M0AWS – Page 10 – M0AWS Amateur Radio

15 March 202215 March 2022

40m Band NVIS Antenna Experiment

Since setting up the new station at my U.K. QTH I’ve not had any Inter-G contacts. This has mainly been due to the fact that the antennas I’ve currently got in place are all designed for chasing DX and so have far too low a radiation angle to be able to talk to other U.K. stations.

One of the things I do like about radio is the local chatter on the low bands. In the summer months working Inter-G on the low bands is most enjoyable so, I decided to put up a simple Near Vertical Incident Skywave (NVIS) antenna ready for the summer.

Unlike my French QTH, here in Suffolk we only have a tiny garden and so it’s a challenge to get any length of wire up that is anywhere near long enough for the low bands.

A quick measuring of the garden I worked out I could get 30m of wire approximately 3-4m off the ground at best. I’m very aware of my anti-antenna neighbours and so it needs to be as stealthy as possible.

I decided to use some 1.5mm wire that I had in the workshop and utilise the high washing line poles that are already in place to get the wire along the max length of the garden.

With the wire in place and connected to the CG3000 auto remote tuner that I got off of Ebay for a song, ground post and radials connected I found that the antenna tunes up fine on all 3 low bands, perfect!

Tuning up on the 40m band I had an SWR 1:1 anywhere on the band. I could hear a number of strong U.K. stations and a few Dutch and German stations too. Since I’m on the East Coast of the U.K. The Netherlands and Germany aren’t that far away as the crow flies.

Setting the radio onto 40w SSB (First time on SSB in a very long time!) I put out a call. First station to come back was G8VVY, Robin in Malmesbury Wiltshire. Signals weren’t particularly strong and I gave him a 4/4 report and got a 5/5 in return.

Next station was PA3GLK, Dave in The Netherlands. Again signal reports were 5/5 and 5/6 but, perfectly readable.

Next up was G0SXC, Kevin in Lancashire. Signal reports were 5/9 both ways this time, very strong and fully quietening, the high angle radiation was doing its thing!

Last call was ON3PAT, Pat in Belgium. Very strong signals both ways, 5/9++ at a distance of 153 miles. NVIS propagation is working very well. I turned the output down to just 25w and Pat still gave me a 5/9 report.

Later in the day I decided to run some FT8 QSOs on 40m to see how far I could get reliably with no more than 25w. I was hoping that I may just be able to get 1000 miles as an absolute maximum but, be able to work stations at 100 Miles or less with ease.

Map showing NVIS FT8 contacts on the 40m band

As you can see on the map above, 1534 miles was the best achieved, RX3ASQ just east of Moscow. The thing that pleased me most was the number of U.K. stations I could hear with the closest being just 43 miles away. Most European stations were easily worked even with reduced levels of power (10w) and so I’m hoping that this simple end fed NVIS antenna will become my goto antenna for local chatter on the 40m band.

What was very interesting was what I could hear on the antenna, I didn’t expect to hear any DX stations at all however, I was surprised to see stations from Mongolia, Japan and the USA popping up in the WSJT-X window.

Obviously I couldn’t get back to them as my angle of radiation was far too high to get a signal out over those distances but, it just goes to show what can be a heard on a very low long wire.

Map showing stations heard on 40m using NVIS antenna

By the end of the evening to my surprise I had been heard in the USA, I was amazed to see where I’d managed to get into with such a low antenna. The main cluster of stations were in the U.K. and Europe of course which is exactly what I wanted from this antenna.

Stations that heard M0AWS on 40m FT8 using NVIS antenna

So the next test will be on the 80m band, I’m hoping to get similar results on SSB with inter-G stations being easy to work. I doubt I will be able to get anywhere near the 1500 miles I achieved on the 40m band but, I’ll be more than happy with U.K. and EU stations.

More soon …

12 March 202212 March 2022

adi2html v0.6 release

Following on from the adi2html v0.5 release I’ve now added a little more code to include a map of the contacts detailed in the wsjtx_log.adi file so that there is a visual representation of the data included in the webpage. (Map must be generated externally and JPEG/GIF/PNG uploaded to website to be included in the webpage).

See my WSJT-X log here

Just to recap, adi2html generates a HTML webpage from the wsjt x _log.adi file so that the log can be presented in a palatable format on a website.

As before the code can be downloaded using the link below.

