My amateur radio station in 1991

I was recently looking through some old photographs and I found some pictures of my old radio shack and aerials from when I still lived at home.  These photos would have been taken in the second half of 1991.

The first photo is the inside of my ‘shack’ which was really just one side of my bedroom.

My radio shack in 1991 showing my FT-736R

My radio shack in 1991 showing my FT-736R (click for a much larger version)

From the left is a dumb terminal which was connected to the PK-88 TNC for accessing the local packet radio mailbox.  Then there’s a PSU against the wall with a postcard of the Greek island of Paxos on top of it (this is how I’ve been able to date the picture).  Next to that is a Yaesu desk microphone, a Yaesu FT-736R multimode for 2m and 70cms and an external speaker for the wireless with a rotator control box on top.  Just next to this and barely visible is a Morse key, a limited edition key which was hand made by Mike, G4ZPE and I wish I still owned that.  Finally on the right side you can see a BNOS VHF 100W amplifier sitting on top of a BNOS dummy load.  On top of the 736 is an SWR meter and the aforementioned AEA PK-88 TNC.
On the wall are some coax switches which allowed me to change between a dual band vertical aerial or beams for both 2m and 70cms.

Moving outside.

My aerials in 1991

My aerials in 1991 (click for a much larger version)

Luckily my bedroom/shack was right at the back of the house on the top floor, ideally located for my aerials with the cables coming in through the window.

On the top of the pole on the left is a 48 element multibeam for 70cms.  Jaybeam aerials had a reputation for being very solidly built and this multibeam was a prime example of that.  Below it is a 9 element F9FT Tonna for 2m and below the rotator is a TV aerial.  On the pole on the right side is a Diamond X500 vertical for 2m and 70cms and below the second TV aerial is a small vertical dipole which was used to access the AX25 packet radio network.

Close up of the 48 ele multibeam and 9 element Tonna

Close up of the 48 ele multibeam and 9 element Tonna (click to make it bigger)

This setup worked remarkably well, especially considering that the location wasn’t particularly high above sea level.  I successfully entered a number of contests on VHF and UHF using this relatively modest station with good results and although I never won anything, I was generally well placed.  It was using this setup that I made the one and only auroral contact I’ve ever had!  I did enjoy chasing DX and working new squares on 2m and 70cms.

I don’t think I still own anything that appears in these pictures although my mum still lives in the same house and the brackets on the back now just sport a TV aerial – Mounted on a 20ft pole and naturally the highest in the area!

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Listening to the Camb-Hams from the Isle of Islay

The Camb-Hams are on their usual annual pilgrimage to Scotland and I’ve worked them on a few bands and modes.  I’ve also made a couple of recordings of them on 40m CW, showing how well the Kenwood TS-590SG can read Morse Code and on 40m and 80m SSB.

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Learning to code in Python – Hello Raspberry Pi!

After my posts about building an APRS RX iGate, I entered into email discussion with Alan, K2RHK who pointed me towards his website specifically to see his experiments in APRS.  While looking through his site, I noticed he’d recommended a book for those looking to learn how to program a Raspberry Pi.  I mentioned that this was something I’d just started doing and Alan contacted a friend of his, Marjan Bace at Manning Publications who very kindly posted me a copy of the book we were talking about called ‘Hello Raspberry Pi!‘.

I’ve only just started learning to program in Python but this looks like a fun and interesting book to get me going.  I’ve already sussed out some Python simply by examining existing code and tweaking it to do what I want but it’s good to get a proper guide to start me off with the basics.

Thanks Alan and Marjan!

Hello Raspberry Pi! by Ryan Heitz from Manning Publications

Hello Raspberry Pi! by Ryan Heitz from Manning Publications

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What can be achieved in twelve hours of 20m JT65/JT9?

WSPR is great, I enjoy running WSPR and seeing how far I can transmit using very low power but there are a couple of drawbacks.  I appreciate this will sound as though I’m knocking WSPR but trust me, I’m really not.

Firstly, it’s not a QSO mode.  I accept that many years ago, some QSOs were made using WSPR but that was in the very early stages of development and I don’t believe that the software is there to actually facilitate that any more.  I find it frustrating to hear people say “Oh, I had contacts all over the world yesterday on WSPR”. No, you didn’t.  You transmitted and someone received you, that doesn’t necessarily make a QSO.

