Wednesday, 29 July 2015

Fibre broadband, EMC and ethernet cables

Fibre broadband to cabinet arrived in Ayton a few months ago. For those unfamiliar with the UK terms this means that whereas before we had fibre broadband connection between the local telephone exchange and the Internet, it is now possible to opt at extra cost for our broadband connection to be in optical fibre right the way to the cabinet at the bottom of our street. That is much closer than the telephone exchange.

The distance from here to the cabinet is about 100m, and that is always going to be sent along the copper wires installed underground 30 years ago for the telephone line. That installation dates from the time this house was built. The distance between the cabinet and the exchange is over 1km, so the reduction in the proportion of old copper connection in use is worth having. The claimed (and claimed is all it is) difference in broadband speed this would bring is from 8 MB per second to 38 MB per second. That seemed worth having, so I decided to go for it.

The deals on offer were interesting. Our provider was BT Broadband. They had given a good (but expensive) service on the 8 MB service, after several years of miserable speeds from AOL Broadband (provided by Talk Talk). Whilst Talk Talk offered 8MB but provided 2MB, BT offered 8MB and generally provided it.

By the time of my review, BT was charging as much for the 8MB service as would buy me 38MB fibre broadband with 4 times the monthly download limit. So there was no contest really. John Lewis Broadband was offering higher speeds and higher limits for the same money, so they got the business.

Of course the equipment except the router, and the line, is provided by another branch of BT, BT Openreach. The John Lewis Broadband is provided for them by PlusNet, which is owned by  .... BT. So I am going from BT Broadband to BT Fibre Broadband via two other providers, and getting it for less money. Don't ask me to explain. My business background makes me think that BT should be forced to sell BT Openreach, but never mind about that.

On the run up to switching away from BT Broadband I was bombarded by phone calls and emails threatening all sorts of money I would lose by leaving them, all of which were wrong. So I was reluctant to answer the phone the day before the change, but it was BT Openreach checking that I would be in for the BT Openreach technician (actually a contractor for another company) to come and fit the box at my end.

The Openreach fitter phoned the next day saying that he was at the cabinet and would be with me soon, and he was true to his word. Whilst he got the line running, he could not get the router working nor get Internet access on the new fibre connection, so he left. The John Lewis helpline sorted it eventually. After they told me to turn the router off and turn it back on again (I had already tried that, but theirs was the crucial intervention).

So a successful if not exactly trouble free start. They say I should wait a week before testing the speed, which I will do.

However, on the radio side all hell broke loose. First of all I found quite a bit of noise coming from the switching power supplies of the router and modem. I have come to expect this and I have cut it down using clamp-on ferrites. I will sort it eventually, but there was also a howling tone on 6m and 4m. Also on 2m there was enough signal to make a 59 report on 144.350 and sporadically on 145.500 (unfortunate frequency choices really).

After a few tests, turning off either the Netgear router or the BT Openreach modem stopped the noises. Then, leaving them both on, but disconnecting the ethernet cable between them stopped the noise. The cable was supplied with the Netgear modem and is marked CAT  5E. It looks very cheaply made. I substituted my own CAT 5 cable and the noise got much WORSE. I then noticed that the noise was less if I left the cable vertical rather than horizontal. I then dug out an old CAT 5 cable which is 5 metres long, and draped it down, along the ground, and then up again. This reduced the noise to manageable levels.

Although it seems to be coming from the cable, some of it may still be coming direct from the modem. It certainly seems to be worse when the LAN led is on. Moving the router about seems to alter it, and I think that is the effect of changing the cable to vertical, but it might also be the router.

I did put a ferrite on the long ethernet cable, but I doubt if that will do much. I suspect that the variation between the cables is down to the degree of screening. So I have ordered a "CAT7" screened cable of the type I use with the IC-7100. I will be interested to see who that changes things, if at all.

It seems that CAT7 is not an agreed specification, but the CAT7 cable I use for the Icom seems to be pretty well screened, which might be the main thing.

I still have an open mind about what is to blame here, and we shall see how it pans out. In the longer term I expect to change the £20 Netgear router supplied by John Lewis for something better. Whether the new cable will make a difference I am not sure. The gear is around 10 metres from the 4m antenna and 20m from the 2m and 6m antennas - and about 10m difference in height as well. I think that siting will be important.

