AmateurRadio.com

The weather forecast wasn’t promising, even though the morning was fine. But I was keen to get out on the fells. Yesterday I spent a couple of hours making an antenna specifically for Wainwrights On The Air operating and I wanted to try it out. So I headed for Broom Fell, LDW-169.

I’d had the idea for this antenna for a couple of years but hadn’t got around to making it. I was going to call it the WOTA Pole. As, for reasons I will come to, I’m unlikely to be publishing a detailed description of it, I’ll give you the outline of it now. It’s a Slim Jim made from 300 ohm flat ribbon cable, housed in a tube made of white UPVC electrical conduit. The tube breaks down into four sections for easy carrying using UPVC jointing pieces. It’s a similar idea to the SOTA Beams MFD except that is a half wave dipole and has a T piece with a coaxial balun and can be used vertically or horizontally. The Slim Jim should theoretically have some gain over the dipole but it can’t be used horizontally, which is no disadvantage as 99% of WOTA activating is done on FM.

One reason I haven’t used the MFD very much is the difficulty in deploying it. The antenna is provided with two velcro straps so it can be attached to a convenient fence post. Unfortunately our hilltops don’t often have convenient fence posts on the summit. My intention with the WOTA Pole had been to stuff the antenna in my rucksack for support so the radiating element would be above head height. Unfortunately UPVC jointing pieces aren’t very strong and it’s impossible to lift a rucksack onto your back whilst keeping a 2 metre long antenna perfectly vertical to minimize the strain on the joins. As I lifted it up I heard a crack and the antenna fell to pieces!

I didn’t see any damage. It was quite windy up there and I thought the culprit was the wind, plus perhaps I hadn’t pushed the jointing pieces tightly enough together. So instead I decided to strap the antenna to a convenient fence post which fortunately Broom Fell just happened to be equipped with right by the summit cairn. You can see the result in the photo. Lords Seat is the fell on the right in middle distance, with the Skiddaw range further away on the left.

Sunday lunchtime is not the best time to go WOTA activating. I think many chasers are busy filling themselves with roast beef and yorkshire pudding and nowhere near their radios. However Colin 2E0XSD was on frequency having been following my progress via APRS. He gave me a 59 plus report on the new antenna. After a couple of fruitless CQs I started to think that was going to be the lot, then Geoff GM4WHA came up, followed by Malcolm M0XAT. Then no-one. As the wind was bending the WOTA Pole rather a lot I took it down. I then tried a couple more calls using a helical antenna and got Mark MM1MPB and Tony G1OAE. Finally Colin 2E0XSD came up again to say I was only 4 by 3 on the helical antenna. The WOTA Pole had made a huge difference. It’s just a pity there hadn’t been anyone further afield listening at the time.

I walked down the hill a short way to get out of the wind and have the sandwiches and coffee that Olga had made for me. While I was down there I thought I would have another try at hoisting the antenna on to my back in the rucksack. Then I noticed that one of the UPVC jointing pieces – the one at the top of the lowest tube that takes most of the strain – had cracked. When I tried to get it aloft a piece broke away completely and the antenna fell to the ground. Another idea bites the dust. Literally!

On the way down I was pondering what I could do to make this idea work. Clearly the Slim Jim itself performed very well. In fact if anything it worked a bit too well on receive. The VX-8GR receiver exhibited clear signs of overload. I’d noticed this before when I’d used that radio with the MFD. I should really use the Motorola GP-300. Ironic that a radio that cost me £1 at a rally works better than a fancy Yaesu costing more than £300!

The problem with my WOTA Pole idea is the mechanical design. If I’d made the tube two one metre pieces instead of four 50cm lengths it would be stronger. But having something sticking 50cm above the top of my rucksack would be a nuisance when walking under low branches or ducking under fallen trees as I actually had to do on this walk.

Perhaps I should give up the idea entirely and try to make a rucksack mount for BNC fitting antennas. Then I could use the telescopic 5/8 wave that I usually use on less windy days fitted directly to the radio. What do you think?

The first bit of live data I received from my APRS VHF propagation alert reflector was a warning of a possible Sporadic-E opening on six metres. I was rather surprised that there was Sporadic-E this early in the year, but I went to the DX Sherlock website and sure enough contacts had been reported between a station even further north than here and one in the Czech Republic. I then clicked on the map to see the actual contact details and was surprised to find they were WSPR spots!

