Radio and rails...

I had a quick fiddle with the box of bits that should by now - in fact by a year ago - be a 5.6Ghz ATV transceiver. I now have a couple of Gibeon flat panel antennas which claim 24dBi as mentioned in the excellent resource on this topic at http://5-6ghz-atv.co.uk/ So, let’s have a play. I got a rather old fashioned Sandisk Photo Album, a slab of plastic that takes 5V and will present photos (and videos and sound files) to a TV via an AV output and the typical red, white and yellow RCA plugs. First off I  needed to make sure this worked. So, what has an AV input… er… Bedroom TV? Nope. An older Sony TV in another bedroom does and so it was plugged up. And nothing. Problem 1, it seems to take an age to turn on in response to its remote control. No switch of course. Problem 2, it would not read anything on the SD card I had with a test card image on. The only clue is it needs a ‘JPEG (Baseline, up to 16 Megapixel)’. No idea what I had produced via GIMP on the Linux box but it would…

I’ve been looking for some time for an affordable (i.e. used) and useful ranged (i.e. not cheap!) spectrum analyser. Obviously I want DC to light but don’t need it and don’t want to sell the house for a bit of test gear. I have a TinySA which is good to 960MHz but I will need a higher frequency range as I fiddle more with microwaves. The ultimate, e.g. a Rigol or Siglent LCD type device is just far too expensive. Nice to have yes but something one would need to be using all the time in order to justify it. Then I came across Satsagen - http://www.albfer.com/en/2020/02/21/satsagen-2/ Satsagen runs under Windows and by default uses an Adalm Pluto as its interface to the real world. The software even does the necessary to upgrade the Pluto to the ‘full’ range of 70MHz to 6GHz (you can do this easily by hand but it’s nice of the software to do it anyway). The software has three basic function too - spectrum analyser, spectrum analyser with tracking, and generator. So, one PC, one Pluto, Satsagen and you get a pretty decent 70MHz to 6GHz spectrum analyser, tracking generator and signal generator. I have…

I’ve been investigating putting some antennas outside and not getting very far. So I got a 2m ‘big wheel’ antenna off a trader on eBay. Plan A was to build my own but, being lazy I purchased a Wimo one. I’ve just installed this in the loft, directly above the shack so no issues of distancing (!) and it is a lot bigger than I had pictured. I now need to crawl under the thing to get to the fan dipole and other less important things such as the plumbing feeding the shower… hmmm. Anyway, it all went together without much struggle and the NanoVNA shows a decent low SWR across the 2m band. I’ve had to rearrange stuff so the 4m dipole is now where the 2m one was and had to be rotated 90 degrees so is now roughly north-south. Initial PSK Reporter results from the big wheel - note both the 2 and 4m antennas are fed from transverters from the transverter store in the Ukraine - showed 2m FT8 results of -14db into Cornwall and -10db into Cork plus a decent spread, and 4m picked up in south Wales so no worse than before. Of course,…

Having now had a chance to take a closer look at the Creed to see why when Y is sent by the TDMS it prints as Z it is clear why! The following shows why... the TDMS is sending a continual stream of Y's and then R's: This is the system between characters, all is well, but... ...this should be a Y, i.e. MSMSM (M = mark, S = space), but prints a Z, i.e. MSSSM. And the R? This should be SMSMS, not SMSSS as shown. SMSSS is carriage return, no wonder then why the typehead remains firmly at the left of the platen. But, checking the waveform output from the TDMS shows it is indeed sending a Y, and with a good square wave. This gets rather mangled when the teleprinter receive coil is connected but still has sufficient peaks to drive the thing. So the issue is between the input to the teleprinter and the selectors. One item to note though is the three photos above are from a video recorded on my iPhone in 'slo-mo' - which proved to be really very useful here! Time to read the manual more closely...

I’ve been planning for a while now to put up an antenna in the garden, but where is the question. I have a 20m wire and 9:1 unun to set up somewhere - ideally I’ll run this up the garden but that goes under the phone line, or actually the end of the wire would be under it. What stopped me was the impending changes for EMF as the unun would be mounted outside pretty close to our bedroom window. So, for a laugh I got another unun to experiment with (yes I know I can make one but the ferrite I had is lost in the workshop moves). Looking at the ‘ideal wire length’ chart 36 feet comes close enough to the distance between the bedroom/shack and the hedge so I cut 36 feet of bell wire and launched it across the utility room towards the workshop as a measure. Tied to the bedroom window reached almost to the far side of the workshop. I reckon I can attach a pole there and attach the unun to the wall outside the shack - there is a convenient airbrick nearby. But, for a laugh I attached said bell wire to…