Anyway, just what I have come to expect. Latest technology is often incompatible with good old radio.

73

Jim
GM4FVM

Tuesday, 28 July 2015

Data modes - 2. CAT etc.

This is the second of three postings about data modes.

You can find others at:-
Data Modes - 1. Getting Started. Find it here.
Date Modes - 2. CAT etc. You are here.
Data Modes - 3. Software and modes. Still to come.
and a related posting:-
Flex 1500 and data modes. Find it here.

This posting is about Windows. I do use other OS as well myself, but I am not very knowledgeable about them.

Sorry it is so long (someone said my postings were "detailed"!!!). I am trying to cover a lot of situations from someone's first installation, to a setting where a more experienced user has a problem. Apologies.

The reason behind this particular posting is the regular appeals on WSPR.net site which say something like this "Please help, I cannot get CAT to work with my ... (fill in appropriate rig name)."

This happens every few days. Either on the forum or on the chat page, people keep asking for help with broadly the same issue : they have connected up their rig to their computer via a CAT lead or some sort of interface, and it does not work. Usually they have set their software (be it WSPR, WSJT-X or whatever) up, selected the rig in question, and while they can receive and decode signals they cannot transmit or change bands.

The rig is usually the FT-817 as well. Not that the 817 is especially difficult, it is just that the 817 is a very common rig on WSPR.

If you work your way through this posting, and juggle your settings, and then your CAT works, just skip the rest of the posting. Keep checking as you change things. Often the simplest thing can sort it out, and then it is best left alone.

Right so, having connected up the leads (6- and 8-pin min-DIN plugs on the FT-817), we should be in the position of having set it up in the following way as per posting 1:-
Your set-up might look different - you may have bought a data interface which also handles audio, and may even just have one USB plug which carries both audio and data into the computer (creating a "virtual sound card" in the computer). But it all works much the same way.

CAT is separate to audio whatever way it gets into the rig so the first thing to do is to check that the audio is reaching the computer. Find the audio card you are using on the "Sound" tab in "Device Manager", select it on the program you are using and you should find the data mode you are after on your waterfall, or at least the white noise on the band. If your rig has "digi-VOX" (see part 1) you can turn that on and get going to prove everything is working. Once you know that the audio works you can move on to the CAT issue.

If you read part one of this series (here), you will see that it is possible to work the PTT direct using an RTS/DTR signal to a chip. If you have this type of chip to hand, it is an easy way to check that the data is reaching the rig and the PTT is working. You can often use data modes that way, but you will miss many of the features of CAT.

Anyway, those are ways of checking the PTT. Let us suppose that you believe everything is working, but CAT will not trip the PTT or change the frequency on the rig. You may get an error message, such as "CAT - communication timed out".

For the moment I will take the Yaesu FT-450 and WSJT-X as the example we are using. The same general principles apply to all data programs and suites. Here is mine - I am guessing that you already have the audio connected up.
To set up you rig, click "setup",  "configuration" and fill in your station details. On the "PTT method" you select "CAT". Then you click the box "enable CAT" and select the rig from a very long list of rigs. If your rig is not on the list, try a similar one from the same make (if that doesn't work you can still enter your own settings). When you select the rig, the software examines a big list of rig settings (often in a file "hamlib" or similar) and fills in the boxes data bits, stop bits, serial rate and handshake.

You need to enter the CAT port. This is the port created by Windows when you inserted the USB into the computer. You can find that in Windows "Start", "Control Panel" (view under "small icons" on the top right) "Device Manager" and "Ports COM and LTP". In there you will find a series of things, one of which will be a port which leads to your CAT chip. I could suggest all sorts of things to work out which is which, but a good way to find out is to un-plug the USB socket and wait for the COM Port you need to disappear. Plug it back in, note the number, and enter it into the software under "CAT Port".

In WSJT-X you can now check the PTT and CAT Control using the radio buttons for those tasks. It should work. (For WSPR there are no check buttons, so you have to use "tune" or "band" to check CAT)

The purpose of this posting is to show what I do if it DOESN'T WORK.