I went to the WSPR website and sure enough the same signals were shown. I decided to fire up WSPR on 6m myself but by then the OK station had gone and no new spots appeared from anywhere.

I have been, and still am, somewhat sceptical of the value of WSPR in showing VHF Sporadic-E propagation. One of the characteristics of Sporadic-E, particularly at the start and end of the season or on the higher frequencies like 2m is that it is very fleeting. A signal can be there for one minute, literally, and gone the next. On the other hand, signals can be really strong when reflected by Sporadic-E. WSPR is designed for detecting weak signals under steady propagation conditions and uses a 2 minute transmit cycle during which the data is transmitted very slowly. It seems to me that what you want to detect Sporadic-E is a mode with short transmit cycles where the data is transmitted quickly, perhaps something more akin to the modes used for meteor-scatter. I wonder if K1JT could come up with something?

Nevertheless I am very interested in anything that helps to detect VHF openings that might otherwise go undetected. I plan on WSPRing more on the 6m band, as long as there are others doing likewise so there is a chance of being received!

I have just set up an ANSRVR notification group (the APRS equivalent of an email reflector) called CDGVHF. The purpose of the group is to alert interested subscribers in the Cumbria, Dumfries and Galloway area to possible openings on the 6m, 4m, 2m and 70cm bands.

The APRS alerts make use of the email alert service of DX Sherlock which sends alerts of possible band openings customized to the subscriber’s location, based on DX Cluster spots and other reverse beacon information. I have set up a subscription to send alerts of possible band openings workable from the IO84 grid locator to a special email address on the G4ILO’s Shack web server. Using a feature of the cPanel web hosting, the email is “piped” to a script written by me in the PHP language. This extracts the subject header of the email which contains a succinct description of the alert, shortens it as much as possible and then sends it as a message to the CDGVHF ANSRVR group, which then forwards it to all interested subscribers.

Why is this better than just subscribing directly to receive the alert emails? Because I can now receive the alerts on my APRS-equipped hand-held, which should greatly reduce the chance of missing a good band opening because I wasn’t in the shack at the right moment.

The K144XV eventually turned up late on Thursday afternoon. After the board modifications had been performed, installing the transverter module was easy following Elecraft’s exemplary instructions. I had to remove the KIO3 module in order to remove the KXV3 transverter module and replace it with the KXV3A, which has a couple of additional connectors for the internal transverter, then replace the KIO3. I also had to replace the side panel of the K3 with one that has some extra holes for securing the transverter. The stiffener that runs across the top of the case is also replaced by one with a cutout where it passes over the K144XV.

Due to the lateness of the hour I was a bit tired and also focussed on getting the job finished so the shack could be restored to normality so I never even thought about taking some pictures. The module comes as a complete screened box not a bare board as shown in some of the pictures on the Elecraft website. It is quite a little beauty and the way it all fits into the K3 is a work of art.

Although described as a 10W module the instruction manual states that you should get at least 9W with 1.0mW input to the transverter. I actually got about 11W so the power output comfortably exceeded spec. At my noisy location I can’t make any meaningful observation about sensitivity – any half decent 2m radio will be sensitive enough. But I did notice that S meter readings are extremely low. I see no movement at all on a clear frequency despite the noisy location and a repeater that lights all the signal strength bars of my TM-D710 registered just S4 on the K3. I never take any notice of S meters anyway so I’m not unduly bothered. The amplifier “brick” I will use with this has its own built-in preamp which will boost S meter readings if I want.

The 2m amplifier I have was designed to be driven by an FT-817 so it only requires an input of 5W. I found that I needed to reduce the drive to the transverter to a mere 0.15mW to achieve this level of output. I don’t know how accurate the low level output power settings of the K3 are but the relationship between 28MHz drive in and power out is definitely not linear. However the signal on SSB sounded pretty clean when monitored on the FT-817.

The calibration of the transverter local oscillator is done using software, not by trying to tweak a trimmer capacitor by a fraction of a hair’s breadth, which is a blessing. There are two local oscillators in the transverter to provide coverage of the full US 2m band (144 – 148MHz) using the same 28MHz – 30MHz range (interestingly the top 2MHz is not disabled in European rigs.) The transverter module is calibrated at the factory and you have to enter the calibration values into the K3 using the configuration menu. I checked the result using my FC-1 frequency counter and also my FT-817 and it appeared to be accurate to within 100Hz which is about as good as I can get. Later I listened on the GB3VHF beacon frequency and waited for the beacon to come out of the noise. I believe this beacon’s frequency is GPS locked. The frequency appeared to be out by 120Hz so I was able to adjust the calibration value and get it spot on.

