible to place them in my radio station. Usually fix them directly in the PC USB socket is not an easy way, often the PC is far from the antenna cable inlet and we need to use other long pig-tails to connect the receiver to the antenna. Also the use of longer USB cable so to put the receiver somewhere on the radio desk is not a convenient way, sometime this cable doesn’t support the fast USB transmission not allowing the passage of data. But the biggest problem is precisely where to “lay” the receiver, it is light and small but for this reason it is difficult to manage with its two cables. I solved all this using a simple USB 3.0 female data extention. I got it as a partner company gadget but you can find them on the Internet at various prices. It is very solid, heavy and has non-slip feet. Here follow a couple of photos.
CLASSIC SSTV MMST software
In the first period of my test with QO-100 Satellite, I tried to receive it with a 80 cm dish using a PLL LNB. To “discipline” and get a stable signal I used the SDR Console software option for this satellite. It works very fine and I didn’t need any other correction to get good and stable signals, also for SSTV. After purchasing the converter from DX Patrol I begun to test transmission, first with an homemade 20 turns helix, then with a D-Link 14db panel. I was only capable to do CW QSO, my signal was very weak also with 8 Watt amplifier. So I decided to use the 80 cm dish to transmit and try something new with an existing dish on the roof: it was the 100 cm condo dish for satellite digital channels. I didn’t know what the distance of the second LNB should be, after some internet research I prepared an aluminum corner bracket with a long slot that allowed me a wide range of movement.  The aluminium bracket with the two LNBs
 The front of the 100cm dish Once the bracket was installed I turned on my receiver which I controlled via smartphone and Team Viewer . With small steps I moved the LNB along the bracket looking for the point where the beacon signal was highest. After few minute, and about 18 cm far from main LNB, I found the peak. Some other adjustment for the best signal, now I receive the begin beacon at about -60 dbm with a noise floor of about -95 dbm. It’s not bad at all! Now I can use the 80 cm dish for the uplink, I made some QSOs with significantly higher received signals in CW and with very clear and strong audio in SSB. Other tests will follow.
 The 80 cm dish for the uplink
In the afternoon of the 3rd of September, a strong storm broke down in central Italy with very violent electrical events. Tens of thousands of lightning strikes the peninsular skies while our meteor scatter station at the APA Latina observatory was active. At that time the GRAVES transmitter was not in operation (perhaps due to maintenance) and, although the frequency does not lend itself to good lightning reception, thousands of very strong electrical discharges have been captured by the system. Here a short video of that moment related to the captured lightning.
Meteor scatter radio system is operational again. |
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