First thing to check is that the settings from the hamlib (or whatever) library which the software looked up, are the right settings for your rig. First suspect is the serial rate - the speed of the data connection. This causes many problems. Look up the menu system in the rig and make sure that the speeds are both the same - theoretically multiple speeds will work too, but let us keep this simple. On the FT-450 you find it under "CATSPEED", and it is indeed 9600. If not, change it (or the speed in the program) to be in agreement.

Then check the data bits, stop bits and handshake. These may be in your rig manual. 8 data bits is pretty common, you can have 1 or 2 stop bits, and handshake is usually none. I had some problems with the FT-450 to begin with, and I had to use "Hardware" handshake to get it working, before realising that I needed to juggle the rig data timeout settings to get "none" to work. See here for that particular quirk of the FT-450.

Essentially, if the data bits, stop bits and handshake do not work with your rig, you can juggle them about and try to see if some other combination will work. You might want to try something else first - adjusting the COM port settings which comes next here is a more likely problem.

On the face of it, setting the rig and the software to the same settings should make the CAT path straight forward. Yes, and often it does. But we reckon without WINDOWS and the oddities it produces.

When you plug in a USB socket, Windows sets up a COM port to a generic set of parameters. These might or might not suit your rig and software. So if you have set the program and the rig to the same settings, Windows may have set the COM port to something conflicting.

This diagram will not be liked by computer buffs, but it tries to explain what I mean.
As usual, click the diagram to enlarge if needed.

You will see that, inside the computer there is a COM port, and logically, just as the settings need to be correct in the rig and the program, they also need to be right in the COM Port.

Usually Windows will select a combination of settings which work. Even if the speed is wrong, it might be multiple of the speed you need, and everything is fine. But not always.

If you need to reset the COM Port settings, go to COM Ports ("Ports COM and LTP"), as described above, click on your COM Port (you found out its number by unplugging it before), then click "Port Settings" and you will see the settings. To change them, use the pull down boxes. Here is mine for the FT-450. On the same screen is the  "Posts (COM and LTP) in Device Manager (haven't I got a lot of COM Ports!):-
Everything here is fine - the speed, data bits, stop bits and handshake all agree. CAT works.

Turning to something more difficult - WSPR and my FT-817. I have an LDG Z-817H auto tuner. The auto tuner manual tells you to use a data rate of 38400, whereas the WSPR program automatically selects 9600. Even if you set both of the rig and program to 38400, the COM port may not pass this speed. In my case CAT failed. So you may need to reset the COM port if you use this type of tuner. These are the settings that work for me
A similar situation arises with the YT-100 tuner for the FT-897/ FT857/ FT100. The LDG manual suggests you set the data rate to 4800, but in the case is it is an even fraction of the usual rate (9600) so you would probably get away with it.

I  have found on occasion that the FT-817 will not work with 2 stop bits and only works with 1 stop bit. No idea why this happens, and I suspect it is related to some brands of chip.

Moving on from WSPR to Ham Radio Deluxe (HRD) , this can be a useful tool in setting up your data modes. HRD was a brilliant design when first published by HB9DRV, and it is now developed by HRD Software. HB9DRV built into it a search function which will try various options for you. This automates a lot of the fiddling above (but it won't solve the COM Port settings).

If you do not know what settings to use, simply click "Connect" and in the screen enter your rig name and select "Auto-detect" in COM Port and Speed settings.
HRD will then go off and look for the right COM Port, and try various speeds until it finds one that works. If you have checked "always connect to this radio" you will find the port numbers and speed appear in the "preset" tab when you next open it. You can then take those details and use them in other programs.

At that level, HRD is a handy thing to have on your computer, even if you do not use its data programs. In reality, HRD is a VERY useful tool. Not only does it give you good data modes (like PSK and many, many, more), it comes with the main screen which you can use to control your rig. More of HRD in a later posting.

Where HRD does come unstuck for me is that, so far, I have not paid for the latest version from HRD Software. I am still using version 5.1 which was the last freely distributed version. I like the free version of course, but its rig library does not include recent rigs, particularly the Icom IC-7100. If  I bought the latest version, it would of course.

