A Half Square Antenna for the 40 metre band…

Now that there are social distancing rules that have us mostly at home for the near future, I realised that this is an excellent time to do some upgrades to the VK5LA antenna farm.  I have wanted a low angle, dedicated and resonant radiator for 40M for some time, and recent reading had me thinking about trying a Half Square antenna for that band. The full size dimension would fit easily across my my back yard, and I had available the supports required to get it to the correct height.

An added bonus is that I would be utilising Mmana Gal antenna modeling software and my new nanoVNA to observe and adjust the antenna once erected.

Like many other VK hams, I really enjoy watching VK3YE’s You Tube videos, particularly when he heads to the beach and operates portable…it was this video that started me on the journey for this antenna…if Peter’s antenna worked ok on 20M why not try one one of these on 40M at my place?

For those unfamiliar with a Half Square, the easiest way to describe it, is to think of a single staple, like you would find holding a couple of sheets of paper together.

That hasn’t been used yet!

Now orientate it so the pointy points, point at the ground!

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So as you can see in the above screen shot from the Mmana Gal software, here is a diagram of the  antenna. It is simply 2 1/4 wave verticals on 40M joined by a 1/2 wavelength wire at the top. This diagram show it being fed at the top corner (the small red circle) this is a 50 ohm direct feed point, great electrically, but it’s not very convenient to feed it here as *ideally* you have to get heavy coax to this point and lead it away at 90 degrees for a 1/4 wavelength…not very practical…Other more obscure feed methods are feasible, and you can find them on the internet or in good antenna books if you look hard enough. Perhaps the best way to feed it is at the bottom of one of the vertical wires, far more practical, but tricky electrically!  Nothings easy is it? Using the software, we can see in theory how the antenna will perform when fed with RF at our chosen frequency, at the place we want to feed it…

So let’s run model of the antenna in the software. I’ve told Mmana Gal to feed it in a top corner…

HalfSquare

This image above shows the antenna radiation pattern. The diagram on the left shows the antenna, looking down directly on top of it. You can see that the long halfwave section going from left to right, the feedpoint (red dot) is shown for reference. The diagram on the right shows the results of the modeling and the elevation pattern. We can see here, that at our design frequency of 7.074 Mhz (for FT8), the Gain is 4.31dB over an isotropic radiator, there is a 0dB front to back ratio as it’s radiating equally well in 2 directions, the  impedance at the feedpoint is very close to 50 ohms and that the reactance is very nearly 0 Ohms. I made the lowest point of each the 2 vertical radiators 250 mm from the ground, as I wanted there to be sufficient room without having the feed point in the dirt.

Let look and see what happens if we feed the antenna at the bottom of one of the vertical radiators…this is far more convenient…

Halfsquare2

We can see here that comparing the 2 diagrams, the only real change at our 7.074 Mhz design frequency is the resistance at the feedpoint is now at 3250 Ohms with LOTS of reactance. Other important parameters like elevation angle, gain and vertical radiation remains virtually the same.

So there we have it, here are the plots of the radiation patterns, first, horizontal polarisation and then Vertical polarisation…this indicates that at least some of our vertically polarised radiated power should head towards the horizon at around 23.3 degrees. There seems to be very little Horizontally polarised radiation, and what little there is, is going straight up to warm clouds. Vertically polarised radiation, at a low angle towards the horizon, is what we want.

OK so now we have to put power into the antenna. How can we do this so that the maximum power is transmitted by the antenna?

What we have here is basically an End Fed antenna, in this case on our design frequency of 7.074Mhz, it’s a full wave (1/4,+1/2,+1/4 =1) End Fed. Steve, AA5TB explains all about the End Fed antenna in this link way better than I can…Another way to describe the antenna is an 80 Metre End Fed Half Wave.

So we need to transform the high impedance, in this case 3520 ohms (at the base of one of our 1/4 wave legs) to 50 ohms so our Transmitter is happy to deliver full power.

