ISS SSTV - 15th to 17th February 2019

Yesterday I stumbled, merely by chance, on what I thought might be a potential SSTV transmission from the International Space Station, which I did tweet about, confirmed by Trevor M5AKA, and I had a look on the Amsat UK website, my home shack radio for 2-meters is still the QYT KT-8900D and the antenna is currently just the 2/70 TX capable magnetic mount scanner antenna, with rubbish thin coax feeding it, on top of a radiator by the window and received the ISS no problem at all.

Today knowing about this, I was able to decode it, thanks to Carl 2E0EZT who mentioned the Robot36 SSTV app in one of his videos on YouTube (a channel I ended up finding out about thanks to Callum M0MCX of DX Commander fame so both are being credited for this), using nothing more than my phone's inbuilt microphone I was able to decode an image from the ISS when it passed over between 1350 and 1400UTC, my first successful attempt at SSTV rx from the ISS, and pleased is an understatement.

When I initially stumbled on the transmission yesterday purely by chance I had mounted the radio onto something to allow air to circulate around it, and also allow it to be raised a little higher, I have the ISS and a few local repeaters along with both 2-meters and 70cm simplex channels all programmed into the radio, and was turning the dial when I heard the transmission, bearing in mind I was unaware that the ISS was overhead at that time so it really was just luck, and on tweeting about it I got my confirmation.

Though I do plan to do some ATV (Fast Scan) I have for a while wanted to play with SSTV but lacked facilities, turns out to receive it all I need is a mobile phone, perhaps the same to TX it too? we'll see

And this is a screencap from Robot36 of what I received today

Not too bad for a first attempt and with equipment that is certainly not the best.

A good reason to get into the hobby, you aren't limited to receiving communications from stations here on good ol' planet Earth, the challenge with the ISS is, of course, knowing when the astronauts are on air and knowing when it will be passing over, and normally you only have a window of a few minutes. in my case it was 10 minutes and I made that count to receive the SSTV image here.

In some cases it is possible to talk to the astronauts but during this weekend the ISS 2-meter station was being used for SSTV so that would not have been possible.

73 de 2E0EIJ

Portable ops and pager intermod follow up

Today I went back to the old racecourse in Richmond and gave another go at portable operation there but this time using my KT-8900D, this radio suffered from the intermod issue as well but nowhere near as bad as the VV-898, as for me to hear it I had to open the squelch (which is shown in the video I took).

I managed one QSO, and almost got another one too but there was some confusion on S20 as to who was calling who, no matter, one was better than none at all.

This has drawn me to the conclusion that I must now build a notch filter (or spend US$90 or so on one pre made which I'd rather avoid), as my intent is to block out pagers I can use the pager frequencies and the RTL-SDR to tweak it and suppress the pager transmissions so they don't cause intermod.

Looking online there are some designs for these, some use a coil of wire and capacitors and screened enclosures, of course what I need is something that can basically work to TX on 2 and 70 without any issue so I will look at that of course, however the ultimate aim is to stop the pager noise dead in its tracks.

I will obviously test the final design with the worst offending radio, the VV-898, in the field at the old racecourse.

73 de 2E0EIJ

homebrew dipole working

Last night I got my homebrew 2-meter dipole antenna tuned and working while the rain held off, to use it I clamped the upright to an open window and the boom with the antenna on the end was outside the window, GB3CD was able to be accessed but it seemed to be below my squelch and a little in the noise, as were a couple of the stations on the S12 net I discovered, one in Darlington could hear me as I could hear him just fine, from the location given the station in Darlington was on the other side of Darlington to myself up near the retail park and car dealers, this was enough confirmation the antenna was in fact doing its job satisfactory, GB3HG and GB3IR obviously were not going to prove a challenge for the antenna given their locations.

Tomorrow if the rain holds off and the weather is good I may set up a portable station on Richmond's old racecourse with this antenna, the radio I will take I have yet to decide, also undecided is if I will go QRP or not, my VV898 can go as low as 5 watts (QRP levels) however the KT-8900D can only go to 10 watts at its lowest settings, after all this antenna is meant to be a portable design requiring nothing more than a screwdriver to disassemble the support from the boom, the VV898 may of course need reprogramming depending on how it is currently configured.

The next antenna I'd like to make is an antenna to work the FM satellites as I have still yet to do that, this dipole is my third successful antenna, the first being the T2LT for CB work and the groundplane antenna for 2-meters that was my original homebase antenna.

The coax on the antenna itself is a short run of RG58 to a BNC, this meant I have had to use a BNC-PL259 adaptor and a SO239 coupler to connect the feedline, which is the repaired feeder that was from the groundplane antenna after it was cut and it works great and is fitted with a crimp on PL259.

I shall see what happens tomorrow and see what stations I can work simplex if I go portable.

73 de 2E0EIJ