After a while of developing HRD, HRD Solutions stopped distributing HRD 5.1. No reason why they should distribute the free version while they were trying to sell better versions at the same time. You can still find HRD 5.1 for free on the Internet, and it still works.

This brings me to Icom. Icom does not use CAT but have their own version, CI-V. It differs in various ways, but principally in having the rig model as part of the data exchange. That is neat for refining what functions can be controlled, but it means that libraries of rig data need to keep being updated. With CAT you can find something similar, or just insert your own values for things, until it works. With CI-V you need HRD (or WSJT-X etc) to send the right rig name code.

So I use my old version of HRD with my IC-7100, but as HRD does not have the settings for the IC-7100, I use settings for the IC-7600. HRD 5.1 does have the settings for the IC-7600. Icom call the IC-7600 "7A" for CI-V purposes, and I changed the settings in the IC-7100 to identify itself as a rig named 7A. Then I have to use IC-7600 as the rig name for WSJT and WSPR etc.

There is nothing wrong with CI-V as far as I can see. In many ways the simple 3.5mm plug it uses is far easier to handle than tacking CAT onto an 8pin DIN as Yaesu do. But as I have not found the money to buy the latest version of HRD I have to use a work-around for the IC-7100.

WSJT-type programs just ignore CI-V and call it CAT, but they do work with CI-V and Icom rigs in general.

The IC-7100 is particularly fiddly to set up with WSPR. However, like all these things, you just have to play around with the settings until they work, and then you never need to do it again.

Until you change computer.

Or change rig.

Then you have to do it all over again.

Next instalment will deal with some of the software programs and modes.

73

Jim
GM4FVM

P.S. I should have mentioned.... if PTT works on CAT but there is no tx signal, check the settings for tx audio in the software. Not strictly a CAT issue, but if you look at the FT-450 WSJT-X settings above you can see Data selected from a choice of Data or Mic. Some rigs accept data as if it came through the mic circuitry, but others, and the Kenwood TS-590 did this if I recall correctly, need the data option checked. There is a similar option to choose in HRD and some other software.
Just another thing to think about ...

Thursday, 23 July 2015

Is this the end of Solar Cycle 24?

Is this the end of Solar Cycle 24? No.

But it is clear that the graph points downwards when it comes to solar activity.

These graphs come from the US NOAA, featured on SolarHam, and feature their measurement for the Solar Flux and the Sunspot Numbers:-

You can see that they predict that we are on the down slope of the curve, which was smaller than last cycle. A trend towards lower peaks has been noticed for several cycles now.

We tend to home in on the smoothed graph, but things go up and down a lot. We can hope for a few spikes upwards for quite some time yet.

As  I write (23 July 2015), the solar flux index is 89 and the sun spot number is 35. The two numbers are related, so I tend to watch the Flux Index as it is measured directly with reference to radio emissions from the sun.

I begin to get interested when the Flux Index is over 100. Over 100 and the 10 metre band might open to F-layer propagation round the world. If it was to stay over 200 for some days, the six metre band might open for F-layer propagation. At 89 nothing is happening at all.

I have read various things about the relationship between solar activity and Sporadic E. For a 36 hour period 22:10 on 20/7/15 to 11:06 on 22/7/15 I had zero spots on 10m WSPR. This is pretty well unheard of here in July. Right when you would expect to find both Sporadic E and F-layer propagation, there was none of either. For F-layer we do have the "summer doldrums" but the Sun has no seasons, and the flux number applies to all seasons.

Looked at from here, Sporadic E often occurs when the solar activity is high. For example, today there was an opening in Finland, Sweden and Norway on 10m and 6m which was variously called Es or Auroral Es, and the K index is high which indicates incoming mass ejections etc.

The K number and the solar cycle are not directly linked. But I can certainly see high K number causing Es here (at 56 degrees North). The link between the K number and the solar cycle is confusing. Many say that Es is best at solar minima, others say the opposite. Similar conflicting claims are made about auroral activity.

For me, I like to think that whatever the decline in solar activity, my favourite modes of propagation, Es, Aurora and meteor scatter will not be too badly affected. And in this solar cycle we have had only brief spells where the flux index was above 200, and therefore no 6m F-layer propagation at all here. So it looks like I do not have much to lose ... but the Sun will do as it pleases. That huge eruption which will knock out the World's power supplies might be just around the corner.

