Sunday, 12 February 2017

Radio History?

A little while after moving to this QTH I joined the local radio club. Always a good way of getting to know local radio amateurs in a new area and an opportunity to chat to like minded people and share knowledge. One evening I mentioned that I used a few SDR receivers in the shack. A number of the club members were not familiar with SDR and to cut a long story short I ended up offering to bring along a couple of my receivers and give a demonstration.
Whilst I was planning my demo I realised that as the club meetings are in the evenings and HF conditions have been very poor lately it was quite possible that we would have very little to listen to. Then it occurred to me- Most SDR software has a facility to record. Not simply to make an audio recording, although it can do that as well as required. The clever bit about recording from an SDR receiver is that you can also "record" a whole bandwidth of signals. In the case of my Elad SDR radio it can receive and record up to 6mhz of bandwidth. The picture below shows it receiving the full 6mhz using the SDR console v3 software.

Using this facility I was able to record part of the spectrum in the daytime, when the bands were busy and use this to demonstrate the SDR software and receivers.

The received part of the spectrum can be recorded onto a hard drive (or any other media). When played back you can tune through the spectrum (in the example above from around 11 to 17 mhz) using whatever mode you want.
In effect you have a snapshot of that bit of the HF spectrum which you can listen to as if you were sat at your receiver when the recording was taken.
This set me thinking, if only we had this technology years ago. Today we would be able to tune through the HF bands of the 40s,50's 60's as if we were there! 
I wonder if anyone is recording the bands on a large scale now. The downside of this is at the moment these recordings use a lot of space. The recording in my picture above was for a 10 minute recording of 6mhz of spectrum which used 7gb of storage. I reckon to record the whole 30mhz of LF/HF (if you had a receiver with such a wide bandwidth) for 24 hours would use in the region of 8.4 tb. If you were attempting to record for any length of time you would need a massive amount of storage. But just imagine if we were able to tune through the bands of yesteryear!........................................

Sunday, 14 August 2016

It's Been a long time but.............

I am still active. The blog has been neglected, I kept meaning to update it but have only just found the time. I moved QTH at the end of January this year and have been busy with lots of things. Once I had unpacked at the new place I wanted to set up a basic station.Initially I set up an HF station with my Icom 7000 and a very temporary half sized G5RV inverted V held up by a fibreglass pole at about 6 metres high.

 7 months later, you guessed it, the "temporary" antenna is still there! It has however been joined by my 6/2/70cms vertical (which needs to go a little higher)

 and two antennas for SWL, my trusty Wellbrook loop

and a "Boni Whip" active antenna

Here it is in place, well for the moment at least. If all is well with it I will be getting some self amalgamating tape on those connectors. The Boni Whip is an adaptation of the mini-whip designed by PA0RDT. I bought this antenna a couple of years ago but with the awful noise problems I had at my old QTH never bothered to put it up. I thought I would try it here. The whip on the antenna is tiny, maybe around 7cms but initial results seem encouraging, it is particularly good on the lower bands. There is some debate  on line as to whether the antenna should be grounded or not. I found mine to be much quieter noise wise after I did this.

And here it is on top of its mast.

Sunday, 29 November 2015

QRT? Not Quite

I haven't posted here for quite a while. Its not that I have lost interest however the shack has largely been dismantled  and most of the antennas taken down as I am waiting to move house. Of course these things take time and even if all goes to plan it may be a few months before I am at my new QTH. In the meantime the only antenna still in use is my Wellbrook active receiving loop along with a couple of receivers in the shack. So for now I am almost totally an SWL. This would not be so bad if I didn't have a very bad noise problem here. I have been unable to trace this noise. It disappeared for a couple of months in the summer, but now its back. I don't think it comes from my neighbours properties as a while back we had a power cut in the street and checking with a battery powered receiver the noise was still there. The noise it at its worst below about 7 mhz, it wipes out parts of the medium wave, as well as the 160m and 80 metre bands and affects 40metres to a lesser extent.

Here's an example of the effect on medium wave.

I am just hoping my new QTH will be a bit quieter on HF!!

I still have 2 metres FM and HF on my Icom 706 in the car so can operate mobile however 2 metres in this area is a wasteland with very little activity. With the house move and the prospect of no antennas for a while I have even got involved in an area of radio that I had always been rather critical in the past- D-STAR. I will talk more about this in future blogs, it is a way of still getting some radio activity in at the moment but it is cheating and doesn't of course have the same magic at operating on HF!

