23cm on two Watts and a prayer

A few month back one of the members of my radio club posted to the clubs group.io group that he had participated in the April 23cm UKAC using a his new IC9700 and a tri-band vertical and managed three OSO's.    

His foray into the world of 23cm's had me dusting off my SG-Labs 23cm transverter I had bought a few years previous and had sat on the shelf and actually give it a whirl. 

The transverter is the MKII version and has a power output of 2.5W so real QRP compared to the IC9700's 10W.  The only antenna I had was a similar tri-band (Comet GP-95N) with a gain of 12.8dBi if you believe that?  The feeder was 15m of Ecoflex 10 so feed losses were going to be around 2.47dB.   So all things considered ERP would be around 16.5W.    

Using an FT817 with the above setup I entered my first 23cm UKAC and was amazed to work 7 stations with the best DX being G3MEH at 105km.  

I can't remember now if I used the ON4KST microwave chat during the first contest but I believe I didn't but with all subsequent contests I did.  

Anyway I was actually amazed I did so well with such low power and polarisation mismatch but that one contest had given me the incentive to do the next contest.

For the June contest I made the easiest change I could and bought an 18 element Yagi a  PA1296-18-1.5RB from Antenna Amplifier in Serbia.  The antenna gives a reported gain of 17.16dBi this of course gave me an increase in ERP from 16.5W to 45W which should give me improvement of around half an S-point and of course the 30dB improvement from having no polarisation mismatch. 

You can see from the table below there has been a steady improvement in points and DX though in August there was some great tropo as shown by the fact I worked OZ1FF on 2W though it was mainly sea path but neither the less I was extremely happy.

Month	QSO's	Points	DX Km
May	7	1877	105
June	11	2154	105
July	11	3070	180
August	11	3624	208
September	19	8357	670

So the next easy upgrade will be replacing the current feed cable with Ultraflex 13 but that will only yield another dB but it will be in place for the October contest.   

Next up will be finishing off the 80W amplifier I'm building and sticking it in a box.     The finished unit will have a LPF by John G3XDY, a 80W PA based up John G4BAO well known design with a homebrew controller to switch the pa and tvrx while also displaying output power, temp and VSWR. 

Another change of the 2m antenna system.

Though the 2 x 9 Element Powabeams I put up last year worked well I really wished I'd installed a system that had elevation and so I've now replaced the Powabeams with a small array 4 x 6 Element LFA from Innovantennas.

Justin also provided the H frame as well as a new boom for the 70cm 12 element LFA I had so it could be rear mounted in the centre of the frame.

While I was buying the antennas I also bought a SPID RAS rotator with Rot2Prog controller but more about that in a later post.

The new array took around five days to put but mainly down to the fact I hadn't ever installed this type of system and so it took a lot longer than it would if I was to get it all done again.   The main time consumer is in the fact I don't have a tilt over mast and so everything has to put up with the aid of an Aluminium tower.   

The array tuned up quite well with each beam within a half a dB of RL.

Top Left      Z 50.6, X 3.7, SWR 1.07, RL 28.6

Top Right     Z 52.6, X 3.2, SWR 1.08, RL 28.1

Bottom Left   Z 53.0, X 2.8, SWR 1.08, RL 28.1

Bottom Right  Z 51.9, X 3.6, SWR 1.08, RL 28.2 

The whole array including coupler and 16m of Ultraflex 10 gave an SWR of 1.1:1

Justin kindly send me a theoretical  plot of the array at 8m high with a spacing of 2.2m horizontal and 2m vertical separation.

Theoretical Azimuth Plot.

You can see from the plot the gain is quoted as 17.36dBi with a F/B of 23dB and beamwidth of 24 degrees.  

I took my own plot using the GB3VHF beacon which is near to me and was about to plot the results out by hand when I did a search for a blank azimuth polar plot and instead came across a great piece of software by Bob Freeth G4HFQ called PolarPlot  this small piece of software saved me a good amount of plotting everything myself and I highly recommended it.

I measured the gain as being 18.48dBi with a F/B of 22dB and a beamwidth of 24 degrees so in good agreement with Justins theoretical calculations.

Azimuth plot as actually seen.

The rear lobe are a bit weird but then there isn't much space between the antennas and surrounding builds, hills, slopes, overhead wires but even so it looks very good.

Easy Rotator Control 4 and the Yaesu G450C Rotator.

For ages now I've been reaching across the bench keeping my finger pressed on the rotator controller switch when changing beam heading and I've finally got fed up with the agro of doing this when a PC based solution is available in the form of the Easy Rotator Controller (ERC) from schmidt-alba.