Despite all this, I am keeping up my new interest in 40 metres. It will be a long time before the solar cycle picks up again. Or at least it will be if the Sun follows the pattern many predict. I am sure that the occasional solar mass ejection will keep me busy on VHF for a long time.

Predicting solar cycles is a pretty sketchy science. Look at this from Wikipedia discussing the different predictions for Solar Cycle 24:-
Prior to 2006, the difference was very drastic with a minority set of researchers predicting "the smallest solar cycle in 100 years."[5] Another group of researchers, including those at NASA, were predicting that it "looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago."[6]
Well, it certainly was NOT the most intense cycle since records began, and NASA were wrong about that. Perhaps the current predictions are wrong too.

Could I become a 40 metre band enthusiast?

I doubt it.

73

Jim
GM4FVM

Wednesday, 22 July 2015

Data modes - 1. Getting started

This posting is supposed to be one of about three - this one dealing with the basics, one with CAT-type rig control, and one with the software and modes. There might be others in the series too. I will try to link them all together too! Just like World Peace, it will be great once we finish building it.. 

Since my first data contact - RTTY on 20 metres using a Creed teleprinter 35 years ago - to my latest - 4 metre meteor scatter using computer generated FSK441 on 20 July 2015 - nothing fundamental has changed.

That may sound odd, but I think that although I have ditched the mechanical teleprinter and replaced it with a computer, the basic idea remains the same. You generate tones, you insert them into the audio section of your rig, and then you take the received tones, insert them into the audio section of your decoder. So at its simplest, you only need an audio cable. Then you need to find some way to switch the rig from receive (rx) to transmit (tx), but not if you just want to listen.

It really can be that simple. An audio lead is all that is standing between many amateurs and the world of WSPR, moon bounce, meteor scatter, PSK, JT65 data QSOs, photos beamed from the International Space Station, slow scan TV, ...

Back in the 1970s it seemed a lot simpler, you just made up the audio lead. These days you are bombarded with fancy solutions, many of them very expensive. Recently, when I received my Yaesu FT-450, I started off using it on data modes with just a single audio lead. So I am writing this to try to dispel some myths that the whole subject is too complex to deal with.

One thing I will not deal with here is packet radio. Packet was (or is?) a sort of amateur version of the packet switching formats behind Internet communications. We got there first in many ways, but the telecoms companies quickly adopted packet switching to offer Internet over the phone system, so I will not be dealing with that. Nor will I deal here with any system which uses switching rather than audio tones. For a time rigs offered ways to send RTTY direct from the teleprinter, and these still hang around, but they are not really practical for many modes we use now.

Conveniently, a lot of modern rigs have a standard socket for data tone input/output. It is a six pin mini-DIN, shown here on an earlier picture I took of the back of my FT-450 ...
It is the one on the bottom left marked, handily enough, "DATA".

Many rigs made in the last 20 years have this more-or-less standard 6pin DIN socket. Check in the handbook of your rig to make sure. For example, the Yaesu FT-817 handbook has this diagram of the pin connections:-
As we are not looking at a tx/rx control yet, (PTT for push to talk), we only need to think about the data tones in and data tones out, and indeed only one data audio out connection (there are two). Again from the FT-817 manual:-
And now we see a difference between my simple audio lead and what Yaesu show. They show the rig connected to a terminal unit with a PTT connection. For the FT-817 you need to switch it between tx and rx if you want to transmit (but not if you just want to listen).

However, we are dealing with the FT-450 to start with. It has a "Digi-VOX". Digi-VOX is like microphone VOX, so when you have it turned on, it monitors the digital input via the mini-DIN plug for an audio signal like the tones you are trying to send, and if it sees them, it switches to tx. Simple (but you have to get the level and sensitivity right). If there is a tone you are sending the rig, you are swtiched to tx, if not, then you are in rx. Perfect. All you need to send PSK or whatever is the audio lead from your computer, and when the rig detects the audio tone it will go into transmit automatically.

