CQ DE VK7BEN

Just another Amateur Radio Operator

More Experiments with EFHW Antennas – Part 2

EFHW Match Unit

It’s been a couple of years now since my first post on EFHW Antennas. Notably since then I have acquired a Mini 600 Analyser. Armed with technology it was time to revisit this “no-tune” portable antenna. What followed was 3 months of confusion, learning and experimentation.

Before I go any further I would sincerely like to thank David VK3IL for his patience and assistance over the last 2 weeks in helping me troubleshoot my issues and teach me a bit more about what I was doing along the way.

It all started when I thought it would be a good idea to re-test the end-fed antenna now I have a new analyser as I was preparing ready-to-assemble kits for my local radio club and didn’t want to see people ending up with an antenna that didn’t work as described. To my dismay, the antenna definitely was not working as originally described.

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Hands on with the Mini 600 Antenna Analyser

Picture of Mini 600 Analyzer

For a long time now I have had a home-brew antenna analyser based on the VK5JST design. While this has served me OK, the accuracy of the 6m frequency was questionable, as the notes on the side of the tool suggested, and I was really needing something for VHF and UHF with my new interest in satellite and antenna construction.

I had in the past drooled over the Youkits FG-01A, but this again was HF +6m only, and the costs of an MFJ analyser were just wildly out of my range taking into account USD – AUD exchange rates. However we’ve once again seen electronics commoditised over the last few years, and this has led to inexpensive alternatives becoming available. It didn’t take long for the Mini 600, based on the EU1KY design to catch my attention, ticking all the boxes.

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A V/U Handheld Moxon Antenna for Satellites

The Completed MoxonAs per my last post, I have been getting pretty excited about working satellites. However relying on the little ‘rubber duck’ antenna that came with the IC-T90A hand held does limit the range in a way that I could only really work the satellites at high elevation angles. With costs of commercial V/U antennas for satellite work usually over $200 AUD, it was time to build my own.

I did have some constraints around the antenna design:

  • It had to cost under $50 to make.
  • No speciality materials required – I could either readily purchase from a shop, or I already had materials on hand.
  • It had to be made using tools I had on hand.

The last point ruled out making a crossed yagi antenna to my standards as it would require a drill press to successfully fabricate (I am bad at drilling square!)

In the end a quick google found me looking at making a Moxon designed by LY3LP and modified by M1GEO, but I really wanted to get some close ups of some of the more important parts of the build. What follows is an abbreviated build guide with photos. In all, it took less than 2 hours to construct.

Update 22/12/2018 2.15pm – Yep, this antenna is a winner – here is the audio from the AO-91 pass @ 2018-12-22 1342 AEDT. Big improvement – action starts at around 2mins in.

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My First Satellite Contacts with AO-92

I’d only ever heard it was possible to work amateur satellites with hand held radios, and all the accompanying photos usually involved waving around a modest sized handheld Yagi. All that changed when I saw a posted a video posted on the Central Coast Amateur Radio Club Facebook page showing AO-92 being worked with Yaesu VX8 handheld with an after-market whip antenna.

A quick check of the passes saw really favourable conditions to work AO-92 as it passed overhead on Friday 14th December 2018 from around 11.22pm local time.

I quickly set up the frequencies in my IC-T90A, gave a couple of friends a heads up to listen for me and waited.

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WWFF Afternoon – Mount Field National Park VKFF-0347


Activation from Wombat Moor in Mt Field NP.

We’ve had some fantastic weather down in VK7 recently, and today I decided to take full advantage of it with a solo trip to Mt Field National Park. This was mainly supposed to be a photography mission today, with the FT-817 thrown in “just in case”, however arriving at the park and seeing maybe around 100 cars I decided to put the photography on hold until later in the afternoon and headed up to Wombat Moore.

The linked dipole was in the car today, as fun as the EFHW is, the Dipole is much easier to set up as free standing.

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RD Contest 2017

RTTY QSOs during 2017 RD Contest

RTTY QSOs during 2017 RD Contest

The 2017 RD Contest was over the weekend of August 12-13 and I was keen to participate this year, having been unable to participate last year due to my involvement in the Festival of Bright Ideas. With Tasmania winning the state vs state competition, I was keen to do my bit to defend that title.