The ERC is small PCB consisting of relays and a ATmega micro controller to monitor the rotator feedback voltage and operate the relays taking on the role of the existing CW and CCW switches.

The controller is available in a number of configurations, I choose to purchase the Version 4 USB controller as most PC's today do not come with a built in serial port.

The controller is available as either a kit or prebuilt.   I  decided to get the kit form, as any respecting amateur would, for £79.47 including postage and packing which is a £20 pound saving on the prebuilt unit.

The kit comes in four packages consisting of a high quality USB cable, software CD, component bag and another bag with the PCB, DC power connector and some cable to wire the ERC up to your existing controller.

Contents of ERC kit package.

The component bag consists of all the components to be soldered onto the supplied PCB.

The supplied kit components.

PCB, DC power plug, cable and PCB standoffs.

The kit has very few parts as you would expect based around a ATMega 328P 8 Bit micro controller, a crystal for the processor clock some capacitors, a couple of diodes and chokes, a few resistors and a small 70cm x 60cm PCB plus the USB interface, relays and terminal blocks.

I started by first installing all the discrete components, IC holders and the USB interface board which took about half an hour to complete.

The completed board minus relays and terminals.

Once the above was completed I installed the rest of the components.

The completed board ready for the IC's to be fitted.

Once the board is completed you apply 12V DC to the unit and test that you get 12V and 5V at the test points located on the DC port side of the board assuming these pan out you insert the ICs and then start modifying the original rotator controller to take the ERC board.

With the easy bit completed the next job is to disassemble the Yaesu controller and do some metalworking.

Taking the Yaesu controller unit apart isn't a five minute job what you need to do is unplug the power cable from the front power switch and then pop out the cable clamp and remove the lead from the case, you next need to desolder the fuse holder from the transformer and remove holder from the chassis again this isn't easy as everything is covered in blue thread lock, next up remove the control cable 6 pin molex socket.    With all the cables removed you now need to remove screws holding the top instrumentation tray to the front and back panels, this is done to allow access to the nuts and bolts holding the mains transformer to the bottom of the chassis which again has blue lock thread, Yaesu really don't want this unit to fall apart. ;-)   With all the above removed you can now get on with marking the holes from the DC PWR and USB ports.

There's a handy sticky label template that comes with the ERC controller which is perfect for marking the hole placements.

The rear of the controller box with the holes cut for the DC power
and USB connector.

Now you can see from the above picture the holes didn't quite align horizontally and this was down to me being a wally and instead of adding a couple of millimetres to the template I did the opposite and removed a couple of millimetres instead, so had I carried out that operation successfully everything would have aligned.   I still ended up with yet another problem shown below.

ERC fitted within the original rotator controller.

If you look at where the PCB stand offs are in relationship to the case fixing holes in the chassis even though there is enough height clearance so that the screws do not foul on the underside of the PCB what I hadn't taken into account was the fact the case wraps around the chassis when screwed together, this meant I needed to mount the PCB using only the two PCB mounts towards the middle of the chassis.   Now this is in fact fine the board isn't being put under any stress though these mistakes are annoying no one will be able to see them.

The original rotator gubbins replaced and the ERC cables attached.

I then replaced the front panel, power supply and original controller board with this done I could strip some insulation off halfway along both the brown and white wires this is so the ERC can be placed in parallel to the rotator and Yaesu controller to measure the feedback voltage which keeps track of the beam heading.

The control button side of the controller. 

Now the tricky part is to connect the blue and black wires from the ERC controller on the original controller heading controls these switches already have a couple of quite thick gauge wires attached to them and attaching the new wires along with the originals is a bit of a pig but if you start with the switch nearest to the mains transformer it's not too bad.

With the ERC controller connected you can refit the outer case and reconnect the unit the rotator and plug the controller back into the mains and station DC power supply you can then move on to calibrating the unit.

On the software CD you'll find two pieces of software one to calibrate the unit and another to control the unit with.  

The calibration is a little bit more involved for the Yaesu G450C rotator in that you need to do an extended calibration.   This involves calibrating at more headings than would be normal.   The general gist of the procedure is to start the calibration software as shown below.

Calibration Software

Once you have set the controllers com port, which you find in the Windows device manager, you'll be able to read the ERC memory.   Next you need to set the rotator fully counter clockwise, using the Yaesu controller, once set to 0 degrees you can perform an extended calibration by using the "Extended 1" function which measures the rotator feedback voltage at 30 degrees intervals once each interval has been measured the software will tell you to advance to the next calibration point.  