Here is the audio lead I used to get started with the FT-450:-
You can make them up yourself though I bought this one on eBay. Not exactly high tech. You plug the mini-DIN into the rig and the 3.5mm stereo plugs into the sound card of your computer. There are two 3.5mm stereo audio plugs as your computer sound card has separate audio in (sometimes marked "mic" or "line in" at different signal levels) and audio out (sometimes marked "speakers" or "headphones").

Set the audio levels right and you are now ready to download one of the data programs from the Internet (FLDigi, HRD, WSJT-X etc) and off you go  ... provided that your rig has digi-VOX.

The FT-450 has digi-VOX, so has the FT-897. I seem to recall that the TS-590 has too. But the FT-817 does not, and neither does the IC-7100. So for them you will need some sort of switching for the PTT as well as the audio lead.

Digi-VOX is not really perfect. It works and I have used it many times, but the problems which arise can make life difficult. For example, any transient click on the audio line will cause the rig to go into transmit. If you forget that you were working data and decide to play your latest tunes on iPlayer, they will get transmitted on 20m or wherever you are. There are ways round this, but it is probably better in the long run to take control of you PTT.

You can buy data interfaces which have built-in data-VOXs in them. So all you need to do is to plug the audio leads into the computer and the mini-DIN into the rig, and the switching is taken care of automatically. This turns a rig without digi-VOX into one with digi-VOX, but does not really solve any of the problems. Simple though.

At this stage you will also have noticed that you are plugged into your computer's sound card, in the case of a lap top you have silenced the speakers, and in the case of a desk top you have had to unplug the speakers. To solve this you can install a second soundcard (I have 3 installed, and two "virtual" ones - more on that later). You can buy cheap USB sound cards for a few £££ on eBay. Then you plug the sound card into a USB socket and plug the rig into that. Here is an example of what a USB sound card can look like :-


This is a simple cheap one, there are other designs, and you can get all sorts of expensive and bigger ones. The principle is the same. I have compared more expensive ones and I have to say that I cannot find any real difference in the better ones, and the cheap ones seem OK for data purposes. You might need a USB-USB extension lead to separate it from your computer as it is very wide, but apart from that the cheap ones seem fine. You can of course connect speakers to the cheap USB sound card and use your in-built sound card on the computer for the rig.

If you add another sound card you will need to select it for data purposes in your software, and adjust the audio levels to suit. More about that in our third posting on data modes (I hope).

Right, so we have our audio connection made. How can we control the PTT if we do not have or do not use digi-VOX? Well, the Yaesu diagram above showing the RTTY terminal unit connected to the FT-817 shows a handy terminal on the terminal unit marked "PTT". Sadly, our computers do not come with a PTT terminal. So we need to add one. This can be done simply by using a switching chip connected to a USB socket on the computer. The will turn your rig to tx as required via the mini-DIN plug. That is the simple way, but the more complex way is to do it via CAT control (which is the subject of part 2 of these postings).

So let us stick with simple PTT switching. For a long time you could buy simple combined audio connections and switching controls on eBay. You can still find ones using CAT control, which allows you to do more things. But for now we are sticking to non-CAT. The sort of leads you found were these:-

This still shows the two 3.5mm audio plugs, the 6 pin mini-DIN data plug for the rig, but also another USB plug for the computer. Inside the box is a chip to convert DTR or RTS signals from the computer into a simple switch connecting the rig PTT to earth. That will switch your rig to tx whenever required by the software. The chip shows up as a peripheral device on the computer in the "COM Ports" list on the "Device Manager" screen. So it might appear as COM3, for example. You then set up your software to send (DTR or RTS) PTT signals to "COM3" (or whatever number Windows gives it, if you are using Windows) and that turns the rig to tx. Now you have automatic tx/rx switching, and if you try to play music after you have finished operating, the rig will stay in rx and you will not transmit the music.

What we have done now is go from the top drawing to the bottom one:-
The photo of the lead shows the chip mounted in a box along the lead, though you can get leads on eBay with the chip at the USB plug end (note though, once again you may need a USB-USB lead to separate the wide plug body holding the chip from the USB sockets).