Secondly, although WSPR is incredibly good at penetrating around the world, just because someone in (say) VK land heard your 200mW WSPR signal with a strength of -28dB, that doesn’t mean the band is properly open and that you can complete a QSO using SSB or CW.  You almost certainly can’t.

This is where the low signal data modes come in, specifically JT65 and the newer JT9.  I’ve written about JT65 a lot, I couldn’t have completed my original QSO365 without using JT65 and I discussed JT9 here.

Rather than run WSPR for a day, I thought I’d spend twelve hours yesterday just receiving JT65 and JT9 signals on 20m.  In theory, I should be able to work any station I can hear using these modes.  I fired up the latest version of WSJT-X which includes JT4, JT9, JT65, QRA64, ISCAT, MSK144, and WSPR at just after 09:00z, configured it for JT65 and JT9 reception, switched it to 20m and let it sit there receiving and uploading everything to pskreporter to produce the map below.

The results after twelve hours were quite astonishing.  I know these modes are popular but I don’t think I realised quite how popular they’ve become.  You can click the following two images for much larger versions.

Map of stations heard on 20m JT65 and JT9 over a twelve hour period

Map of stations heard on 20m JT65 and JT9 over a twelve hour period

Over a period of twelve hours I received 2,124 individual transmissions from 554 unique transmitters spread over 74 countries.  That’s quite incredible.

List of countries heard on 20m JT65 and JT9 over a twelve hour period

List of countries heard on 20m JT65 and JT9 over a twelve hour period

To test my theory that all of these should be workable, I made four QSOs in the evening.  I worked Venezuela, Japan, Puerto Rico and Brazil, all with JT65 and all using just five watts.  I still like to run bucketloads of power when it’s appropriate but for these low signal modes, you really don’t need to run a lot of power to make contacts.

The low power/low power data modes aren’t for everyone but they’re not difficult to use and are a great way of getting the most out of a small to medium sized station.  They drag every dB of performance out of inefficient aerial systems and it’s no surprise that my first ever QSO with VK back in 2011 was using JT65 and a short ‘long’ wire aerial.

If you’ve never tried these modes, I encourage you to give them a try.  You’ll be happily surprised at what you can work.

Posted in Amateur radio, Data, HF, JT65, JT9, QSO365, WSPR | Tagged , , , | Leave a comment

More new test gear for the shack

Back in 2012 I wrote about some new test gear that I’d bought for the shack.  Well time doesn’t stand still and it’s always nice to have new toys in the shack, especially if they’re useful.

My miniVNA Pro always did me well but recently I’ve started doing things on higher frequencies, such as building aerials for ADS-B reception and it’s frustrated me that I’ve not been able to fully test them.  With that in mind, earlier this year I bought myself an AAI RF Vector Impedance Analyser N1201SA from Banggood.

AAI RF Vector Impedance Analyser N1201SA

AAI RF Vector Impedance Analyser N1201SA

This is a cracking little piece of kit which covers from 137 MHz up to 2.7 GHz in 1 kHz steps.  It can measure SWR, resistance, reactance and S11. It’s not stupidly expensive either at around £130.  Being battery operated and fairly simple to use, it’s a very good piece of equipment.

The only downside to it is that there’s no way to save the measurements it displays apart from taking a photograph of the screen.  There’s no denying that it looks good though, here’s a plot of my Diamond X510 from earlier today.  It’s also not a full blown VNA so it can’t be used for such things as measuring the performance of filters.

AAI N1201SA scan of my Diamond X510N on 2m

AAI N1201SA scan of my Diamond X510N on 2m

Despite these downsides, if there was an HF version of this analyser, I’d be all over it.

The next logical step for me was an upgrade to my old miniVNA Pro.  It’s a fantastic piece of kit that’s served me very well over the years but I wanted something to cover higher frequencies.  I looked into a number of items and decided that the best thing for me was to change to the newer miniVNA Tiny.  Despite the name sounding as though it’s a downgrade (Pro to Tiny), it’s actually a decent upgrade as it covers from 1 MHz up to 3 GHz which is far higher than I can ever think I’ll need.  It looks quite similar to my old VNA, it’s just a little smaller and has a different connector.

miniVNA Tiny from mini RADIO SOLUTIONS

miniVNA Tiny from mini Radio Solutions

One of the first things I did with this was to test my new Diamond X510N vertical which I put up a couple of weeks ago and here are the results on 2m and 70cms.  It’s encouraging to see that the 2m measurement matches up with the N1201SA image above.