A point to be aware of is make sure when you are setting the Yaesu controller that you look straight on to the Yaesu controller heading indicator otherwise you can calibrate to the wrong heading.  

Once the calibration has been completed close the calibration software and start the rotator control software shown below.

The control software supplied with the kit.

Once the rotator control software has started remember to set the com port and wait few moments for the software to connect.   Now click on a point on the compass and the rotator should start to turn to the position you selected and check the Yaesu controller agrees with the software, try this a few times to confirm the calibration if the calibration is off you'll need to repeat the calibration again.

Though the supplied software is ok it's very basic and in fact I replaced with PstRotator from YO3DMU it's an excellent piece of software and though you need to pay 20 Euro's for the licence it's a bargain and I wouldn't use anything else.  The software can set with presets for quick heading changes, you can open a map and click at any point and the beam moves to that head, the other nice feature if you live near the coast is have the beams turn into the wind when the wind speed exceeds a threshold of you choice.

PstRotator

This is one of those projects that starts off as a 'nice to have' which turns into 'how did I ever manage without it' I'm sure no one would regret adding the ERC to their rotator controller.

2m Antenna Update

After spending next to four weeks off the air due to the new antenna system suddenly going high VSWR 6:1 the guys, Dave and Fred, finally managed to get the system down for us to check where the fault lay typically when I test the VSWR before taking it down the fault had cleared on its own.

Originally the system gave a VSWR of 1.1:1 until it rained when it went high, now since that point it hasn't rained so I can only assume during the intervening period whatever had got damp had since dried out.

All the connectors looked dry with no indication of water ingress seen, the coupler was also bone dry.   The powabeams use an ABS moulding to fix the driven elements to the beam and this is glued shut during manufacture so it's impossible to open without destroying the moulding in the process.

We put more rubber sealant on around the Powabeam ABS moulding, the end caps on the coupler and around the N-Type sockets on the coupler as well I also wrapped self amalgamating tape around the ends and over the centre hole that gives access to the middle socket.

We then put the system back together with all joint resealed with amalgamating tape it now looks like it should take being dipped into the sea before it leaks but only time will tell.

The only modification we made was to make the quarter wave chokes as depicted on the Powabeam website originally we put the loop over the back of the beam which certainly worked however both Dave and I have Powabeams and switched the recommended way of creating the choke which we both agree seems to give a better response.

I used the system again in this weeks 2m UKAC and it worked flawlessly so fingers crossed it'll carry on working.

Again a big thanks to Dave M1DNJ and Fred for doing all the manual labour.

New 2m Antenna Is Finally Installed.

With the help of my nephew Fred and Dave M1DNJ I've finally got the two new Powabeam 9 ele CQM's installed, see my previous post for specifications.

Fred got the job of taking down the original system which consisted of a single 9 ele LFA from InnoAntenna this antenna has worked faultlessly and in fact I only switched to the CQM design due to weight, I don't have a tilt over mast so the stub needs to be lifted into place with the top beam as well as the coupler and 70cm beam by hand not a easy task while standing on a ladder, the LFA even survived being dropped into a hedge from 8m with the rotator and mast attached when the guys from MM0CUG took the antenna down before fitting it to the new mast.

The original 2m LFA with a 70cm 12 ele above.

The first thing to do was remove the original antennas Fred duly got on the steps and disconnected the antenna tails and loosened the rotator stub clamps.

Fred disconnecting feeder and loosening clamps

With antenna removed Fred G-Clamped the new rotator cage to the garden bench and fitted the rotator and thrust bearing which we both proceeded to align. 

Rotator, Thrust Bearing Fitted and Aligned. 

With the rotator and bearing completed Fred got on with the task of fitting all 18 parasitic elements as well as the driven elements to the booms ready for installation.

Fred with set square fitting the parasitics.

Dave M1DNJ and Fred along with Amber then got on with fitting the rotator cage including stub mast, top beam, power coupler and 70cm to the mast thank the gods Fred has good arm strength and a taste of heights.

Stub with top beam, 70cm beam and cage fitted.

Next up was fitting the bottom beam to the mast. 

Bottom beam being attached to stub.

And finally connecting up the bottom beam to the coupler and jobs a good un. 

Coupler connections all done.

And lastly fixing the cables to the mast.

All most done.

Hurrah the finished system finally raised.

The new system raised.

The system gives an VSWR of 1.1:1 @ 144.300MHz with a resistance of 45ohms and reactance of 2 ohms.  

