Radio

After having some luck with simply putting scrap metal into the air as a vertical antenna at 14MHz, we decided to try and do things properly. A trip to the local hardware store has proven quite useful for sourcing antenna elements. 3 metre lengths of 10mm aluminium tubing came out to only AU$8 or so. Of course, it aluminium tubing can be sourced more cheaply (especially as scrap), but this was more convenient for simple experiments.

It seemed like the biggest drawback to our previous verticals was the height above ground. Our copper gas pipe experiment had the base of the antenna only 3 metres above the ground, with the radials lazily laying on nearby objects.

This time, we decided to utilise our EMDRC 9 metre collapsable mast. We had decided to use PVC water piping as the mount system. Unfortunately we never bothered to collapse the mast and measure the outer diameter of the upper section, and ended up buying pipe which was too wide, and possibly too thin-walled. With a bit of persitance and trying again to get the holes to match up with the screws (how do you properly measure straight lines on a cylinder?), we had about 5 metres of aluminium in three telescoping segments on PVC. For the radial system we used self tapping screws to attach a 5cm wide alu strap around the PVC below the vertical element, with one larger hole for attaching an SO-239 socket. The centre conductor of the SO-239 is attached to a short jump lead with a terminal plug around the mount screw at the base of the vertial element.

20m vertical test on ground

Detail of vertical element and radial mount

Mounted vertical ready to raise. Dipole mount for 80/40 below.

Raising 9metre mast with 20m vertical

It began to get dark by the time everything was constructed and roughly tuned. Turns out we had mixed up some of the radials and guy wires, which wrapped around each other at the top. Not expecting good results the first on the first try, I was surprised to find it gave little to no reactive loading at resonance, which was around 13.9MHz. The resistive load of the antenna was much higher than expected, at nearly 200 Ohms. I had read the angle of radials to vertical element can change the Zo of the system, but had no time to try at the time.

Coming back to it, and getting the radials as close to 45 degrees from vertical as possible gave good results. We were able to get the Zo down to a good-enough match of 60 Ohms across the lower section of the 20 metre amateur band. the 2:1 bandwidth was across any usable frequency for amateur use.

The 1964 ARRL Antenna Handbook gives ideas for multi-band verticals containing multiple resonant vertical elements with 4 resonant radials for each band. This PVC mounted system may lend itself well to this setup, just in time for the growing 10 metre openings.

de VK3GNU. 73

Tags: antennas, musings, tech by Hannah
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Over the past months, Ivy and I have been trying to catch those DX stations. In the current time of solar minimum, it has been hard to return to the calls with our meager 100W. And, not being able to afford stacked monobanders and a leenyer, we’ve decided to try and improve what we can, which is antennas.

The first choice was to install HF verticals for different bands. Since they are relatively easy to construct with just wire, and have a low take-off angle of radiation, we decided to go for it.

Wonky 20 metre vertical

First was a 20 metre vertical. Scrounging around for parts, we came across a sad piece of copper pipe that had been left outside for some months. After straightening it out the best we could, it measured just over 4 metres in length. My understanding of antennas isn’t all that great, but I do understand velocity factor. Copper pipe is said to have a VF of 0.86 or so. Given our poor copper was in an advanced state of oxidation, I figured the VF would be lower.

Oh well, might as well just load it up and see. After sanding off the corrosion on the bottom and attaching a strapping wire via a clamp, it seemed to have OK continuity. Then we decided to try 4 radials of scrap wire, each at 1/4 of a wavelength. The vertical was then installed on the roof with surprising results. Though we could not get the SWR down below 1.7 or so, it happened to have this dip at ~14100kHz. This antenna performed quite well, considering it cost us the grand total of naught

With the success of 20 metres, we decided to again try, this time on 40 metres. Around this time we decided to buy one of the EMDRC 9 metre aluminium masts. While it’s a tad short for the 10 metre tall 1/4 wavelength vertical at 7MHz, we came up with a clever solution to extendorise the mast. Using a 3 metre long bit of orange electrical conduit, we slid our extender into the top of the mast section. The whole thing flopped right over to one side. But hey, the radiating element can’t be too close to the metal mast anyway, else it will couple and cause a distorted radiating pattern and possibly effect impedence. The bendy conduit put the vertical about a metre and a half to one side of the mast, and the bottom of the 10 metre radiating wire ended up just above the ground. More 1/4 wavelength radials, and we were on the air. This one, though, was able to be tuned by way of changing the length. We managed to bring the SWR down to about 1.2:1 at ~7200kHz.