We could use a matching Transformer, like the popular 1:49 or 1:64 transformers that many hams are using with end fed antenna these days. See here for the lowdown on the transformer construction. A 3 turn Primary and 24 turn secondary version (roughly 1:64) works well with this antenna on the bands that are multiples of a half wave. In this case, 80 – 10M. This is convenient if you just want to push the tuner button on the rig when you change bands, but you sacrifice efficiency and the radiation pattern has many more sharp lobes and deep nulls, with increasing Horizontal radiation at high angles away from the design frequency. That’s not good for DX.

I chose to feed the Half Square as a single band antenna on 40M with a parallel resonant circuit. This is quite efficient and ensures the maximum power is transferred to the radiating element rather than heating a ferrite core in a broadband matching transformer.

John, M0UKD, has an excellent website on how he made a matching unit for his 15M 1/2 wave vertical antenna. I used the information from that site and the calculations to come up with my own matching unit, shown below. I used an old capacitor and coil section I had in my junk box and finished up with this unit. Not as pretty as his, but it certainly does the job…(hot melt glue for the win!)

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Ok, so now we have a design, we have a way of matching it and we have plenty of time on our hands in self isolation to put it up…

I positioned the antenna in the back yard, the height of the two vertical supports are around 11 metres each. It fits nicely in between the two side boundaries of my average size block. Here is one of the vertical radiators,  both supports are lash ups of broken squid pole sections and ally/steel tube sections I had kept/salvaged for projects just like this…never throw anything out!

Here you can clearly see the 90 degree transition to the 1/2 wave phasing wire…

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…to the other Vertical radiator at the other end of the antenna.

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Here is the feed point, here I’ve temporarily strapped the matching unit and a 1:64 Transformer to the stake for testing until I come up with a more permanent setup. The capacitor in the matchbox can be adjusted so that X=0 on an Aerial Analyser or vector network Analyser.

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So how do you adjust something like this? how do you know it’s doing its thing?

Ok, lets go with what we know. We want the antenna to be resonant at 7.074 (in this case for FT8 mode on 40M) so we want a low SWR reading on this frequency and we also want the resistance as close to 50 Ohms as possible with a reactance close to 0 as well, to make our transceiver sing, and develop full power to the antenna.

I was actually quite gobsmacked at what I was seeing on the VNA. This is one of the first readings I took,  I set it to have a centre frequency of 7.075 Mhz with a 1 Mhz span. (this was straight after adjusting the capacitor in the matching box to peak the noise on RX with my FT817 Transceiver). This is what the VNA showed first up. The SWR is 1 to 1.16, the Resistance is 58 ohms with 24.nF of reactance. The frequency is shown as 7.005 Mhz. Moving the marker (the little triangles on the VNA screen) so the reactance is very close to 0, (resonance) showed a frequency of around 7.050 Mhz. So if we’re splitting hairs, the antenna is a fraction too long. The Mmana Gal model prediction seemed pretty spot on. I would only need to make minor adjustments to the lengths of the vertical radiators to shorten the antenna to raise the resonant frequency to 7.074 Mhz

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These numbers makes our Transmitter very happy to deliver full power to the antenna, no tuner (internal or external) needed…

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OK so the $64.000 question, does it work? Well yes, it certainly seems to!

I have the antenna orientated north/south, so it is radiating pretty much east west.

The antenna went up on the 2nd of May 2020 at around 5:00pm local time here in South Australia, here are the first few contacts on the antenna after calling CQ on 7.075 Mhz. 1st up is VK3FAC, who was receiving me at +10dB

Then followed by the USA,  Robert, K9U0 in Portland Oregon with a -13 report…nice, looks promising…

Then the friggen DOMINICAN REPUBLIC answers my CQ call!!! Migue HI3MPC with a -22 report…very nice!

Next? CUBA! Eduardo C07EPP answers at -17…Then I think I had to go have a lie down!! Here is a snippet from my log…LOG

The contact circled in green, with Slovenia is actually on 20M when I was testing the antenna with a 1:49 transformer to see if my radio would tune it on all bands from 80 to 10M with the rigs internal tuner, via the broadband 1:49 transformer…th 30, 17 and 12 Metre bands won’t match which isn’t surprising as they aren’t a multiple of 80, 40, 20 or 10…

So yes, it certainly seems to get out, and in the direction the modelling said it would.