Both these images are clickable for much larger versions.

Diamond X510N 2m SWR measured with miniVNA Tiny

Diamond X510N 2m SWR measured with miniVNA Tiny

Diamond X510N 70cms SWR measured with miniVNA Tiny

Diamond X510N 70cms SWR measured with miniVNA Tiny

Finally I’ve been able to get my hands on something I’ve wanted for quite a long time and it serves multiple purposes.  I’ve wanted an accurate power meter for measuring the output of my WSPR/QRSS transmitters. It’s all very well having a super-duper QRO meter but when trying to measure down to a couple of hundred milliwatts, that’s not exactly suitable.

I bought myself a Yaege FC1-Plus Portable Frequency Counter which covers a massive 10 Hz to 2.6 GHz from 409shop.  Not only is this a frequency counter (which is useful by itself) but it’s also a power meter which is good up to two or three watts.  I wouldn’t want to put any more power into it.

Yaege FC1-Plus Portable Frequency Counter

Yaege FC1-Plus Portable Frequency Counter

If you’re looking to buy one of these, be aware that there are two models.  The FC1 and the FC1-Plus.  If you want the power meter version then you must buy the FC1-Plus.  It’s a little more expensive at around £50 but if you want it as a power meter then it’s worth it.

Here’s the display in frequency counter mode, monitoring my WSPR transmitter.

Yaege FC1-Plus in frequency counter mode

Yaege FC1-Plus in frequency counter mode

This ties up within a few Hz of the frequency I’ve got my GPS based transmitter so I’m happy with the accuracy.

What I was really interested though was power.  I fired up my WSPR transmitter into the meter in power mode.

Yaege FC1-Plus in power mode

Yaege FC1-Plus in power mode

This reads fractionally higher than I was expecting although I am running a higher voltage to the output stage of the U3S transmitter.  I have no reason to disbelieve the accuracy as I’ve been assured from a couple of sources that these meters are pretty much spot on.  Even if it’s only within 10%, I’m still happy but it does mean that I’m probably running a little more power on the lower bands than I thought.

I think that good test equipment in the shack really is essential now – Long gone are the days when we only used an SWR meter to check and align aerials and although a lot of amateurs only use commercial products, it’s still useful to be able to test performance to make sure everything is working properly.  I play around with low power experimental transmitters so this sort of kit is essential really.

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A new record – G to ZL on 60m QRSS

Toward the end of March I ran WSPR and QRSS on the 60m band for a couple of weeks.  I did some experiments on 60m nearly three years ago which gave good results and I was keen to improve that.

I posted on the new Knights QRSS list to announce that I would be active on 60m in the hope that some of the grabbers around the world would switch to 5MHz to listen for my signal and I was very pleased that a number of people happily switched over for a while.  It’s an unusual band because there aren’t that many countries that have a 60m allocation and they don’t always match up around the world.  Of course, anyone is free to receive on the band so that helps.

I was very pleased to receive the following reports.

G6NHU to ON4CDJ on 60m - 208km

G6NHU to ON4CDJ on 60m – 208 km

G6NHU to G3VYZ on 60m - 400km

G6NHU to G3VYZ on 60m – 400 km

G6NHU to VE1VDM on 60m - 4,637km

G6NHU to VE1VDM on 60m – 4,637 km

G6NHU to W4HBK on 60m - 7,293km

G6NHU to W4HBK on 60m – 7,293 km

All very good but no improvement over the tests we did before.  There’s one more though.

G6NHU to ZL2IK on 60m - 18,130km

G6NHU to ZL2IK on 60m – 18,130 km

This is a stacked image and is still quite weak so let’s zoom in a bit.

G6NHU as seen on ZK2IK's 60m QRSS grabber

G6NHU as seen on ZK2IK’s 60m QRSS grabber

Here’s a capture from Pete’s eight hour grabber showing my received signal repeating itself around twelve times between 06:00z and 08:00z on 23rd March 2017.

