Amateur radio (256)

M0RVB

QO100 DATV reception finally

Well, that made quite a difference! I removed the POTY from the QO100 dish today and replaced it with a 'Bullseye 10kHz' LNB sourced from Amazon and advertised as a 'QO-100 Bullseye TCXO LNB'. It's just clamped in place with no attention to position or skew. Winterhill plugged in and instantly I see pictures. The LNB behind the POTY only managed negative values in the MER and D fields, this one seems too work rather well. No idea what happened to the old LNB but these things happen I guess. It's dry and had a waterproof housing. I've used the existing CT125 cable and connectors. Now to put the Winterhill box in a better location than just sitting on a ladder tied on with a bit of wire!! The above photo shows the Winterhill viewer and console on the left and the Quick Tune on the right, all working nicely.

Continue reading...
M0RVB

QO100 next steps...

As I said before I want to use an actual transceiver for QO100 work rather than the Pluto. A precursor to that is a 2400MHz transmit capability and so I now have a nice new (used, new to me) SG Labs 13cm transverter, complete with the PCB log periodic antenna. It is already set up for the correct frequency range and seems fine... so, the next step is move the dish, clear the loft in that area, and get the kit up there. The transverter claims to put out 2W so I can use the existing AMSAT UK PA via an attenuator (max input is 200mW) which should get me 4 to 5W to the dish and has been adequate in the past when using the Pluto. I will first try with just the 'raw' 2W and see if I can get into the satellite. The eventual aim is to use an 80W PA I have ready so I can use DATV as well as SSB or digimodes - that also takes 200mW input - but as yet I don't have a suitable PSU.

Continue reading...
M0RVB

QO100 DATV attempt

Well this got off to a bad start! Ahead of my plan to move the QO100 disk so I can get the electronics in the loft rather than the garage I wanted to test out the Winterhill box to see if I could pick up any DATV on the wideband transponder. The Winterhill box generates the 18V necessary for the LNB so in theory it was just a matter of pulling the coax feed from the bias-tee in the garage and putting that into the Winterhill. That done, I could see the occasional signal but never a picture. Now, I had noticed that the NB beacon strength had dropped a while ago so today I decided to adjust the dish in case it had been knocked. That snowballed! I needed a laptop so I could see the signal strength while at the dish (remember the dish is on the garage wall currently at about 6 foot, so easy reach). Of my two laptops one is a Mac and had no SDR software, the other a Samsung Netbook running Ubuntu and terribly slow. I tried setting up several SDR packages on the Netbook and failed miserably. At this stage I need to state that after a lifetime working in IT and solving problems I now have no time or patience to solve my own, so if something fails it goes to the bin! So, the Mac. CubicSDR refused to even think about installing. I found SdrDX which works with the USB Funcube dongle amongst other, mainly networked things. This worked just fine. Mac out on a lab stool in the shade, SdrDX and the Funcube running, the bias-tee in the garage powered up, a cable fed out the garage back to the dish and into the Funcube... fortunately it didn't all fall over and actually worked. So I adjusted the dish but only gained a couple of dBm more than before no matter what I tried. Oh well... Back inside and plug the Winterhill in. Back upstairs to the Windows PC and now I see locked signals but just not enough signal strength for a picture. I wonder if the LNB is full of spiders... Anyway, now the QO100 kit in the garage is in bits I can't transmit so it can all stay as it is. My next plan is to remove the POTY and install an LNB and see if that gets me any DATV pictures, otherwise I am a bit stuck. The 1.2M offset dish has a clear view of the sky and should be ideal - it worked just fine for SSB on the NB transponder. I never got round to sorting out a GPSDO input for the Pluto but I am about to get a SG Labs 3cm transverter and plan to use an actual transceiver for tx once the dish is moved.

Continue reading...
M0RVB

FT817 first fiddle...

I now have a second Signalink USB complete with the Yaesu cable to go with the FT817. This is actually the third one to arrive here, the second was mis-advertised as having the radio cable - it didn't so it is going back because the price is £20 more than a competitor, a little less than the cost of the radio cable. Serves me right for trying to save a couple of quid! Anyway, FT817 and Signalink all cabled together and no antenna. Hmmm. Ok let's try into a dummy load, should be good enough for across the shack with FT8 running on the Linux box. Nothing received. Ah, it's a Windows box and 1.5 seconds adrift. Sync the time. No change. Ok. Set WSJT-X to 2m and use the front antenna which I have. Nope, nothing sent. It is always a good idea to read the manual before fiddling! Let's change the display to power. Ah. No power... Hmmm. Ok, transmit from the Linux box and I can see that on WSJT-X via the FT817. So it receives fine. Did I mention the manual? Set radio to DIG. Works fine now! Funny, that.

Continue reading...
M0RVB

To switch or patch...

I like to fiddle with stuff but getting antenna a to whatever-it-is b is complex and usually messy. Coax to the loft is all RG213 or Westflex 103 and tends to be a bit stiff and unwieldy so sits attached to whatever transceiver or transverter it was originally put in for. But mixing and matching is my aim. Switches would be equally complex I think. So I am eyeing up a BNC patch panel I used to have in a Land Rover for antenna patching and which has been sitting for 20 or so years sulking in a box of tools. It has 32 holes each designed to take a BNC-BNC through adapter which makes for an extra plug at the rear - maybe a BNC socket wired to whatever kit it is intended for rather than the rear socket would be a better idea. It is the wrong shape of course, better for 4 rows and less width as it makes for long patch leads but if I have all the antennas in the centre I can cut that down - sensible routing is a must. I will still need at least one switch but I have a good one ready to go in. The FT450D is the only thing that needs the three transverters (4m, 2m and 70cm) so no sense in those having both input and output on the panel. Now, where on earth do I fit this thing...

Continue reading...