I’ve worked 158 qso’s 19 DXCC entities so far in the 9 days as of 11/5/20 since the antenna has been up. I certainly do ok in the direction of the USA, Canada, the Carribean and Africa. An added bonus is the antenna is very quiet noise wise on RX, and the lack of horizontally polarised high angle qrm signals from Indonesia is noticeable. Also, I don’t get many JA stations returning my CQ calls as well, when before they were in plague proportions…this further reinforced the radiation pattern is favoring east/west.

So there you have it, I have described my journey with the Half Square antenna. I’m very impressed, I’m working stations I could only hope to before! I intend to try a portable version for 20M fairly soon, either near some salt water or a lake, as soon as these bloody social distancing rules are relaxed.

Happy Hamming, Andy, VK5LA

COVID19

 

The globe is certainly experiencing unprecedented difficulties and hardship in modern times. There is little doubt there will be much anguish and uncertainty for a long time to come.

The Riverland Radio Club is very mindful of the strain this is and will place on our radio community. Like many radio clubs many of our members fall into the vulnerable category for a variety of reasons.

To this end our Club has opted to suspend ALL Club face to face contact, including Business Meetings and Tech Nights, to play our small part in flattening the curve. We recognise this action increases the sense of isolation which we feel is in conflict with mental well-being.

So to support our members though this uncertain time we have committed to undertake the following:

  • Business Meetings for Club members to convened over the VK5RLD repeater;
  • Tech Nights replaced with a 80m (3650kHz) Net, all welcome;
  • Members, and all comers, are encouraged to join the WIA News Re-broadcast call backs; and
  • Check into the RRC BRL Nets
    • Sat & Wed, 7115kHz, 0830hrs local
    • Tue, 3610kHz, 2000hrs local).

To all the HAM community, stay safe, stay well, stay vigilant.

Danny VK5DW

2020 BRL Gathering Registrations

POSTPONED   POSTPONED   POSTPONED

RRC regrets to advise the postponement of the RRC BRL Gathering

Saturday, 18th of April, 2020

Ok Folks, come one come all, it’s on again, the BRL Gathering for 2020 is on Saturday, the 6th of April, at the same sensational location, famous for its picturesque setting, Fantastic Hospitality, Great Food and Cold Beer.

DUE TO COVID 19 RISK THE GATHERING HAS BEEN POSTPONED TILL FURTHER NOTICE

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Lunch –  Lunch at the Hotel is a must! Check out the menu and get your taste buds excited for April. The Hotel’s food is renowned for its quality and value!

*Dogs are welcome at the Overland corner Hotel*

 

A 3/8 wave vertical for 20m

 

Building this antenna came about after I wanted to put something up at home specifically targeting 20M FT8 on 14.074 Mhz.

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The 3/8 wave vertical for 20m in my front yard…

I’m fairly time poor so I needed something quick, simple and cheap to get going with asap. Whilst doing a bit of research I came across the winners of the 2018 QST Antenna Design Competition, and interestingly, third place was a 3/8 wave vertical for 20M by Joe Reiart, W1JR. As I’m not an ARRL member, I asked if anyone in my HAM community  would be kind enough to let me have a copy of the article. Several people kindly sent it to me.

Surprisingly, there is virtually nothing on the internet about a practical example about this antenna. I did find an old reference to the antenna, but no solid build details.

In a nutshell, according to the article, the 3/8 wave vertical has the advantage of requiring less radials than your standard 1/4 wave, but is about 50% taller for the same band. A 1/4 wave vertical requires at least 16 1/4 wave radials for good performance due to the low feed point impedance of around 35 ohms, whilst the 3/8 wave requires just 4, having a feed impedance of around 200 ohms. It also sports a lower take off angle of radiation of 23°,  vs 26° for a 1/4 wave (better for DX), and as the radiating current maximum point is 1/8 wave up the vertical instead of at ground level, it is ideal for ground mounting in situations of nearby clutter. It is easy to match to 50 ohms Coax via a simple 4:1 Unun and a series capacitor.

