HAM Radio – Page 10 – M0AWS Amateur Radio

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

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 …

3 February 20223 February 2022

adi2html v0.5 release

Following on from my original article where I detailed the adi2html Bash script that reads in the WSJT-X log and creates an HTML version of the data so that it can be presented in a palatable format on websites (See my WSJT-X log here), I’ve now released v0.5 for public consumption.

In adi2html v0.5 I’ve added colour to the webpage that is generated to make it easier on the eyes and rewritten the function process_log() so that it uses the column name to identify each field instead of the row position.

By making this change it should cope just fine if the order of the fields is ever altered in the WSJT-X log during its development.

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-v05 Download

2 February 20222 February 2022

Free Great Circle Azimuthal Map

I don’t know about you but, when I’m in the garden erecting antennas I find it hard to work out which way I need to orient the antennas to get the DX I want to work. This is especially true with Delta Loop directional antennas.

I remembered that when I lived in France I had a lovely Great Circle Azimuthal Map on the wall in the radio shack showing the world as viewed from space directly above my QTH in Brittany, this would be ideal for my U.K. QTH too.

Hunting on the internet I soon found the site where I got it from, N6NT has a wonderful little website full of handy little widgets, one of which is the Great Circle Azimuthal Map Generator.

The map is generated in PDF format and can be downloaded and printed locally.

I hope this snippet of info will be of use to some of my readers, it’s certainly very handy for me!

More soon …

1 February 20225 August 2022

Going up in Frequency!

Ever since I got my Class A HAM Radio licence I’ve always been fascinated by the low bands.

160m, 80m and 40m have been my favourite go to bands for chasing DX for many years and I’ve really enjoyed overcoming the challenges that come with such low frequency radio operations. Working DX on 160m I learnt a lot, having a good receiver and a quiet antenna are far more important than having a lot of power. The QRM/QRN on top band often masks the weak DX signals and so designing and building antennas that have a relatively low angle of radiation but, are super quiet on receive is a skill that all top band DXers should embrace.

It’s particularly hard to work DX on 160m in the summer months however, all those DX signals are still there, they’re just masked by the static crashes that plague top band throughout the warmer months.

Discovering the grey line was a real eye opener too. Getting up early in the morning to catch that magic moment that starts just before the sun rises to about an hour afterwards, with DX signals pouring in from VK/ZL before the D layer gets established again. Discovering that on the grey line signals from afar often arrive from a very high angle and can be heard much better on a large horizontal loop near the ground than a large vertical.

As you can tell, I’m passionate about the low bands but, now I’m back in the U.K. and have a U.K. sized garden again those days of large full wave antennas on the low bands are gone and so I must look to pastures new.

To this end I’m going to get onto the higher frequency bands, 20m and upwards. I must admit that I’ve hardly used these bands as I’ve always been so focused on the lower bands.

Currently I have delta loop for 30m up in the garden, this is a great band for us CW and digital guys, it’s a band I really enjoy and so will continue to use it whilst discovering the higher bands.

So I thought I’d start with the 20m band, it’s a band that I’ve heard is really easy to work DX on. Being much quieter than the low bands I’ll give the delta loop antennas a rest and venture into the land of vertical antennas again.

Doing some antenna modelling on EzNEC the End Fed Half Wave (EFHW) antenna has a great radiation pattern with a nice low angle of radiation and even some gain compared to a dipole.

Construction will be easy as the antenna is so small compared to the low band antennas I’ve built in the past.

An EFHW antenna is a relatively simple affair and for 20m it’ll be somewhere around 10.25m tall depending on where on the band I resonate it.

The difficult thing about half wave or any multiple of half wave antenna is that they present a very high impedance at the feed point. Unlike a half wave dipole that is made up of two quarter wave legs that present an almost perfect match to 50 Ohm coax cable (or a 1:1 balun), the EFHW will have a much higher impedance, normally in the range of 2000 Ohms or more. Having such a high impedance also means high voltages at the ends, something to be very aware of especially if you have children or pets in the garden!

Matching to this type of antenna can be done two ways, a simple LC circuit for high impedance feed points or via a 49:1 Unun.

Since I’ve built 1:1 baluns in the past for my delta loop antennas I’ve decided to go the way of the 49:1 Unun.

Simple LC Circuit for High Z matching and a commercially manufactured LDG 49:1 Unun

Looking online for parts to build a 49:1 Unun I stumbled across UK Antennas, they seem to have a wide selection of pre-built EFHW solutions and some very nice looking 49:1 Ununs capable of handling 400w, much more than I will ever throw at it. Contacting Ian the owner of the company via Ebay I found he has a 49:1 Unun in stock that he can ship to me next day so I decided to go ahead and order one rather than source the parts and build it myself.

With the Unun sorted, let’s take a look at the radiation pattern for an EFHW Vertical on the 20m band.

Since I’m looking to do mainly CW and digital modes I’ll be tuning it for the lower end of the band.

Modelling this on EzNEC I’m pleasantly surprised at the radiation pattern of such a simple vertical.

To get a radiation pattern like this on the low bands requires a very large vertical, on 160m we’re talking 80m in height!

On 20m an EFHW is only around 10.25m long, very easy to put up in most U.K. sized gardens using nothing more than an extendable fibre glass pole. The 3D Field Plot shows the lovely deep null in the centre as you’d expect and a great low angle circular radiation pattern.

The elevation 2D field plot really shows the beauty of this antenna.

5.62dBi at 10 Deg and 5.56dBi at 5 Deg, perfect for the long haul DX chaser. The wide deep null in the centre will help attenuate the signals arriving at high angles from the EU that plague us on the East Coast of the UK.

So, it’s time to go find some wire, get cutting and get a fibre glass extendable pole mounted in the garden ready for the arrival of the 49:1 Unun.

More soon ….

UPDATES:

More info on antenna performance here.

Going QRP with the 20m EFHW Vertical and IC-705

Keeping it simple but effective – 20m EFHW Vertical

31 January 202231 January 2022

adi2html v0.3 update

I spent 20min this morning updating the shell script that I wrote to read the wsjtx_log.adi file and create an HTML version of the information for my website. ( Original article here )

The code is a bit shorter now and runs quite a bit faster as I’ve altered the way some of the data is handled.

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_v03 Download