This just gives us simple audio in/out and PTT. It does not give us CAT control. CAT is useful as it allows you to control the rig frequency from the software. CAT opens up all sorts of possibilities, but that is for the next posting in this series. CAT can be really tricky to set up, but once set up, it runs well.

If your rig does not have a CAT connection, or your software does not support one, or maybe does not need one, then this is as far as you need to go with connecting up the rig to the computer (but see below about earth loops and isolation).

Now that we have a working system to convey audio and PTT between the rig and the computer, there are still a few issues to clear up.

Firstly, the use of a simple audio lead can bring some problems. The audio lead can pick up RF from the rig, so it needs to be well screened (and ideally short too). Also, and more tricky to resolve, it can help form an "earth loop" between the rig and the computer. This allows mains hum to be picked up and it is very difficult to fix. I have had all sorts of issues with earth loops over the years, but only while dealing with audio equipment. I have never had the problem with data links for radios. However, it is a good idea to isolate the rig from the computer. It is also a good idea to isolate the PTT line too, so that neither has a direct DC link to each other.

Isolation can be done in various different ways, but using audio transformers is popular, as are opto-isolators for data isolation. Here is a look inside the box of the lead shown above, and you can see the chip and the audio isolation transformers:-

The transformers have yellow insulation on the cores and sponge on top to locate them physically. The chip is between them to the left.

Some of these data leads were pretty badly made. Most used chips made by Prolific. The chips may or may not be real Prolific chips: some are fake chips. You can still get the fake ones to work if you know how, despite Prolific's reasonable attempts to render them useless. Then again, if the audio transformers are not good quality you find that the audio bandwidth is small which is limiting for some modes like JT65 or PSK where you are offered a waterfall. With poor bandwidth you get narrow waterfalls. They do work though.

Secondly, given the poor bandwidth, you might want to replace this composite PTT/audio lead with just simple audio lead and a "CAT" lead. You can buy simple CAT leads on eBay for most rigs. Here is one for the FT-817:-
In this case it has a USB on one end with the chip built into the plug, and an 8 pin "CAT" plug for Yaesu rigs on the other end. I have various versions of this one, with D9 or 3.5mm plugs, depending if it for Yaesu CAT or Icom CIV fitted rigs. But whatever, this is still all you need for data operations. As the drawing above showed, the advance beyond just an audio line at the the top of the drawing, is an audio lines and something to control PTT (CAT just controls PTT and some more things). BUT CAT is often troublesome to set up, so more of this in a later posting.

Thirdly, I am talking about simple set-ups. The sort of audio lead you can make yourself, or even the data lead if you feel adventurous (yes, I have made one myself). But you can buy all sorts of things cheaply from eBay and even go to ham shops and spend a fortune. Nevertheless, I am trying to point out that all this hides a simple concept of two leads, one for audio, and one for data. Yes, you can buy a box that does it all for you, but it is useful to know how it all works.

Finally, very recent rigs such as Software Defined Radios (SDRs like my Flex 1500) or less basic radios (like my Icom IC-7100) now have USB plugs which allow direct digital connection to a computer. This saves both the audio lead and the PTT or CAT lead. Both of those rigs create "virtual" audio ports inside the computer. Then you get digital audio right from the rig into your processor, and it saves issues with bandwidth, earth loops, USB sound cards and the whole palaver. Still, it is good to know what "virtual" stands for, just a software version of the sound card.

Beware of some rigs which have USB connections but which do not set up virtual sound cards. I think that Alinco make one like this, which allows you to control the frequency of the rig, but you still need to take the audio out down an audio lead. Although you miss the extra quality and ease of a digital audio line, you just work with an audio lead instead. Just like I did with RTTY back in the 1970s. Nothing changes, really.

More on CAT and modes/software later, I hope.

See you all again soon.

73

Jim
GM4FVM

Friday, 17 July 2015

VHF Sporadic E, a better day.

At last, a better day today.

I had a "sort of" hunch that it might get better during the day when I noticed both Jaap PA0O and Chris 4X1RF on 4m WSPR. They obviously thought things might improve. You may recall that Chris runs the very station I worked as my best DX on 1mW on 10m, so the path exists if the ionisation allows it to open at 4m.