If you use my code please consider leaving the footer in place so I get some credit, thanks!

adi2html-v06 Download

5 March 202210 March 2022

Will raising my vertical antenna make it work better?

A question I get asked regularly is:

“Why don’t you mount your 20m EFHW Vertical antenna higher up in the air?
It’ll work much better the higher you get it”.

I have over the years tried raising and lowering my vertical antennas for DXing and found that keeping the base of the antenna and feed point low has advantages over a raised installation. I’ll try and explain this using some 3D and 2D far field plots from the EzNEC antenna modelling software that I use.

Below are the 3D and 2D far field plots as I have it setup at the moment. The 49:1 Unun is at ground level with the base of the antenna also at ground level.

20m EFHW vertical fed at ground level 3D Plot

20m EFHW vertical fed at ground level 2D Plot

Forgetting about the dBi gain figures for the time being and just concentrating on the overall radiation pattern you can see that with the antenna fed at ground level it has a typical circular radiation pattern with a deep null in the centre and a very low angle of maximum radiation. This makes the antenna perfect for DXing and is backed up by the success I’ve had on the 20m band working Australia, Thailand, Indonesia, South America, West Coast USA and Canada. This is exactly what I wanted and I’m extremely happy with it’s performance. I must add that I’m not looking to work European stations with this antenna, I’m only looking for DX stations especially those with very weak signals.

So now let’s take a look at what happens to the radiation pattern when we raise the antenna and the feed point above ground level.

First let’s raise the antenna so that the base and feed point are 3m above ground level.

20m EFHW Vertical with base and feed point 3m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 3m above ground 2D Far Field Plot

Looking at the two far field plots above you can see that with the antenna and feed point raised by 3m we start to get some high angle lobes appearing in the centre of the radiation pattern. The overall maximum radiation is still at a low angle and so this would still be good for DXing but, does have an element of high angle radiation to it now. This will of course mean we’ll start to be able to work stations much closer to us and also be able to hear them better.

Raising the base of the antenna and feed point to 5m above the ground we see that the high angle lobes get even bigger and start to distort the overall radiation pattern of the antenna.

20m EFHW Vertical with base and feed point 5m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 5m above ground 2D Far Field Plot

At 5m above ground the two high angle lobes have increased considerably which will result in more high angle radiation from the antenna. Maximum radiation is still at a low level though and so DXing will still be good with this setup but, from experimentation and experience I know that there are times when closer stations start to affect the ability to pick out the weaker DX stations. This is exactly what I don’t want.

Raising the antenna up even further to 10m above ground we get the following result.

20m EFHW Vertical with base and feed point 10m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 10m above ground 2D Far Field Plot

At 10m above the ground the two high angle lobes shown on the 2D elevation far field plot are now almost as big as the main lobe below it. This means there will be considerable high angle radiation from the antenna which will result in the ability to communicate with stations much closer to your QTH rather than focusing just on the DX stations.

If you’re looking for the best of both worlds then getting your antenna up higher is the way to go, you’ll be able to work stations in the 300-1500 miles range with ease and the DX stations thousands of miles away.

From my experience there is one disadvantage with this in that the closer stations tend to drown out the weaker DX stations reducing the overall DX capability of the antenna and this is why I keep the antenna feed point at ground level. From experimentation and experience gained over the years I’ve found that keeping the antenna base and feed point at ground level gives me a better chance at working the DX than I have if I raise the antenna up higher.

As with everything in life there’s always a compromise!

So it really does depend what you want to use your antenna for. If like me you only want to chase those rare DX stations that are always difficult to get then keep the base of the antenna and feed point low. This will maximise the null in the centre of the radiation pattern and keep interference from “local” stations to a minimum. The draw back to this of course is that you won’t be able to work the closer stations when there is no DX around.

However, if you want the ability to work more “local” stations and the stronger DX stations raise your antenna and feed point up to a more suitable level above ground so that you obtain more high angle radiation from your vertical antenna. Then when there’s no DX around you’ll still be able to chat with the more local stations.

I hope this helps all the people that read my blog understand the choice I have made and why I keep the base of the antenna and feed point at ground level.

More soon …

28 February 202222 July 2023

Venturing onto the 4m Band

The 4m band isn’t a band that I’ve ever used before. The main reason for this is that I’ve never had a radio that had 4m capability built in. Most HF rigs today come with the 6m band but, very few have the 4m band, that is until now.