With the waning solar cycle leading to pretty poor propagation conditions in my near NVIS antenna setup, my focus had been working local stations on VHF and higher bands. Critically, I was now in a position to take advantage of the allowed RTTY digital mode, which was worth double points on 144Mhz and 430Mhz, 4 points on the 23cm band, and a triple multiplier between 1am and 6am meaning there was up to 12 points per contact on offer!

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A 3D Case for the TNC-Pi

TNC-Pi Printed Enclosure

TNC-Pi Printed Enclosure

In my last post, one of the things I mentioned was that I built a TNC-Pi shield for my Raspberry Pi, that allows be take part in packet radio. One of the things I didn’t like so much was that I had nothing to put it in to protect the circuits from dust or a misplaced screwdriver shorting out the board.

I was therefore pretty happy to receive as a birthday gift a 3D Printed enclosure designed to hold the Raspberry Pi and TNC from Scott VK7LXX. I’d pointed out the design about a week earlier when looking around, but lacked access to a 3D printer and spare time needed to print.

As you can see in the image to the left and above, it makes quite a comfortable fit. I used a bit of foam to sandwich between the Pi-TNC and the USB ports of the Pi just to prevent any contact of soldered joints with the metal casing around the USB connectors.

Scott tells me this printing was done at a “coarse” level, to speed up the print process and took around 3 hours to print. Those who are eagle eyed will notice that cases bottom is slightly rounded due to an imperfection in the print process – I’m not worried by this because the objective is to protect whats inside, not necessarily be pretty.

3-6 months ago, I was mocking the idea of needing a 3D printer, but I’m not laughing now. I can definitely see myself using a 3D printer to make custom parts in the shack!

Where the Heck is VK7BEN?

It’s been quite a while between posts, and in fact this is only my second post since January. It’s not because I have been slacking off though. So I’ll try and give a bit of an update as to whats been going on.

Pa posing for the camera, Huon River

A couple of weeks after my last post, my Grandfather died ūüôĀ It was for reasons known about to family, but it always happens sooner than you would like and the loss has been immense. I was particularly close to my grandfather and even 3 months later the thought that I can no longer see him is very raw and hard to deal with.

“Pa’s” influence on me has certainly be that of love for Tasmania’s vast wilderness. When I am not playing with amateur radio, I love taking photography of a wild Tasmania, of which you can see many of these photos over on Flickr.

Pa also encouraged my technical abilities and was fascinated by the things I was doing in the radio space, from who I contacted via DX, to how light could be modulated with audio along to being able to broadcast Television. As I said, I’ll miss my conversations with him.

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Giving a FSQ! Instant Messaging on Air

FSQ in fldigi

It seems I don’t get to play on air as much as I would like, but the other day I discovered a video by Kevin KB9RLW¬†talking about this digital chat mode called FSQ. I shared the link with guys in the VK7 Online Chat Room¬†and before I knew it, there were 3-4 people getting set up to use this mode.

Fast Simple QSO (FSQ) has been around since 2014 and is developed by two New Zealanders –¬†Con Wassilieff ZL2AFP & Murray Greenman ZL1BPU. It has some rather interesting characteristics about it such as weak signal capabilities, the ability to send files and pictures and also that commands can be sent ¬†as triggers to remote devices. ¬†The latter is very interesting for propagation reports – being able to send a command out and then have reports given back about your SNR amongst other uses.

Anyway, early days for my experimentation with this mode and I am sure you will hear more from me about it soon!

 

SOTA Activations VK7/SC-001 & VK7/SC-045

Today I finally got around to activating my first summit – Mt Wellington VK7/SC-001.

Given I had a “very long weekend” for Australia Day, I was determined that I would get some portable radio operations in over the weekend. A work colleague Richard, VK7FLCS, had also expressed an interest in seeing how easy portable operation was so the date was set for early afternoon to activate Mt Wellington, and then Mount Rumney if time permitted.

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