A German station posted on the cluster than he had heard the 4m beacon on Cape Verde Islands.That beacon is on 70.220MHz. He seemed to think he was listening to a spurious output, but it looks real enough to me. Now that would be DX .... but I know Cape Verde has been worked from Finland, so no records to be had there. Still, it would be a good one to work.

At one stage I saw this as my 6m WSPR map, but it actually got better on 6m later and it was still going after 23:00 clock time.
Nae bad though, with three continents and quite a few DXCCs too.

For a while I was reaching Chris on 6m but not on 4m. Jaap reached Chris on 4m at 17:02 (he and G3ZJO were heard by Chris earlier in July while I was in Canada -- grrr). I kept a close watch on the maps, trying to see if 4m might open from here.

However, soon it worked for me on both 4m and 6m ...
Power Reported Distance
Date Call Frequency SNR Drift Grid dBm W by loc km mi
   


   
    
 2015-07-17 17:44  GM4FVM  70.092463  -21  1  IO85wu  +37  5.012  4X1RF  KM72ls  3832  2381 
 2015-07-17 17:34  GM4FVM  70.092463  -24  2  IO85wu  +37  5.012  4X1RF  KM72ls  3832  2381 

Of course 4X stations do not have the ability to transmit back - so far. Maybe one day. But for now, just to be heard at 3832km on 4m is good enough for me now. My previous 4m record (3276km, but a two-way contact of course) has been broken in the sense that at least I was heard. And more to the point, it shows it can be done.

I know that 4m has been received in North America, but usually that happens from much further South than here. To reach 3832km with my modest station is pleasing for me. I have yet to work Bahrain or United Arab Emirates, though others have. Later maybe...

Then at 18:02 I worked SV1OH (KM18 2762km) and 9H1BT (JM75BT 2550km), both on 4m SSB. Now, either of those would be nice enough, and indeed 9H1BT's signal was such good SSB that I remarked on it to him. At 59 signal strength, I could hear everything as if it was an FM broadcast station, whereas often I just get compressed "communication" quality signals. But it was really being heard by 4X1RF on 4m that made my day.
Sure enough, the map looks a bit lop--sided. There were no stations in Europe on 4m WSPR except the UK, Netherlands and one in Northern Germany. So other than tropo, there was not much chance to work any of them apart from Chris in Haifa. And that was the way it turned out. It took all day, but it worked in the end.
I have put 40m WSPR on the attic antenna for tonight. That should help me come back to my senses.

73

Jim
GM4FVM

Monday, 13 July 2015

Back from Canada and summer doldrums

We have been in Canada - or Nova Scotia to be more exact. A direct flight from Glasgow takes about the same time as one to the Eastern Mediterranean. It is very rare for us to venture outside Europe, so this was a special occasion for us.

Top is the clock tower in Halifax, and bottom is the St Paul Island lighthouse and museum at Dingwall, on Cape Breton Island.

This was not a radio trip, though I did see some antennas of course. A car parked next to me at the St Francis Xavier University in Antigonish with various whips, bases and an FT-857 on the dash. But that was it radio wise, apart from the brilliant satellite radio in the hire car. We do not go in for that in Europe much.

We did see a bear, which was unusual. You do not come across many bears around here. There have been calls to reintroduce bears and wolves to Scotland, but so far only some bird species and beavers have been officially returned to our habitat. Having seen a bear close up in the wild now, I think we might be able to do without them.

Moving on, yesterday was a day of solid operation on 10m and 6m WSPR. Total results for the day were:-

Power Reported Distance
Date Call Frequency SNR Drift Grid dBm W by loc km mi
 2015-07-12 18:24  EA4GDE  28.126111  -26  -1  IN80dk  +23  0.200  GM4FVM  IO85wu  1718  1068 
 2015-07-12 12:34  GM4FQE  28.126104  -28  0  IO86qg  +37  5.012  GM4FVM  IO85wu  56  35 

Two stations heard on 10m, not very strong or even very far away, and zero on 6m. Nobody heard me, on any band, all day. There was raised solar activity which knocked HF back, there was also some Polar Es which missed me, TF3ML/P was heard on 2m meteor scatter but not worked, and the resultant aurora was at 04:00 and affected ... Canada.

Still, things may improve.

73

Jim