Results with the 40 metre vertical weren’t as drastically increased as with 20 metres. We got only slightly better (often only 1 S-unit) signals on the vertical compared to the dipole. The radiation pattern for transmit seemed to be pretty similar to the dipoles as well. It was useful as an antenna for local contacts, but we still couldn’t get those DX stations to hear us.

We’ve since given up on the verticals, in favour of a ZL-Special. There will be more to come.

73, Hannah

Tags: antennas, dx, tech by Hannah
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After a few hours of trying, I was finally able to have a QSO with someone via PSK31! The levels and connectors are a bit finicky, but using W1HKJ’s FlDigi in GNU/Linux works a treat. I spoke with Andrew, VK5EX, in Adelaide with a report of 599 both directions. He was able to give me a few pointers with levels, noticing I was emitting a few more sidebands than I should have been. I really like the idea of PSK31, as it can get through when voice is really hard.

CQ CQ CQ de VK3GNU VK3GNU VK3GNU
CQ CQ CQ de VK3GNU VK3GNU VK3GNU pse k
… ??? de VK5EX VK5EX DE VK3GNU VK3GNU PSE K VK3GNU VK3GNU VK3GNU de VK5EX VK5EX VK5EX pse kn VK5EX DE VK3GNU VY GUD TO HEAR YOU. 1ST PSK QSO 1ST QSO. HOW COPY? 599 IN MELBOURNE NAME HERE IS HANNAH. HANNAH KN… VK3GNU de VK5EX

Hi Hannah, ur report is 599 599 my name is Andrew , Andrew
and Im located in Adelaide South Australia , Adelaide South Australia.
My locator is PF95HA , PF95HA … so BTU Hannah, VK3GNU de VK5EX k VK5EX DE VK3GNU. QSL 599 ES PF95HA. QTH HERE IS QF22. QF22. QF22. USING ICOM 706 ICOM 706 AND 100WATTS. BTU VK5EX VK3GNU… VK3GNU de VK5EX

All ok Hannah, here are my station details. Im using a Kenwood, TS2000 running 25 Watts
with a RigExpert Standard USB Sound card interface into a OCF Dipole @ 30ft.
The software Im using is HRD + DM780 v4.0 SP4. .. Im noticing that your signal has many sidebands and is probably a bit too wide for this mode .. have you adjusted your radio for no ALC . ?? .. maybe knock your power down to 50 watts or less as well … … so BTU Hannah, VK3GNU de VK5EX k VK5EX DE VK3GNU TU VY MUCH FOR THE REPORT. NEW TO PSK SO STILL LEARNING. HAVE REDUCED GAIN AND POWER OUTPUT. USING ONLY A LAPTOP RUNNING LINUX AND FLDIGI USING AUDIO CABLES AND VOX CIRCUIT ON ICOM 706. ANTENNA HERE IS DROOPY DIPOLE AT 4 METERS. JUST GOT LICENSED A FEW WEEKS AGO AND MADE QSO WITH RUSSIA, UE6MAC/0 LAST NIGHT. ENJOYING RADIO VY MUCH. GOOD TO SEE YOU ON THE AIR, AND IT IS ALMOST TIME FOR ME TO PREPARE TEA. THANK YOU VY MUCH FOR QSO AND YOUR SIG IS FINE BUSINESS HERE. BEST 73 AND WAITING FOR YOUR LAST. BTU VK5EX DE VK3GNUe..&Tz3GNU de VK5EX .. al ok Hannah .. ok on the setup there .. It is great to see more lunux / fldigi users . I think that Linux will become the altimate operating system for hams as time goes on. .. Yes very good to work you for the first time , and Im sure you will gain a lot of enjoyment from the hobby. Ive been licenced since 1982 , and I still cant get bored with the hobby .. hi hi .. also notice that your still generating some sidebands there. yre o robably need to knock your mic gain down even further so as to not to ovverdrive the radio .. PSK31 is a bit temprimental with regards to drive levels .. really its probably better to underdrive than ovverdrive things .. also make sure that you have any mic processors etc etc .. tutrned off as well .. so anyway Im sure you’ll be able to adjust a few things there to get your station operating perfecntly, Takes a bit of time a guess , like all things , .. ok then .. well Ill leave you with it , go go and organise tea. I think we are going out for Itallian tonight I believe. .. only 3.30 ish here in adelaide ,, sm we have still got a couple of hours befre we decide where we’re going .. ok then btu for a final and then we’ll go clear … so BTU Hannah, VK3GNU de VK5EX k COPY FIND HERE VK5EX DE VK3GNU TURNED THE MIC GAIN DOWN EVEN MORE SO HOPE IT WORKS BETTER IN THE FUTURE. THANKS AGAIN FOR THE FIRST PSK QSO, HOPE TO TALK TO YOU SOON. BEST 73 ES 88. ENJOY ITALIAN. VK5EX DE VK3GNU CLEARonA VK3GNU de VK5EX 73 Hannah and thanks for this BPSK-31 QSO on 40m, good DX in 200
VK3GNU de VK5EX sk