The materials

I decided to go with a squid pole for the vertical radiator, as they are cheap and easy to keep in the air, so I purchased a 6M pole to which I added 2 base sections from older broken squid poles to bring me up to 7.5m in length. This size slides neatly over 38mm PVC pipe, which is the diameter of my portable stand mount that I use for field work. I also had to purchase the 2, FT240-61 Ferrite cores for the Unun and choke, ( I got mine from Minikits in Adelaide) and a box for the Unun (Jaycar) at the feed point. So for less than $100 I was ready to go.

The Unun

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The 4:1 Unun…

This turned out to be very straight forward, and is explained in the article. There is quite a bit online about 4:1 Ununs, I’m sure you’ll have no drama constructing your own. I used Jaycar red and white power cable cat. No. WH3057, I stripped off the black outer PVC sheath and lightly twisted the wires in a drill, then wound on the FT240-61 ferrite core to get the result shown in the above pic…

The In-line choke

The article is fairly vague on this describing it as 10- 12 turns of RG-303 wound “W1JR style” A quick Google returned lots of hits for this, and you can see my resultant choke in the pic…I used RG-316, as it was what I had lying around.

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The W1JR choke…

Mounting it

By now, I had gathered all the materials I needed so it was time to put the antenna together and see if it did what it was supposed to do.

I initially mounted the antenna on one of my ALDI bike stands as that’s what I normally use for testing and portable operating but my initial tests showed there was a LOT of interaction with the stands metal base/legs and support and the antenna. Readings on the antenna analyser were nothing like I was expecting and confirmed when I moved the Unun away from the base, the readings began to move towards something more like I was expecting.

So I then decided to shift the whole shebang to my PVC vertical antenna mount in my front yard…

This is simply a length of PVC pipe driven into the ground and about 600mm protruding out to mount antennas on, with a short extension that the squid pole just slips over…simple! The pictures below show how…

 

I set the whole thing up, with the vertical wire length calculated to 8.010 metres in length and the matching unit lying on the ground with the 4 radials connected. This showed the 50 ohm point to be around 13.8Mhz, so I shortened the antenna to raise the 50 ohm point to 14.075 MHz. I had a variable capacitor in between the unun and vertical, so I adjusted this capacitor to bring the X=12 reading on the analyser to zero. This measured at 7pf, close to the 10pf mentioned in the article…

Gotta be happy with that!

 

 

 

 

 

 

The squid pole ended up being about 7.5 m in length, so the vertical wire and match box at about 7.8m hung just nicely just above the ground on the mount. You can see the match box with its coax capacitor, how the choke ( to keep RF of the coax outer) connects to the match box and where the 4 radials attach…

 

I only had a brief opportunity to have a listen with the FT817 on the antenna, and the receive was very lively, especially on the frequency of interest. SWR was flat, with the radio developing full power on TX.

I’ll update this article when I’ve had a chance to evaluate the antenna on the air…

Andy, VK5LA

 

Reference: The 3/8-Wavelength Vertical – A Hidden Gem. Joe Reisert, W1JR P44 QST April 2019.

 

Long Island Recreation Park VKFF-1724

Long Island Murray Bridge had never been activated until Pual VK5PAS, Ivan VK5HS, and Danny VK5DW joined forces. Check out Paul’s blog here.

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Today (Tuesday 16th April 2019), me, Ivan VK5HS and Danny VK5DW, activated the Long Island Recreation Park VKFF-1724 on the mighty Murray River, at Murray Bridge.  This was the first time that the park had been activated for the World Wide Flora Fauna (WWFF) program.  The park is located about 80 km east of Adelaide.

Screen Shot 2019-04-16 at 4.54.10 pm.png Above:- Map showing the location of the Long Island Recreation Park VKFF-1724.  Map courtesy of Protected Planet.

The Long Island Recreation Park is 8 hectares (20 acres) in size and encompasses the full extent of Long Island in the Murray River, immediately east of the city of Murray Bridge.  According to the Ngarrindjeri aboriginal people, the island represents a lentlin (spear) thrown by Ngurunderi at Ponde (the fish) as it made it’s way to Wellington creating the river.

Screen Shot 2019-04-09 at 1.12.09 pm Above:- Aerial shot of the Long Island Recreation Park, looking south east.  Image courtesy of google maps

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VK5 National & Conservation Parks Award 2019

River SceneWow what a great time members of the Riverland Radio Club Inc. had activating the Murray River National Park for this the 6th year anniversary of the VK5 National & Conservations Parks Award weekend, sitting along side the magnificent Murray.