Having recently purchased a Yaesu FTDX10 I now have access to the 4m band with a max power of 50w. (You do need to reset the radio into UK mode to get the 4m band)

From reading online I understand that the 4m band is very much like the 6m band propagation wise but, with fewer users. Since the 2m and 70cm bands are completely dead in the Woodbridge area I thought that perhaps there might be a few local HAMs on the 4m band.

Now having a transceiver for the band I needed to think about an antenna too.

Searching online I came across an article by G4AQB referencing a 4m band antenna built by Tim, G6TM. Both of these articles incorrectly refer to the antenna design as an EFHW for 4m, it is in fact a Sleeved Dipole or sometimes referred to as an End Fed Vertical Dipole for the 4m band. If it was an EFHW it would have a very high impedance and would need a 49:1 Unun to match it to 50 ohm coax.

Since this antenna is just a dipole it presents an almost perfect impedance match to 50 Ohm coax without the need for any matching circuit.

Working from G4AQB’s build notes as detailed on his blog it’s very quick and easy to cut the coax to the right length, strip part of the outer shield and create the choke using 8 turns of the same coax cable.

Since I wanted to make this a permanent fixture in the garden I decided to make an enclosure for the antenna so that it is weather proof and easy to mount.

Using a mix of 25mm conduit, 50mm plastic tubing, a screw cap and a reducer I put together a very tidy 4m band sleeved dipole vertical antenna.

Home brew 4m sleeved dipole in plastic enclosure

Looking at the photo above you can see I used the 25mm conduit to house the sleeved dipole, I then used a reducer to join the 50mm tube to the 25mm conduit. Drilling two holes in the 50mm tube I brought the coax out and wound it 8 times around the tube to form the choke coil and then passed the coax back into the 50mm tubing so that it continued down to the SO239 socket on the bottom cap. I used some hot glue to hold the choke coil in place.

SO239 mounted in the bottom of the 50m tubing

I strapped the antenna to the top of the washing line post to check the SWR and found it’s a perfect match. With an SWR of 1:1 at the bottom of the band and 1.1:1 at the top of the band.

Overall I’m really pleased with the simple design and build.

I listened to the 4m band for a few hours whilst doing other things and didn’t hear a single soul, I do hope it’s not dead like the 2m band!

More soon …

19 February 202219 February 2022

Falklands Calling …

When I lived in France (F5VKM) I was totally focused on the low bands. I spent years trying to get the Falkland Islands on 160m. Now living in the UK with a typical small garden I no longer have the luxury of big antennas. Currently I’ve just got my EFHW Vertical for 20m at the end of the garden.

Today I heard the Falkland Islands on 20m for the first time since setting up the new station, I was amazed to say the least.

I decided to give the two stations a call, didn’t get an answer from VP8ADR but, VP8VK then popped up and I snuck in and got a quick QSO with just 25w.

Working DX is so much easier on 20m than it is on 160m, I’m amazed!

-23dB is very close to the limit for FT8 but, it was enough to get a complete QSO and the Falklands in the log.

I also got VK6AS on 20m FT8 today, again with just 25w. This EFHW Vertical for 20m really is an excellent DX antenna, it’s perfect for the small garden too!

More soon …

11 February 2022

Convert your RUMLogng radio logs to HTML

I’ve started using RUMLogng for logging on my MacBook Pro as it seems to be the most common logbook to use on the Apple Mac platform. I must admit that I’m not sure if I’ll carry on using it going forward as I’m not overly enamoured by it but, for the time being it’s all I have.

To get my logs on the blog I’ve written a small BASH shell script that reads the exported ADIF file from RUMLogng and creates a log in HTML format for each different mode.

You can see the output of the BASH script by selecting a log from the Logs menu at the top of this page.

If you want to be able to add your log to your own website then I’ve made the script available for download below.

Currently I’ve only tested the script with the few different modes that I have log entries for but, it should work for all modes. If you find any issues please contact me with all the details and I’ll look into resolving any problems.

As always, if you use my code to generate webpages on your website please consider leaving the footer in place so I get some credit, thanks!

RUMLog2html-v09 Download

10 February 202211 February 2022

20m EFHW Vertical sunset

8 February 2022

FTDX10, Apple Computers and the USB Audio Chain

One of the things I’ve had issues with ever since purchasing the Yaesu FTDX10 transceiver is control of the audio chain via the USB connection on the rear of the radio.