Tags: digi, tech by Hannah
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Well, we finally did it. Yesterday Ivy and I bought a bunch of radio gear so we could get on the air.

• Icom 706 mark IIg radio
• Icom PS-300 power supply
• LDG AT-7000 automatic antenna tuner
• Diamond X50 V/UHF antenna
• Diamond SRH-771 HT Whip

We got most the gear from StrictlyHam. Ross didn’t have the tuner so we went to visit Dave from TT Systems. He was really nice and showed us his high power remote antenna tuner project, and even fitted off some coax for us. We couldn’t wait to get to Ivy’s parents’ to start operating. What perfect timing, too. This weekend was both the Lighthouse weekend and the Australian Rememberance Day contest. So after plugging everything in, we tested out the X50 at first on the repeater which could only barely be heard on our Yaesu VX-5, which worked really well. On HF, we were still trying to figure everything out. No matter what we did, we couldn’t get our SWR down. Our dipole was resonant at 1.5:1 for 40 metres, which is what it should be, but infinite through the tuner. Hm. So we ended up listening for a few hours, working out the DSP and other filters. The radio is quite amazing in what it can pick up, compared to the Yaesu FT-707. Early in the day we were able to pick up CE1KR clear as day. South America! Later on a VA2 station from Toronto was on. Only just before the rememberance day contest started at 20:00 local did we finally realise. The bloody tuner was plugged in backwards. I guess thats what happens when you try to operate radio after a few beers.

Once we figured everything out, it worked really well. The contest was a great way to start transmitting on HF. We managed to talk to 30 different Australian and New Zealand stations. We didn’t put a whole lot of effort into the contest, as I had done with previously ARRL V/UHF contests. We ended up going to sleep about 00:30 and listening to the WIA news at 09:00.

Some stations we talked to in Queensland reported we had a strong signal. Quite amazing considering we only have 100Watts and an antenna about 3 metres off the ground. There is much room for improvement, but at least now the upgrades will only be the cost of wire for better antennas

de VK3GNU

Tags: musings, tech by Hannah
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Tried to build a 146MHz J-Pole using wire, following some of the online guides. It seems simple enough: stick a half wavelength vertical on top of a quarter wavelength matching section. The ends of the matching section have very high impedence, while the bottom is very low. So, somewhere on that path is 50 Ohms. I must admit my ability to construct isn’t the best, so the joints and connections are probably shoddy at best. Ended up using a 150 cm jumper coax bought from a local supplier. Cut one end off and connected alligator clips, one to the braid, one to the center conductor. Made few loops of coax about 4 cm in diameter as an RF choke.  Alas, I’ve been told I have a hum in my transmission. Not having an antenna analyser for VHF, I can’t *really* tell where the 50 Ohm feed point should be, but even just a few millimeters off shouldn’t add a hum. I’m a bit baffled. I guess the best explanation is not enough RF choking, and the microphone or IF stage in the radio are picking up a bit of stray RF. Next will be to add a ferrous material to try and increase this.

Eventually, I hope to build a larger J-Pole for 14MHz. This isn’t a very conventional antenna, but will be the easiest for our situation. Having access to a large tree will allow me to put the ~15 meter tall antenna up rather high. It will have a feedpoint close to the shack, at the bottom of the tree. Best of all, it won’t require a huge amount of radials to get a bit of low-take off radiation happening. Hopefully this will work for a bit of DX on 14MHz.