I must give thanks to Dave M1DNJ, Fred and Amber putting up with me trying to run them over with the wheelchair while I fretted over various bits and pieces.   I've been told I'm quite OCD about my antennas. ;-))

UPDATE : 6th September 2018 --   Well the first hard rain since putting the antenna up and the SWR has shot up to 6:1 oh bother this means sadly I'll be off 2m for awhile until I can get the antennas down and workout where the water has got, I suspect the Powabeam driven element ABS moulded fixing block which I had heard can give issues I thought I had sealed it up with extra sealant but obviously not!

2m Antenna Upgrade.

I current have a single 9 Ele LFA from G0KSC and though I have no complaints regarding the antenna I'm now at a stage where the only place I can make a sensible improvement in my 2m setup is to replace the antenna.  

I would have liked, probably like most amateurs, to have more the space to put in an array of four 9 element antennas however this isn't practical on my property.  

Now I would like to give EME ago at some point but I don't have elevation available so this put me in a quandary how to improve the system why still allowing myself a little bit of freedom to still carry out a few EME and Meteor Scatter communications when conditions allowed but also give me a better score in the RSGB 2m UKAC as well as general tropo, E's etc QSO's.

I had a chat with few local amateurs I discovered one of them M1DNJ has a similar setup to myself but has a better antenna and mast setup after numerous discussions with David I decided I go with a 9 Element G4CQM design made by Powabeam antennas a CQM9C4 as the performance looked to be about the same as the LFA but with the bonus it's lighter in weight so would make lifting on the mast much easier to accomplish as I don't have a tilt over.   I decided to go with a of two stacked Yagi's.

Richard at Powabeam has published the specifications for a single Yagi as well as a quad array but I couldn't find the specifications for a stack of two so decided to run the simulations myself.  I'm not going to go through all the figures and configuration that can be deduced from the Powabeam website and the images below.

4nec2 - 3D - 2 x CQM9C4

Total Field - 2 Stacked CQM9C4

Horizontal Plane - 2 Stacked CQM9C4

Verical Plane - 2 Stacked CQM9C4

TANT - CQM9C4 - 2 x Stacked Array.

2m quarter wave coupler

I'm just about to update the 2m antenna system moving from a single 9 element LFA by G0KSC to two 9 element CQM9C4 Powabeams stacked.   To stack the two yagi's you need a coupler to join to the them together.

A quick search on the net I came across two ways of doing this one based on using coax and the other using aluminium box section with a 15mm copper pipe forming a square piece of coax.

You can buy a ready made coupler but I so happened to have a piece of aluminium box section of the correct length as well as a piece of 15mm copper pipe and three N-Type laying around so I though I'd see if I could save myself £70 and build one myself.  

The way to work the dimensions you use a piece of software called appcad this will allow you to calculate the length of the inner copper pipe which turns out to be 520mm for my size of aluminium box I followed the design for the two port coupler from DG7YBN's website.

What I found was the length isn't particularly critical but the distance between the copper tube running thought the box section is my ali box has an inner dimension of 24mm and as mentioned before the copper pipe is 15mm which requires a spacing of 4.5mm to obtain this I wound insulation tape around a screwdriver until it conformed to the 4.5mm and then used this to centralise the tube in the section.  

An afternoon with the hacksaw and drill press I had the basic coupler built and I ten minutes with a 100W soldering iron had the copper tube soldered to the N-Type sockets.

I tested the coupler on the VNA and got a return loss of around 25dB and a VSWR of 1.1:1 which is near enough so I'm a happy bunny.

I'm still awaiting the materials to build the powabeam yagi's but I'll post again with the build and how they went together.

2m Quarter Wave Coupler Results @ 144.3MHz

Vine 6M4DX

A few weeks ago a message came up on my radio club message board offering a Vine 6M4DX 4 element 6m beam for sale, now I've not worked much on 6m and in truth I don't tend to working on anything other than 2m and 70cm but the antenna was cheap £40 pounds so I emailed the seller Colin and bought the beam.  

Now I wasn't holding out for much as it's a secondhand beam but upon picking the beam up I was pleasantly surprised as the beam came in the original box and been taken down and packed away with the bits marked and fitting placed into plastic bags, happy days.

I thought that the beam was missing any instructions and I was unsure of how to fit the hairpin match so emailed the manufacturer which I discovered had ceased trading in 2016 but there website is still present with an email so I emailed them not expecting a response.    To my utter surprise Ron at the aforementioned company emailed me back with 12 hours with all the specs and fitting instructions  which I thought was amazing and I only wish some companies that are trading could match this defunct companies customer support. 

The Vine 6M4DX has the following radiation pattern. 

