I am looking to put together a station for the Es’hail-2 geosynchronous satellite that is about to be launched. Amsat say: “Qatar’s Es’hail-2 satellite will provide: “… the first amateur radio geostationary communications that could link amateurs from Brazil to Thailand.” It will have a narrow band linear transponder with a 2400.050 – 2400.300 MHz uplink and 10489.550 – 10489.800 MHz downlink plus a wideband digital transponder which I will not be using.
At the Microwave group stand at the RSGB convention last weekend I saw a domestic satellite LNB connected to an SDR RX running at 613Mhz. I have the RSP1A and want to try it with an LNB and a 100cm dish for the 10Ghz downlink. The uplink is a bit more complex and I can only think of making a 13cm transverters. There are some kits around, but they are not cheap, and I do not need the RX portion.
The ideal would be conversion of suitable commercial gear. I like to hear about any ideas, suggestions you have especially if you doing something similar. Use email ‘m5fra’ at this site address if you can help. Thanks.
At the RSGB Convention last week I broke my pledge to have a 100% homebrew station. There was a demonstration of an SDRPlay RSP1A right next to the Martin Lynch stand with a small pile of boxes on sale! Not only is it a wide band receiver there is also spectrum analyser software available and all this for just less than £90.
The justification was simple; I build transmitters and need to be able to check the harmonics and other spurious signals to conform to licence regulations. It does not have to be an absolute measurement just the level of the spurious emissions compared to the carrier. And spectrum analysers are expensive.
Then there is the imminent launch of Es’hail, so I need a 10Ghz receiver to listen to it. The conscience clincher was a demo by the microwave group of a modern satellite TV LNA connected to an SDR receiver. Simple. Another reason to get the RSP1A.
And then there is 630m. You get the message, justification for the temptation and I must confess I had a moment of weakness and succumbed. I am trying to atone by finishing the remote tuner.
Not had much time to play but what I have seen is impressive. SDR receivers are incredible, amazing etc. This morning I listened at the top end of 80m for the transatlantic DX spot, 3.798Mhz and was astonished to hear AA8KB at 5-7 on the meter. This is on an untuned inverted L sloper with the high end at about 10m and low end at 6m.
This is a short recording of AA8KB holding the recorder close the the PC speaker.
I can only confess to this lapse and argue that this was a one-off purchase of an extremely useful piece of kit!
The usual disclaimer, no connection with the company and these are my own views.
Update a half hour later. Just gone back to the SDRPlay and found the RF gain was almost turned to minimum.
My first job was as an apprentice at a Post Office HF radio station, Bearley near Stratford-upon-Avon. It was part of the HF point-to-point system that provided worldwide telecommunications. It was state of the art in 1967 and scrapped in 1980.
The station had 50 of the first professional, transistorised communications receivers, Plessey PVR800s. The early versions had some germanium transistors which proved to be unreliable. They were replaced by the ultra modern silicon types!
They were used for telephony, 4 voice channels on double side band reduced carrier. The audio was inverted so that short wave listeners could not eaves drop.
There were also 50 Marconi HR11, valve telegraphy receivers. Each had the capability running 48 telex services on one radio channel using time division multiplex.
As services were transferred to satellites the station took over the maintenance of UK coast stations used for marine communications. They also suffered the same fate. Eventually all HF communications was taken over by satellites and the point-to-point and coast station were closed down. This Post Office film from 1979 shows something of what HF coastal communications in the “good old days”.
It was then end of an era and still saddens me to think that all the old skills have been lost, particularly commercial Morse.
If you want to read more about the HF point-to-point HF radio network, then see this book by Paul Hawkins who worked at the Dorchester TX station. (click the image >)
It is not that the bands are dead, try listening around 14.026 when TT8KO is on! It is just that ops prefer to wait until there is something on the DX cluster rather than put out a CQ or come on for a rag chew.
If we are all waiting for somebody else to speak nothing is said!
At the Newark Hamfest last month there were old copies of Practical Wireless magazine going for £4 each. Having been a reader of the mag since about that time I could not resist.
It is more often the adverts that get me. I remember spending hours drooling over all the ex WWII radio equipment and wishing I had the money to buy some. It did happen a few years later when I was allowed a sol trip to London for the first time. It was a steam train of course.
I was looking for London Central radio Stores in Lisle Street, Soho and did what all kids were told to do and asked a policeman for directions. He looked down on me very suspiciously and asked “now what do you want to go there for lad”. I explained it was for the radio shops and he looked even more suspicious but eventually told me which way to go. I found the shop which obviously had other tenants upstairs who were eager to divert me but the radios were far more interesting!
Here are some adverts and nice little VFO project. I like the sub heading “frequency stability is always a valuable feature”.
There are many more copies available online at this site but you do not get the smell of old magazines.
Work is progressing well on the remote antenna tuner, more pics to follow soon. I am already thinking of the next project and decided I need an accurate 10Mhz frequency source for my counter and other stuff. In the past I have used a surplus rubidium standard and when that popped a GPS locked crystal oscillator.
That was over 10 years ago and things have changed. Used Racal Rubidium boxes are on ebay for between, £550 – £811. Bare bones Rubidium standards which need control circuits are priced at £157. These are often units removed from cell phone installations with an unknown lifespan remaining.
There are also lots of ready built Chinese boxes using 1PPS GPS sync for around £100 but in the spirit of making everything myself either from kits or self sourced components I decided to make my own.
QRP Labs have the QLG1 GPS Receiver kit and the ProgRock kit which makes a very cost effective combination. I have no connection with them except being a satisfied customer. Adding a box, power supply and other bits and pieces the estimated the overall cost will be below £40. The kits are ordered and I will share the build here soon.
See my build of a QRP Labs 20m QCX transceiver here
An Extron ADA4 300MX video distribution amplifier can make a cheap way of distributing the 10Mhz signal around the shack/workshop. See this page.
Very pleased with my new key, a Signal Electric J37 picked up for £10 at the Newark Hamfest today. It was very dirty and tarnished but an hour of work made it more respectable and perfectly functional. I got a lot of satisfaction from bringing it back to life. It is obvious that it has been very heavily used and that makes me wonder who the previous ops were. Nice key and can’t wait to start using it.
This is where I spend a lot of time. It is part of an old converted barn that was a coaching stop between Manchester and Sheffield. It built into a bank with walls 2-3 feet thick which makes it very quiet and cool all year round.
Next project on the bench will be a remote antenna tuner using a couple of Arduinos with an RS485 link. See this F4GOH web page
The construction area. Note the solder fume extract pipe.
The fume extractor is an inline ventilation fan bought from a hydroponics shop. It has a variable speed control and works very well.
The SMD rework area. The heated tweezers will soon be joined by a hot air gun.