Tags: antennas, musings, tech, vhf+ by Hannah
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Poor little VX-5. I’ve had the thing for years now. It was one of the first radios I got when I became licensed 3 years ago. I had upgraded the stock antenna to a simple, but higher gain, dual band Diamond whip. Unfortunately, the poor thing shattered to bits at the loading coil when the radio got dropped the other day. Back on the stock ducky antenna, I was able to finally hit a local repeater on Mt Dandenong. It seems though the stock antenna just isn’t quite powerful enough to hit them from home. Today though I was able to talk to both VK3PB and VK3TXT on the Olinda repeater. My first contacts in Australia. Yay!

de VK3GNU

Tags: tech, vhf+ by Hannah
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Well playing with Hannah’s HT a Yaesu VX-5 I can pick up the automated voice transmision from the control tower for Essendon Airport. It repeats itself, giving the time in UTC, with windspeed and direction, and temprature. The frequency that this transmits on is 119.8 MHz. Also been able to pick up flights coming into Melbourne Airport. Rather nifty, and kinda boring sometimes. 

In other news Hannah and I popped into Strictly Ham, in Bayswater, to have a look at some radios, I think we’ve decided that we will get the IC-7000.

~Ivy

Tags: musings, tech by Ivy
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Well, got home tonight, and decided to do a quick scan of 80 and 40 meters as I do, got VK3LO nice and clear, discovered why, he seems to be only around the corner which would be why I’m able to pick him up quite well when he is transmitting.

So Hannah and I quickly threw up the wire dipole outside, and discovered that much to our dismay, we got the same results with the wire dipole inside (well it’s a different one, still about 10 meters per pole but up in the picture rail of our room.)

So the (electrical) sounds of the suburbs is still causing an issue.

What we really need to do is try and set up the wire dipole up a bit higher other than just throwing it up randomly in the back yard, and see if that makes any difference.

Or wait till next time we’re at mum and dads again and see what we can do there.

Or look at other antenna designs we can throw together in a cheap and easy manner, and see how they go.

All good fun.

Also saw the antenna tuner for the FT-707 on vk classifieds and by the time I’d got home the thing had sold, got to be a bit quicker.

~Ivy

Tags: musings, tech by Ivy
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Working with the radio at my mother and fathers place is much more successful than at home. The fact that it’s about 60KMs from the city helps. And it’s nice to spend a night in a place without light pollution is really nice.

Anyway Hannah and I set up a basic wire dipole antenna, 10 meters side to side, and strung it up around the decking out the back of my parents place.

This antenna cost us the grand cost of under $5AUD nice and cheap.

Anyway during the daylight hours, we listened in to the 20 and 40 meter bands, even picking up KE6M from california, which was kinda cool.

At night the 40 Meters seemed almost unusable as there was a lot of AM stuff emanating from China, and also a repeating noise that could of been an over the horizon radar system also from China.

But 80 Meters was fairly active, and we filled many pages of my little log book with stuff we found interesting. One of the cool things was a couple of guys talking about how to build decent chokes and baluns from stuff in their junk boxes.

A good day all in all.

I so need to get myself licensed so I can start transmitting.

~Ivy

Tags: musings, tech by Ivy
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Well to be honest I am new to the radio game. I do remember when I was ten or older a friend of my mum and dads was into ham radio. I thought this was amazing, I remember seeing the QSL cards that this person had, including one from East Germany and I really thought this was cool.

But in looking back, I think my interest began much earlier, with a radio receiver that my grandmother had. I can remember little of this set other than it was white, and had many knobs. The two things I do remember receiving on this radio, was the local constabulary talking about a stolen mini, and the Russian woodpecker. I found out what the “woodpecker” was from the show on the BBC many years ago “Tomorrows World”.

Anyway I digress, at home, in the near the City of Melbourne, with a basic wire dipole, I can pick up little other than noise, and faintly the odd voice, of which due to the noise I can’t make head of tails of.

I guess this is what one gets in world where cheap electronics spew out electrical noise. And possibly the trams running on their DC current also could be responsible.

Though to be honest, It could be all my electrical equipment in my room too.

In the end I guess I need a better antenna at home.

~Ivy

Tags: musings, tech by Ivy
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