6M4DX Radiation Pattern

I also managed to pick up for free an older rotator and controller so this would get me QRV 6m for next to nothing from a friend of mine so even more happy days.

Here's my nephew Fred and my mate Mal G1NOX
baking in the sun putting the beam together. 

It took Fred and Mal about 4 hours to construct the beam and get it up on the chimney.

The completed beam up on the chimney stack

When I tested the VSWR the beam gave less than 1.5:1 across the whole 6m band which is fine for my purposes.  

Now typically once the beam was up the rotator controller died within 5 minutes, oh bother so I need to fix that before I can the beam a full work out.  But all in all a great bit of kit for peanuts and gets me active on 6m.

M0CVO HFC-3015V Vertical Short Antenna for 40m - 10m

Recently I had a new mast fitted for my 2m and 70cm antenna's and in the process lost the centre support for my HF doublet and needed something to replace it that wasn't too intrusive.  

I was toying with another centre feed antenna of some kind however I have a particularly small garden with no trees or other readily available supports for antenna's and no easy to access to the ground due to the garden being covered in decking I decided a vertical that didn't need a ground spike was probably the way to go.   Being disabled I also wanted something I didn't have to make myself, sadly I'm past that point in life.

I found the HFC-3015V via Google it's a 1.7m tall, designed for flat dwellers and people with small gardens and according to the website will tune with the internal ATU fitted in most modern rigs on the 30 15, 12 and 10m bands as well as 40, 20 and 17m with an external ATU and some counterpoises and handles up to 300W, I never use more than a 100W on HF so more than adequate.

HFC_3015V

The antenna is made from 40mm PVC-U, polypropylene, waste pipe by the looks of it and has a wall thickness of 2.5mm.  

A fairly thick piece of wire spirals up the pipe from the balun, could be an unun,  to about half way along and then wound into a coil of approximately 30 turns and then again spiralled to the last loading coil which is about 90 turns.

Now you're meant to fix this to a mast using standard mast clamps as depicted below.

Style of clamp supplied with the Antenna.

However I'll use two slightly different clamps which I feel will hold the antenna far more securely, depicted below.

New style clamp.

I'm also going to slide a piece of wood dowel inside the pipe so that the clamps can be tightened without fear of deforming the PVC.

I plan to fix the antenna to the chimney stack using a standard lashing kit, which is already present, on a section of 48mm scaffold pole which is again already fitted.

The website says the antenna is IP56 rated and may only need some self amalgamating tape on the SO-239 feed point.   You can see in the picture below the balun, though it looks to be well made I still think I'll put some more sealant around the box seal as well as rubber coat the antenna and counterpoise connections as living by the sea tends to destroy all type of metal fixing very quickly.  I would have liked having a look inside however the screws felt extremely tight remove.

HFC_3015V Balun

I'll use an LDG RT-100 remote ATU with the unit and fix that to the same supporting mast as the antenna.    I'll also fix three or four 1.5m counterpoises to aid with matching on 40, 20 and 17m.

I'm still not convinced that the antenna will work that well, the M0CVO website doesn't hold any more details other than what bands it'll work on,  but we'll have to wait and see but for 70 GBP I thought it was worth a punt.  

I did think about modelling the antenna in mmana-gal but shock a little at the prospect of adding all the wires for the spirals and loading coils.

Anyway as is always the way with these things as soon as the antenna arrived the MetOffice forecast rain for two weeks, typical!  Once erected and on air I'll let you know how I get on and whether or not I thought it was worth the asking price.  

New Antenna Mast from MM0CUG

My original antenna mast consisted of a 21 foot scaffold pole attached the side of the bungalow via T&K brackets however over winter I noticed that this was causing some damage to the brickwork and so I decided to replace it with a free standing mast from MM0CUG in Aberdeen.

The new mast is 8.5 metres tall however 1 metre is buried in a large block of concrete so 7.5 metres in total and is approximately 1 metre taller than the original scaffold pole.   It's a telescope design raised and lowered by a heavy duty winch triggered by a remote control, so no going outside in bad weather to raise and lower it.

The winch is powered by a battery which is a kept topped up using a 2.5W solar panel.

The guys from MM0CUG kindly took down the scaffold pole for me and moved my antenna to the new mast all within a day.   I still need to do a little tidying up regards cable routing etc ... but overall a stress free project.

Below is a few pictures taken on the day again from the luxury of my living room.

The initial hole cut in the decking

Digging a hole

Mast stub concreted and mast inserted

Getting ready to attach the rotator and antenna's

The new mast in the lowered position.

The mast extended.