Sunday, 16 August 2015

I had a little time to play radio this weekend so managed to work a few special event stations that were running for the lighthouse weekend. Conditions were not  that good and the noise problem I still have here doesn't help but I managed a few. One surprise was working EI0LHL on 20 metres. I can't remember ever working an EI on 20 before, the skip isn't usually that short on that band.

The noise problem here is very strange. A few weeks back we had a power cut in this area. Listening around on a battery operated radio at that time showed the noise was still there. So my noise is not caused by a near neighbour with a PLT device as I had suspected. Stranger still about two weeks ago the noise disappeared. Sadly it is now back again but perhaps isn't quite as bad as it was but it still makes a mess of Top Band (160m) and Medium Wave.

Tuesday, 16 June 2015

6 Metres

Caught my first six meter opening of 2015. Some pretty strong signals on the band when I switched on around 1930 UTC. Managed to work a few with just 50 watts from the Icom 7000 to my vertical. Nothing spectacular but it was nice to work Italy, Spain and France on 6 metres.Switching on the "radio" computer to enter the calls in my electronic log I found the computer had died! I havent time at the moment to investigate the problem but this PC is quite old and in fact was given to me for free. Possibly time for an upgrade I think. In the meantime I am glad I still keep a paper log in the shack.

Saturday, 6 June 2015

A new (but old) addition

Here is the latest addition to my Shack. As a young shortwave listener in the 1980's I always wanted one of these receivers but back then it was of course well out of my price range. It is the Icom R70
I managed to get an immaculate example of this receiver at a reasonable price and I am very pleased with it. It is a heavy, well built set, it feels far more substantial than the Kenwood receivers I have from the same era.
It is however quite a quirky receiver in some ways. Each time you turn the receiver on it defaults to the same frequency (15mhz in general coverage mode and 7 mhz in HAM mode). In addition you tune in 1 MHZ bands and you must use the UP and DOWN buttons to go to the next Mhz segment. In other words if you are at 7.999 Mhz and keep tuning, rather than go up to 8.000mhz the R70 rolls back down to 7.000mhz. Quite an odd way of doing things. Still as an HF receiver the R70 is excellent and I think this one is a "keeper".

Wednesday, 8 April 2015

Silent Keys

Its never good in this hobby of ours to see the words "Silent Key". In this case the Amateur was not known to me (He was a relative of a work colleague) and in fact he has passed away over three years ago. I was asked to help his widow value and dispose of the radio gear.

I found a well equipped station with An 200watt Yaesu FT1000mpMk5, A Kenwood TS870s (having tested  it here I am very impressed  and various other transceivers. All in good condition and as I later found in good working order.  I was told in passing by the silent key's XYL that one of her relatives had advised her to simply throw the gear in the radio shack away! Luckily she knew enough to realise that this was not a good idea. It did make me wonder however how much gear is potentially destroyed like that. There were also one or two less valuable but perhaps more interesting pieces of gear:

This Sony ICF2001D was a state of the art portable maybe 20 years ago or more. This one was in very good condition and its still an excellent receiver. This one has been added to my shack!

What is in this box?

Its actually a multimeter,  A CT471C I think used by the military (possibly the Royal Air Force?)

Here it is with the lid removed.

Inside the lid are the test leads and some sort of probes.

This is a heavy unit, not like the little lightweight plastic multimeter I have!

For VHF/UHF there was a Yaesu FT4700RH dual band rig. Although this was quite an old radio I was surprised to find it had a CTCSS unit fitted and it appeared more sensitive on receive than my Icom IC7000

As radio hobbyists we know that all of this equipment has a value. We may not know exactly how much each item is worth but we would have an idea or, at least, an idea of where to find out. It is easy to forget that to people who have no interest in the hobby (this may include relatives/loved ones) may not realise that this equipment is worth anything. To the untrained eye this is "junk" metal boxes that could be thrown out.
Equally there are people out there perhaps less than honest that may take advantage and clear shacks out paying only a fraction of the true value. What can we do about this? Perhaps list the main equipment we have and let those close to us know that some of this equipment is valuable .