The signal to noise ratio on a weak FM signal is definitely better on the K3 than with my other 2m rigs but I don’t see the K144XV as being the solution for people whose primary interest 2m FM. One reason is that a 2m mobile rig is cheaper and allows you to monitor and work 2m FM at the same time as using your K3 for something else. Another is that the K3 doesn’t really handle channelized operation very well. The memory system has improved considerably since the early days but using the VFO to scan through memories rather than a click stop rotary control doesn’t work for me, especially due to the laggy response of the K3 to the turning of the knob.

But I think the K144XV is an excellent option if you want to work 2m DX. The receiver sounds quiet and clean and having all the QRM fighting and weak signal detecting tools of the K3 available on 144MHz is a real bonus. Now I just have to wait for some 2m SSB activity to try it out!

I have had a bit of a change round in the shack recently. Since getting the Kenwood TM-D710 which is used for 2m FM which is the vast majority of my VHF activity, the Icom IC-910H has really been under-utilized. 70cm is a dead band here and there isn’t too much 2m SSB activity. Besides, I never really liked the Icom. So I decided to swap it for an old Spectrum Communications transverter that I have and sell it in the new year.

The Kenwood has been moved into the “second rig” operating position. And the desk mic I used with the Icom is now attached to the Kenwood. I had some CAT5 UTP network cables which are terminated in the same type of plug Kenwood uses for a mic connector, so I cut one in half and made up a cable for the desk mic. Despite being unshielded (UTP stands for Unshielded Twisted Pair) there doesn’t seem to be any RFI even at 50W. And the reports I have had so far suggest that it sounds good.

The Spectrum transverter runs about 20W output. This is less than I would like for SSB. My plan was to set the transverter drive so the peak output was 5W and use it to drive a 50W linear amp that I have. But when I set the power to 5W, as soon as I put the cover on the case it dropped to 1.5W. So I thought that perhaps the whole thing needs realignment.

Unfortunately it did not go well. The transverter, which I bought umpteenth-hand in a private sale some time ago, had obviously suffered the depredations of the ham-fisted twiddler. Two of the ferrite tuning cores in the Toko coils were cracked and could neither be adjusted nor removed so they could be replaced. Despite this, the transverter receives pretty well.

However, while trying to realign the transmit side to solve the problem of changing power output when the case cover goes on, I noticed that there was often power out when the key was up. There was clearly some instability present. Although I could adjust the trimmers so there was no unwanted output, I could not eliminate the changing output as the case cover is put on. I do not have the test equipment (a spectrum analyzer) to be sure that the output is clean and I started to have doubts about the whole thing.

I did not want to risk wiping out the neighbour’s TV reception whenever I use 2m SSB. So I decided to scrap the transverter and order an XV144 internal transverter module for my K3. It is on its way, and hopefully will arrive in the UK before the increase in VAT takes effect.

I think I may have discovered one of the best kept secrets in radio. I have been thinking, off and on, about how to make a very low power 2m FM transmitter in order to get weather data into my APRS system wirelessly. A circuit using the Motorola MC2833P chip is quite easy to build, and I even have one in my parts box, but a custom crystal to multiply up to 144.800MHz would cost about £25 to be made which just isn’t worth it.

One day I was browsing looking at various APRS articles and came across a tracker someone had built using a VHF transmitter module from Radiometrix. I had come across this site before but thought that a) these modules were only for transmitting digital data not the AFSK that we use, b) they were not manufactured for amateur frequencies and c) they were not available in one-off quantities for individual private purchasers. I submitted an enquiry, stating that I was interested in purchasing one TX1 low power (10mW) module on 144.800MHz if the price was within my amateur budget, and was amazed to be informed that they would be happy to offer the module for £13.00 plus carriage and VAT, with a lead time of five days. In total it came to not much more than £20 which is amazing considering many professional electronics suppliers specify a minimum order value greater than that.

The picture of the module is much larger than it actually is – the pins are the standard 0.1in spacing. As I am nowhere near actually needing to use it at the moment, I hooked it up on the breadboard to give it a quick test. The module does indeed accept an audio input: as described in the data sheet you should bias the input pin and then feed it with audio at a couple of volts amplitude via a blocking capacitor. I lashed it up to my FoxTrak APRS tracker and a braaap was received and decoded by my 2m APRS gateway which was enough of a test to be going on with.

