Category Archives: SDR

Contest time again

Having and SDR receiver makes it very easy to look at band activity. Today is the start of the two days of mayhem that is called the CQ WW Contest. What is interesting is the number of stations on the air when the bands are supposed to be dead!

A quick look at 20m at 1104 UTC showed wall to wall phone stations. The antenna is still a mismatched long wire so I guess I was missing the weaker signals.

There were a few stations on 17m but more on 15m. That was surprising and a quick listen found that they were all in eastern Europe and Russia. Good steady sigs with no QSB.

What interests me most is that the bands were not ‘dead’, there were people using them. There may not be the exotic DX out there but even that is still possible at times.

So, the only time we speak to each other now is to scream CQ CONTEST followed by 59 QSL. I bet that could be automated with voice talkers and some nifty software, if it has not been done already.

Update 29/10/2018 I dropped in on a mate working /P from the top of a local hill during the contest. He had modest antennas, a doublet and a 20m vertical both quite low. True he had a bit of power but barely 400W PEP. He had worked all over the world including VP8 on Sunday morning. His comments were the same as mine – who says the bands are dead! Don’t wait for a contest get on the air!

 

 

Es’hail-2 satellite ground station

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.

The SDRPlay RSP1A-a momentary lapse

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.