Op LocThis was to be a club activity for the Saturday, March 23rd. Members interested in park activations, and those newly licenced, were encouraged to come along to have a go and if they wished get a bit of mentoring from those with a bit more experience.

VK5HS Ivan booked campsite ‘Black Box 3’ in the Lyrup section of the Murray River National Park.

Op Loc2

Ivan was the first to arrive at about 0800hrs local and got down to the critical business of getting the billy boiling. VK5FVIN David who is one of the clubs newest members, doing a club Foundation Course recently, was there eager to learn. Shortly after VK5DW Danny, VK5LA Andy and VK5TRM Rob had all come wondering into camp.

OK so with coffee in hand, thanks to Ivan, Danny got into pushing up a linked dipole for 10m through 80m with a plan to start on 40m. With the dipole atop the 7m squid pole and the ends draped out to about 2m it was time to open the HF go kit.

Cool… all go time, but NO! All seems a bit quiet, checking just a bit further and BUGGER. Faulty antenna, open circuit on one leg. Thank goodness we had another, so after a quick swap out we were up and running. A couple check ins to the clubs BRL Net from Ivan and David confirmed we were good to go.

5FVIN & 5PEDanny smashed out CQ Parks for a while and found it a bit of hard going but got enough to register. Good thing it was slow going as he was using VK Port-a-Log for the first time.

David, a new call, wanted to have a look at an Icom IC-718 for which VK5PE Pete obliged by bringing one along. We powered it up and threw the mic at David. He was a bit nervous at first explaining he will just watch for a bit. Pete was having none of that and with just a little encouragement from us David got on HF for the first time as a HAM. The photo above shows Pete (right) mentoring David (left) through making the contacts. David ended up making about a dozen contacts and by the end of that he was sounding more and more confident and fluent. Good work David, well done!

IMG_8401Andy, probably our clubs most prolific parks operator, had set up a station about 30m away using an end fed antenna and his Icom IC-7300. He was operating on 20m for a while, and yes the 2 stations being so close caused a bit of issues but we were all having a lot of fun anyway. Here’s Andy getting cracking signals on 20m, the signal so good the 7300 case was bulging on every syllable. 

IMG_8405VK5FDOG Pongo another new call had arrived by now for a bit of a look see, asking loads of questions and meeting most of the other members face to face for the first time. He’s been a little active calling into the clubs BRL Net a couple times.

Back over on the other side the second linked dipole was still working fine but couldn’t do 80m… so down it come and up goes a third linked dipole that could do 80m (thanks to VK5PE Pete). We got a few solid contacts with VK5PAS Paul, VK5FMAZ Marija, and others.

Lyrup Flats BirdIvan had set up a crossed 2m/70cm yagi for satellite operations so the new calls could have a look at how that works, His set up includes full duplex so he demonstrated how you could tell how well you were getting into the satellite by the quality of your own returning voice. Three passes were accessed during the day with contacts made as far as ZL. Even David had a crack making a few contacts on the birds… I think he was just a little chuffed with himself.

Rob had a bit of Sonde RX gear with him so he demonstrated that as well to round out a bit of variety in he hobby.

By now, with 7 club members there and lunch time approaching, Ivan started to prep for the lunch cook up. Andy had sorted the cutting of the spuds and onions, Ivan cut some tomatoes, and all these goodies with the mandatory snags and chops on bread topped with a homebrew, of a different kind, tomato sauce from Ivan’s personal stock.

IMG_8406By this time VK5TS Rob and partner VK5FSGP Sandy, yet another new call, had also arrived. Sandy had muscled in on the IC-718 (OK it was free at the time) and quickly made a couple contacts. One with VK5FMAZ Marija, announcing that now the ladies had control of the radios.

VK5MRE Ron, fresh from the morning club BRL Net Control duties and other domestic matters, called in on the club 2m repeater for directions. There’s a campsite 3 and a Black Box 3 so he was advised he just needed to come just a little further along the track… and he made it just in time to join us for lunch.