The output from the radio into my Macbook Pro is just too high, WSJT-X is constantly pushed beyond the green zone and often into the red zone when monitoring FT8 signals with the AGC off. The only way to cure this is to keep the AGC on Auto which sometimes results in not hearing the very weak DX stations due to the AGC not reacting fast enough. Putting the AGC on fast causes the red line to be hit far too often once more.

Sadly, the USB Audio Codec doesn’t provide any volume adjustment on audio coming from the radio into the MacBook Pro thus, it’s just full volume all the way. This is a flaw in the codec design and really does need to be resolved long term.

Looking at the audio going the other way, that is from the MacBook Pro into the radio via the USB port fortunately there are gain controls available both on the MacBook Pro and on the radio itself.

Ever since venturing into the world of WSJT-X & FT8/4 I’ve had an issue with only being able to move the PWR slider in the WSJT-X up to the first marker at the bottom of the screen, anymore and the ALC on the radio goes off the scale instantly!

So yesterday I decided to investigate the audio chain into the radio more thoroughly and see what could be done about the levels.

Looking at the radio manual I found that there is an RPORT GAIN setting in the menu system that can be used to alter the amount of gain applied to the incoming audio signal on the USB port in the radio.

As detailed in the manual, the default setting for this is 50 in a range of 0 to 100. So that’s a 50% increase in gain applied to the incoming audio at the radio end, that’s quite a boost! (The gain is applied both in SSB and Data Modes)

I decided to experiment reducing this figure to see if it gave me greater control over the audio output from WSJT-X via the PWR control. This did indeed help however, there was still too much audio coming into the radio from the MacBook Pro and so I needed to look further along the audio chain.

Moving back onto the MacBook I opened the Midi App and took at look at the Output controls for the USB Audio Codec, sure enough this was set to max for both channels, not good.

Reducing the levels in the midi app started to make much more of a difference, I could now raise the audio level using the PWR control in WSJT-X without things immediately going wild and could now control the levels with a far greater level of granularity than ever before.

After much tinkering I eventually found the levels whereby I could drive the rig to the selected output power (20w) without the ALC going off the scale and the signal becoming horribly distorted, there was calm in my audio chain once more.

So what settings did I settle on?

On the radio itself I wound down the RPORT GAIN setting from 50 to 20, this reduced the amount of gain applied to the audio coming in on the USB port considerably and helped to tidy up the FT8 signal.

FTDX10 RPORT GAIN Setting reduced from 50 to 20

It’s great that there is the facility on the radio to reduce the gain on the inbound audio signal, if only Yaesu would do the same for the outbound audio level.

Next, on my MacBook Pro via the Midi app I reduced the output level on the USB Audio Codec from the default maximum down to 0.494 (-19). This stops the audio level from being too high going into the radio and removes all distortion from the resulting signal.

Midi App on Macbook Pro showing reduced audio output

Once these small changes have been made it becomes necessary to raise the PWR level in the WSJT-X app to roughly the centre position. At this point the radio gets a clean, distortion free audio input whilst driving the radio to the full 20w output with no movement on the ALC whatsoever.

I found I could move anywhere on the frequency spectrum on FT8 without any of the levels changing and with the ALC not moving whilst the radio delivered the full 20w output.

I also checked FT4 mode as it is an MFSK mode to see if these settings worked for it too and I’m glad to say it worked perfectly! (I also found I really liked FT4!)

WSJT-X with the PWR setting at roughly 50%

Altering the PWR level in WSJT-X doesn’t have the huge effect it had before and now it’s very easy to adjust the level without the ALC going off the scale in an instant.

It took me about an hour or so to get this just right but, it was well worth the time invested.

I hope this is of use to other Apple Mac computer users in the HAM community.

More soon …

5 February 202212 March 2022

Simple EFHW vertical on 20m works great!

I completed the fine tuning of the 20m EFHW Vertical today, I got the SWR down to 1:1 at 14.10 Mhz. This gives me a perfect match for the CW and digital section of the band with the SSB part of the band not exceeding 1.4:1 at 14.350.

I ended up removing 34.5cm of wire from the original antenna length to get the resonance where I wanted it. This was caused mainly by the extra inductance added into the circuit by the 49:1 Unun. This is to be expected and perfectly normal when feeding an antenna via an impedance matching transformer.

I bolted the 49:1 Unun directly to the earth rod, this way it’s got a solid earth connected directly to it to keep the resistance to a minimum. (The metal mounting plate is also the earth termination point).

