Experiments with an End Fed Half Wave Antenna

Portable Setup, Mount Direction
Portable on Mount Direction

I went away to the Tasmania’s West Coast in October 2016 and had hoped to work some stations. For radio, the trip was a bit of a disaster with the place we were staying having lots of solar inverter noise. The other thing was that it was very tedious to use a linked dipole in the location I was in. Since that day I had resolved that I would try and end-fed antenna and see how that goes.

The End Fed Half Wave (EFHW) antenna is popular with many QRP Portable stations, particularly for activities such as SOTA or WWFF. The big drawback of the end-fed is the high impedances they have, which means that you need to carry some sort of Antenna tuner to match the impedance with the radio. The thought of lugging around an antenna tuner and then having to retune every time I switched frequency was less than appealing though.

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In the Beginning…

Happy 2017 Everyone!

The New Year is about beginnings for many, so it seems as good a time as any to share my story about how I started in amateur radio.

I was introduced to Amateur Radio in the Early 1990s by Charles Payne, VK7PP. I met Charles when I was tracing back the history of my Heron Sailing Dinghy, Sobraon, at the time and which he and his son Andrew built in the 1970s. When he took me up to his study to find some photos, he pointed out all his amateur radio gear and showed me how to make contact. After that I visited several times over the next 2-3 years to explore amateur radio after school, before leaving for college meant that it was too difficult to visit.

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2016 Oceania SSB DX Contest

Over the weekend, the 2016 Oceania DX Contest was held. This was my first contest for the season, having missed this years RD Contest due to other commitments.

This year was definitely hard going compared to last year, with band propagation conditions truly terrible throughout the contest and then suffering the static crashes from a lightning storm occurring on the SA/NSW/VIC border later on Sunday afternoon. I wasn’t being particularly serious about the event this year, and therefore much of the time was spent in “search and pounce” mode making the initial contacts and then after the initial flurry, going off to do something else and returning to the radio every half hour or so to spin the dial and listen for any new signals.

And new signals were very few and far between, with only 9 contacts logged in the last 12 hours of the contest, with most bands only answering with the sound of the noise floor up until the last 3 hours of the contest on Sunday.

In the end I managed 42 contacts over the 24 hours of the contest, with the band split below:

Band QSOs
1.8 2
3.5 14
7 16
14 10

In comparison, this is around half the contacts from my 2015 contest effort. Notably last year there was much more activity on 20m (39 contacts) than this year, and 15m saw some contacts where this year there was none.

During the contest, I think my highlights would have been working 2 stations on 160m – it’s very rare for me to work anything at all on “top band”, along with being able to exchange contacts with stations I knew such as IK4GRO and VK5PAS (Hi Paul!).

Well the next big contest is CQWW SSB, which will be “The Big One”. Looking forward to it.

Festival of Bright Ideas 2016

REAST FOBI Stand 2016

I recently had the pleasure of helping my radio club host a stand as part of the Festival of Bright Ideas in Hobart, held has part of National Science Week. This has been one of the first public events that the club has been involved with for some time, and has it turned out, it was a great success!

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Bluetooth Rig Control for $10!

HC-05 Interface Board
The Bluetooth Dongle. Read below for details

If it’s one thing that continually amazes me is the impact Arduino & IoT are having on Amateur Radio. Things that were once complex pieces of electronics with a complex price tag are now commoditised and available for pennies.

When I first started, a CAT rig control interface could cost up to $200, particularly if on-brand. Taking a look on eBay now, you can find a heap of these Bluetooth Dongles that plug into the back of my FT-817 for generally around $12!

Unfortunately for me, the one that arrived is dead on arrival. It did give me an opportunity to pop the cover and see what is inside. there is not a lot to it at all! To the right of the LED in the picture is basically an AMS1117 3.3V regulated power circuit base, with an HC-05 Serial TTL to Bluetooth Module soldered on as a daughterboard. With only 5 pins in use – +ve, gnd, rx, tx, and LED state, very little needs to be done with these units other than connecting the cables at the right places!

My testing of this unit found that the HC05 board is defective. I have confirmed all power is going to the right places, and it is correctly wired, but unfortunately the unit does not broadcast a bluetooth device ID. This is the big catch when buying from eBay – you get what you pay for! lucky for me the seller is willing to send a replacement unit.