IMG_8412We pulled stumps at about 1530hrs local by which time 10 club members had attended. For our little club this was terrific and what a great time we had. We would like to thank all the contacts we made for being out there and helping to make our day that much more fun.

I hope you enjoyed our story and thanks for reading.

73’s from the Riverland Radio Club Inc.

Assessment Services Restored

Thumbs_Up_Skin-Color.pngGood news! After a short lull in examination services due to a transition to a new provider, the Riverland Radio Club Inc. is back in the position to provide assessments.

We currently have 2 Club Endorsed Assessors registered with the new provider, Australian Maritime Collage (AMC), with another couple or so in the process.

And if you didn’t know, our Club, through our Endorsed Assessors, offers to successful candidates from one of our assessment activities some Club incentives. This includes:

  • Club General Membership for the remainder of the current subscription year. More details HERE.
  • Club General Members also get a discount incentive with Berri Betta Home Living JAYCAR Authorised Stockist.

For a bit more info about our assessment services and licensing stuff have a look HERE. If you want you can also have a look at our Club Endorsed Assessors or the Foundation Course & AMC-AR Assessments page.

…And now for something completely different!

I was lucky enough to be thought of when a dear friend of mine, who runs an antique and curio business, came across this old piece of medical equipment. This set off her NERD meter and she messaged me asking if I was interested!

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I immediately replied yes and she snapped it up for me for next to nothing…the reason being is this thing, the way those knobs are laid out and that big beautiful meter, just screams

ANTENNA TUNER!!!

But before I consider butchering it and using it for a project I decided to find out a bit more about it…

…and basically ran into a brick wall…

There is very little info on the Internet about the device and definitely no manual!

I actually had to read a couple of scientific papers to work out what the unit actually did, and how it works. This was the only source of information on the unit I could find.

So what is it? – It’s basically a medical radiation detector. specifically it detects radiation from medical isotopes that are injected/ingested/inhaled into the body, that accumulate in a specific area, like the restriction/blockage of blood flow, lymphatic system issues or uptake from tumors/cancer. The patient is probed locally at the site of interest with the large silver hand held scintillation detector that detects the radiation, which shows as a deflection on the meter. It dates from the early mid 70’s when, I guess, it was the early-ish days of nuclear medicine…

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So how does it work? It is certainly an interesting device. It is battery powered, by a couple of PP9 9V batteries in series, to give an 18V supply. There is a battery check area on the meter, this is activated by turning the range switch to the “B” position, just up from the “OFF” position. The PP9 battery is still available from a few different places, I’ve ordered a pair to see if this thing still works. It will be interesting to see if the unit is capable of detecting background radiation. I hope it does.

The probes are also very interesting. They employ a Scintillation Crystal and a Photomultiplier Tube to detect radiation from the patient. It’s a 2 stage process. The 1st stage involves the Scintillation Crystal. This is located at the site where the probe contacts the patient, and detects the radio active particles that are emitted from the patient who has been administered a Radio Isotope. This crystal then emits a pulse of light (Scintillation), usually in the visible spectrum. This pulse of light is then detected by the photomultiplier tube and “multiplied”  – resulting in a pulse of current for each radiation particle detected, which is then passed to the instrument itself, where the result is processed and displayed.

The Photomultiplier tube is pushed hard up against the Scintillation Crystal via spring pressure. It is encased in an Aluminium tube, most likely for protection.

There are 2 probes with this unit, one marked “Probe type 235N”, which has a moveable shroud with what looks to be a ferrite or powdered iron inner ring touching the probe surface, with a long, curly connecting lead, and another marked “Probe 235”, which has a moveable, plain aluminium shroud. I haven’t been able to establish the difference between the two probes.

OK, so how does it ACTUALLY work? – much simplified, here is how i think it works…

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The 18V battery supply is boosted by what looks to be a Cockcroft-Walton voltage multiplier, to a high voltage, most likely variable up to around 3Kv. This is all at very low current, judging by the size of the transformer drive circuit, probably in the uA range. The range switch looks like it selects a number of set voltages. The voltage multiplier board is located in the rear of the unit, seen here. The transformer and drive circuitry are hidden behind the panel with the 3 connectors on it.