There are several other products with interesting ham radio applications on the Radiometrix website. The HX1 is a high power (300mW) version of the module I bought. With the addition of a PA I could turn my FoxTrak into a standalone tracker. Even by itself it would probably have quite a decent range from the fell tops. Also of interest is the SHX1 which is described as “a small multi-channel 25kHz narrow band VHF transceiver with up to 500mW RF power output, usable for 144MHz band amateur applications.” I think you could build a little hand-held transceiver with one of these, just for fun.

Many of these products aren’t in the online shop so you can’t find out the price or buy online, which is probably just as well as I could see myself ordering some more of these toys for something to play with over Christmas. I would certainly be interested to hear from anyone who has used, plans to use or has some ideas for using any of these little radio modules from Radiometrix.

Cumbria is famous as the county of the English Lake District but it has more to offer than mountain walks. I don’t agree with Alfred Wainwright who said he could not see the point of walking round a mountain when you could climb to the top of it. There are many beautiful walks in the valleys and round the lakes which my wife (and my knees) much prefer over climbing and descending even if they don’t offer much scope for making radio contacts. Less well known, but just as spectacular, are parts of the coastline. One of our favourite outings is to park in the village of Sandwith and go for a walk along the cliffs. This is where we went last Sunday.

Map of the walk (from aprs.fi Google Maps)

The map of the walk shows the path that was tracked on Google Maps APRS, with some additions by me where my position was not tracked.

I was using my VX-8GR with the 5/8 telescopic whip in my rucksack, as shown in the picture on the right. I operate pedestrian portable like this when I don’t expect to encounter too many people who will give me strange looks or think I am a dork. The radio sits in a little mesh pocket on the side of the rucksack which was probably meant to carry a water bottle. The antenna is supported by pushing it through a string loop attached to one of the zips of the main pocket of the rucksack. It is quite stable and does not flex the spring or the mounting at all.

I don’t know what the SWR is like. Possibly it isn’t that good as the radio does not have me holding it to provide a ground plane. Perhaps I should try clipping a 19 inch “tail” to the outer ring of the BNC connector as a counterpoise? But even without it, it worked well. Most of my position beacons were received by MM1BHO across the water in Scotland so I was able to see the track after the walk. I also received some interesting APRS DX, of which more later.

But back to the walk. The weather was glorious, as you can see from the pictures. The temperature was around 20 degrees Celsius with only a slight breeze. The view from the cliffs was spectacular and always reminds me a bit of Cornwall. To think that people pay money to come on holiday to places like this!

We walked for about an hour along the cliffs, stopping now and again to watch some birds through binoculars or just take in the view. This is an important area for wildlife and the Royal Society for the Protection of Birds (RSPB) has set up several places where you can watch them with safety on the edge of the cliffs.

You can walk right along these cliffs as far as St. Bees, where there are people and cafes and ice cream kiosks. But we usually stop at Fleswick Bay, a beach backed by the high cliffs that is always quiet and secluded even in the height of the season because it isn’t possible to reach it by car, it can only be accessed by footpaths. We call it our private beach because we often have it to ourselves.

This Sunday we didn’t go down to the beach because we saw from the clifftops that the tide was in and the sea was right up to the foot of the cliffs. So we had our picnic lunch in one of the RSPB birdwatching areas instead. I made a couple of FM contacts using the VX-8GR, including one with another portable station on a 2,500ft mountain top in Wales. Then we started the walk back.

On the way back I heard the VX-8GR braaping away constantly such as I hadn’t heard since we were in Prague. On my return home I scrolled through the station list and observed that for a couple of minutes between 12:28 and 12:30 UTC I had received beacons from several DX stations including F4EQD-1 and OZ2DXE-2. These beacons had actually been digipeated by a station in south west England but that was still an amazing distance to receive signals on a VHF handheld, even if I didn’t hear them direct.

The glorious weather had also produced fantastic tropospheric propagation which was enjoyed by people in most parts of Europe. I wished I had climbed to the top of a mountain as I would certainly have heard more there than I did down on the west coast and perhaps have worked some real handheld VHF DX. But you can’t predict propagation and it was still a wonderful day’s walk.