I think however I will eventually purchase one of the units made by K6VHF┬á(His eBay store here). Its ridiculously more expensive, but I will get a unit that has been assembled and tested properly by someone familiar with the radios – and given I spent about an hour of my time today troubleshooting the defective one, with unknown quality of the replacement, that may be money well spent.

I’ll give an update when I have a working adaptor!

A Quick Activation of Trevallyn Recreation Nature Area VKFF-1156

 

IMG_2017

I had a day trip to Launceston today to assist a new amateur radio operator get on air with his HF rig. I decided that if I has some spare time left over we could stop by the nearby Trevallyn Recreation Nature Reserve and work a few contacts from it.

VKFF-1156 is again somewhere pretty easy to get to, being part of the tourist trail in Launceston and giving access to Lake Trevallyn and the hydro power dam. Access is via sealed road and I ended up setting up of a flat area a couple of hundred metres up from the boat ramp.

This also gave me an opportunity to try my new portable station. I have done away the the aluminium mast and Icom 706 as my go-to configuration and now have a squid pole, linked dipole and FT-817 QRP radio for portable operation. It all sounds suspiciously like I might be getting into SOTA soon! I will probably boost the in-car  configuration with a QRP amplifier.

IMG_2018

This also gave me the opportunity to try a tweak to my logging set up by use Fast Log Entry to for WWFF. For those of you who are observant, yes that is an iPad, and yes that does look a lot like Windows! What I actually have is a small 7″Pendo Pad running Windows 8.1 (These can’t be bought any more) that I connect to iPad hotspot with, and then remote desktop to the Pendo tablet to run FLE. Its all a bit complicated, but FLE is the simplest way to log WWFF contacts effectively in an ADIF format.
IMG_2019

I’d love to say I jung around and got the 44 contacts, however the Tasmanian sun is very harsh and I was very quickly getting burnt. Also, the bands were incredibly open from that location – I could not find a free frequency to call on on the 20m band, with 40m being equally full. In the end I had to make do with just 3-4 contacts and the knowledge that I really need to go back again and do it properly.

Building A linked Dipole

IMG_1989It’s been a little while since I have posted, and its not because I haven’t been doing anything. I’ve been getting my portable station even more portable that before. Ov er the past 3 weeks where I have had a spare evening I have been putting together a new portable station that is even more lightweight than the previous setup featured in my post on Peter Murrell Reserve. Key to this has been producing a linked dipole.

Linked dipoles provide the benefit of creating a single-wire antenna that is resonant on multiple bands without a tuner by “linking” together lengths of wire with clips. While there is no limit on how many links you make, it may not be practical to make the dipole suit everything between 1.8 and 450 Mhz.

I ended up going for a 5 band antenna – 6m, 10m, 15m, 20m, 40m.

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Activating Peter Murrell Reserve VKFF-1146

QRV VKFF-1146As much as I am a fan of Summits On The Air (SOTA), activating a summit requires a level of portability that I am yet to obtain as well as a level of fitness that I am yet to obtain too, which is why I got pretty excited when I discovered the World Wide Flora and Fauna (WWFF) Program.

Recently there have been a number of additions made to the Database for VK7, which originally was national parks only. The inclusion of a number of new conservation reserves meant that I was able to activate Peter Murrell Reserve which was only 30 minutes away as opposed to a significant 2 hour drive to the nearest national park. It also helped that the carpark fell just within the VKFF boundary.

Being such a glorious day weather wise I made the spur of the moment decision to activate the park.

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Stuffing the Smoke Back In!

Loads

This post will end the saga where I let the magic smoke out of a somewhat expensive commercial antenna.

Today a package arrived in the mail from china which greatly excited me. In it was 100x 10k ohm 3 Watt carbon film resistors from eBay, costing around $8 including delivery. with these, some Veroboard and a little bit of patience I was rebuilding the resistive loads in the antenna. one of the old loads is on the left and the new home brew one is on the right. The damaged resistors are marked as 10k ohm, but measuring them with a multimeter gave a reading of 1.1k ohm.

Read moreStuffing the Smoke Back In!