This high voltage is fed to the photomultiplier tube via the front panel BNC connector and any detected radiation from the probe results in a current pulse that is measured across an anode load resistor by the metering circuit. This pulse looks to then be fed to an integrator circuit, whose role it is to change the pulses received from the probe to a proportional, steady voltage, (i.e. more pulses more voltage) which is then displayed on the meter. I imagine the fast/slow push buttons would relate to the speed of integration. As an example, if the probe detects little or no radiation, (low or no meter deflection) from an area on the patients body and then more radiation (meter deflection increases) when moved to another part of the body, then that increase for that area would be a concern. A practical example of this (now old!) technology was to use this device after injecting the patient with radio isotope Iodine i-133, to detect blood clots in the legs of patients suspected of suffering with deep vein thrombosis. A meter deflection on a particular area of the leg indicated the clot site.

My limited knowledge of nuclear medicine hasn’t helped in deciphering the Isotope control. I’ve learnt that differing Isotopes are used for differing areas on the body, for example, the Isotope Xe133 (Xenon Gas) position is used when checking the lung and brain. How this transpires to readings from a probe that only has 2 connections for +ve and Gnd  is a mystery. More research showed that other Isotopes on the dial are used for checking other areas like kidneys and heart. I’m sure there’s a perfectly clear explanation out there somewhere. Maybe the different voltages are used with the different isotopes…i.e. 1000V range for Chromium51? Who knows? If anyone can add any insight as to how these units operate I would be forever greatful.

The unit is beautifully made. It has a number of quality circuit boards and the wiring is super neat, and has been laced up. it has a number of gold plated edge connectors. It’s all analog, it’s full of IC operational amplifiers operating on a split rail +/- 9V supply. There is a very nice precision 50uA meter movement that would be a bit better quality than your average. The case is a work of art, I have a number of ex scientific instrument cases from England and all are wonderful!!! Should I turn it into an Antenna tuner?

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We have certainly come a long way from using this type of instrument for medical diagnostics. The clarity and resolution of todays 3D medical imaging machines is mind-boggling!!!

On that note I’d like to take this opportunity to wish all BRL blog readers a happy,  healthy and prosperous 2019.

73

Andy, VK5LA

RRC Presidents Message

Well what a year it’s been for our modest little Riverland Radio Club.

This year we have seen our Club members engaged in all sorts of cool stuff, WX Balloon chasing, Project HORUS chases, more activity in the Parks’n’Peeks program, project building, and even back into JOTO. There’s been Satellite activity, we’ve run a successful Foundation Course, assisted in the Riverland Paddling Marathon, and of course the staples of the RRC BRL Gathering, BRL Riverland Nets, WIA re-Broadcasts and so on. For such a modest club I think we punch well above our weight, for which I am proud.

All this good stuff must come with acknowledgements to all those that call into the nets, join our members on air when out and about in the parks, jump into chase cars, run tracking stations, etc. So thanks to all those both members and non-members who have been a part of this year for us.

On the administrative front we’ve almost finalised implementing a new Club Constitution, the website saw a rework, we’ve introduced Berri Betta Home Living – Jaycar as a Club Sponsor (where Regular Members can enjoy a 15% discount), we now have a new structure that includes a number of coordinators, we have ran Foundation course and started new HAMs on their own exciting journey, there is now free Club Membership to new HAMs that undertake a RRC facilitated assessment, just to name a few things.

Our website continues to grow in popularity. We have smashed all previous records, and not by just a little bit! These numbers show some awesome growth… take a look:

  • gold-trophy_1284-1735Views:
    • 6538 – YTD
    • 3180 – 2017
  • Visitors:
    • 1687 – YTD
    • 476 – 2017
  • Likes:
    • 209 – YTD
    • 0 – 2017
  • Comments:
    • 84 – YTD
    • 1 – 2017

Gotta be happy with that growth!

All in all a pretty good year for our Club I reckon, which brings me to a heart felt and special thank-you to our members. I recognise that each member has contributed what they could and I ask for no more that that. Well done all of you.

In closing I would like to take this opportunity to wish everyone the happiest possible holiday season, and hope that 2019 brings everyone a very safe and joyful year.

Cheers and 73 from Riverland Radio Club, and

VK5DW Danny, President

Merry Christmas all