I spent some time today chasing the DX on the 20m band using the FT8 digital mode.

The fun started with VK2LAW in Sydney Australia, followed by E25ETT in Thailand, KP4CAR in Puerto Rico, 9G5AR in Accra Ghana and The Sahrawi Amateur Radio Club station S01WS in Western Sahara. A nice mix of stations dotted around the world.

PSKReporter map showing all the stations that I heard on 20m today

I like to keep an eye on the PSKReporter site whilst on air to see what I’m hearing. As you can see I heard stations from the West Coast USA right across to New South Wales in Australia and down south as far as Brazil. The 20m EFHW Vertical antenna and Yaesu FTDX10 radio combination really does have good ears

As for being heard, well it’s a similar story, below is a map showing all the stations that heard me as reported on the PSKReporter website.

One again, great global coverage from the antenna and transceiver combo with only 20w being used for most contacts. (25w used to break some of the pileups!)

Overall I’m really pleased with the performance of the antenna, for such a simple design it works exceedingly well. One huge advantage of a half wave over a quarter wave antenna is that the point of max current is 50% along the antenna’s length, on the 20m band EFHW Vertical this puts it some 5m above the ground lowering the angle of take off and making it a great DX antenna.

If you’ve not got a lot of space but, want to work the DX on 20m then I highly recommend you give one a try, I’m sure you’ll be amazed at how well it performs.

Can’t wait to get a 40m EFHW Inverted L up next!

Information as to why it’s best to keep the feed point at ground level for this antenna is here.

More soon …

4 February 202212 March 2022

20m EFHW Vertical + 49:1 Unun = DX

My 49:1 Unun arrived from UK Antennas today, lost no time getting it into the garden and connected to the 20m EFHW Vertical antenna.

I’m really pleased with the 49:1 Unun, really nicely put together and packaged professionally, great to get such a nice British made product!

Connecting the Unun up to the antenna I found that it added a little extra inductance I hadn’t planned for and so I needed to shorten the vertical wire a little to compensate.

It took 3 snips of wire to get the antenna resonant in the 20m band again, with an SWR of 1.3:1 and the sun starting to set I decided that was fine for now and I’ll fine tune it tomorrow in the daylight. (See end of article for update)

Heading into the shack the 20m band was buzzing, lots of big signals and DX. I switched on to the 10m band and checked the SWR there, 1:1 across most of the band, perfect!

I then went on to check the 15m band, now I wasn’t expecting a match as it shouldn’t resonate there but, I found a 2:1 SWR across the band, weird!

So back on 20m, I plugged in the MacBook Pro and started WSJT-X in FT8 mode to see what was around.

20m EFHW Vertical at the end of the garden

First contact was into Canada, VE2FVV with a -10 report both ways and 2962 miles, not bad for 20w.

I then worked a flurry of stations from the USA but, the one I was really pleased with was PP1WW in Brazil. 5610 Miles using just 20w, this EFHW vertical really does has a lovely low angle of radiation.

PP1WW was the last station worked as it was dark by this time and the band closed. It was interesting to watch the PSKReporter site to see where I was being heard.

As you can see from the PSKReporter screenshot above, I was heard pretty much all over the world. I saw a number of VK stations in Australia pop up on FT8 but, never managed to get an answer back from any of them even though they reported hearing me on the PSKReporter site.

I was also pleased with the number of stations that I heard, once again good global coverage.

Band conditions are generally poor at the moment and we’re in a bad part of the 11 year sunspot cycle. Hopefully in the coming years propagation will improve and we’ll be able to work the world on just a couple of milliwatts!

I also tuned up onto the 10m band and heard quite a few FT8 stations on there, I was surprised as I wasn’t expecting the band to be open.

So tomorrow, I need to fine tune the antenna for the 20m band and get the SWR down to 1:1, hopefully this won’t affect the 10m band tuning too much.

Once the 12m Spiderpoles are back in stock I’ll get one ordered and build the 40m EFHW Inverted L that I’ve designed, I’m hoping it will open up the 40m/20/15/10m bands for some DXing over the summer months.

UPDATE: I ended up snipping off a total of 34.5cm of wire to get the SWR 1:1 at 14.100Mhz. This makes the entire 20m band useable with the SWR less than 1.5:1 at each end of the band. 2nd contact after trimming the wire was VK2LAW at 10454 Miles using just 25w of power.

Information as to why it’s best to keep the feed point at ground level for this antenna is here.

More soon …