Eight hour ZL2IK grabber showing G6NHU on 60m QRSS

Eight hour ZL2IK grabber showing G6NHU on 60m QRSS

As far as I’m aware, this is the first time that QRSS signals have been successfully transmitted from G to ZL. I’m using my Hans Summers U3S transmitter with around 250mW output into a random length doublet, just 30ft AGL at the east end, sloping down to 20ft AGL at the west end.  Pete, ZL2IK is using an Icom IC-R75 communications receiver locked to a GPSDO frequency standard (no drift) and a combined 80/40m dipole fed through an ATU to match it to 60m.

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Returning to data modes after an enforced break

My shack computer is an Apple iMac.  For a few years, I’ve operated a lot of data modes and been very successful in data contests.  I’ve always enjoyed data modes and in 2012 I operated GO6NHU to celebrate the London 2012 Olympics exclusively using data.

Back in 2015, Apple released a new operating system called El Capitan and as soon as I upgraded to it, I noticed some problems with fldigi (my favourite data software).  I would switch to transmit, and roughly 60% of the time, the transmitted audio would come out of my iMac internal speakers instead of being sent to the radio.  It was the same with WSPR and any other software I tried which sent audio to the wireless via the USB cable.

My Kenwood TS-590 is connected to the iMac by a single USB cable.  The radio has a built in sound card and fldigi simple recognises that for everything it needs.  Data (CAT control) and audio pass down the same cable and PTT control is via data VOX.

This had worked perfectly for a number of years but broke when I upgraded to El Capitan.  I tried many things to attempt to resolve the problem, software reinstallation, replacement cable, reset the radio and other fixes but nothing worked.  One of the later patches to El Capitan did include a fix for external USB audio devices but that didn’t help either.  I found this article which went some way to explaining what the problem was although there was no recognised fix apart from reverting back to OS X Yosemite.

I simply stopped operating data modes and when Mac OS Sierra was released, I tried again but had no further success.  It was just the same.

Recently I did some more testing, I set up clean installations of both OS X El Capitan and Mac OS Sierra on an external drive to see if I had the same problem – I did.  I then built a clean version of OS X Yosemite on an external drive and it worked perfectly.  My hardware is OK, it’s just the changes to how Apple handle external USB sound cards that is the problem.  Searching the internet found a lot of people with exactly the same problem although frustratingly, it’s not universal.  I know of people with the same model iMac who don’t have any issues.

It was time to finally find a fix.  I decided to bin the USB cable and go the old fashioned way, using an RS-232 interface lead and an audio interface.

The first thing to find was a USB to RS-232 adapter.  I went with a UGreen USB Serial Interface cable based on the PL2303 chipset because it claims to be fully compatible with Mac OS.  I also needed a null modem cable to connect to the back of my Kenwood TS-590 which was simple enough to get hold of.

That completed the CAT side of things and it worked perfectly well.  I had full control over the radio from the computer and the next thing to deal with was the audio.

It’s well documented that to avoid earth loops, hums, audio feedback etc, one should use an audio isolation transformer.  I would need two of these, one each for transmitted and received audio.  There are many of these available for a few pennies on eBay or Amazon but most of them are shipped from overseas with a lead time of weeks.  This wasn’t good enough for me so I drove to the Rapid Online trade counter and bought two Vigortronix VTX-131-001 line matching transformers.  These were mounted on a piece of veroboard and fitted into a small box along with screened cable for the audio in and out.

Home brew interface for data modes using two audio isolation transformers

Home brew interface for data modes using two audio isolation transformers

I considered using a metal box but decided that as all the audio cables were screened and as I’d put decent ferrites at each end, a metal case wasn’t absolutely necessary.  If I get any problems, I can always change the box afterwards.

With this all built and working, I connected one side of the interface to the accessory socket of my radio and the other side to the audio input and output of iMac to test.  It worked perfectly and I was back on the data modes.  However, this wasn’t ideal as it meant that I’d effectively lost all normal sound on the computer and I had to be careful to avoid inadvertently transmitting computer audio!

I did some research to try and find a USB audio device that would work properly with the latest version of the Mac OS and found reports that a fairly cheap card, the Creative Labs Play! 2 was compatible.  I bought one from Amazon because their returns policy is superb and I knew that if this didn’t work, I’d be able to return it. It arrived the next day and as once I’d loaded the drivers, it worked like a dream.

Finally after around two years, I’m fully back and able to work data modes using my iMac.

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