Sunday, February 12, 2017

An Un-Expected Pleasure on Saturday Morning

Early Saturday morning, first thing I normally do is switch the radio on. It's typical that you build a new antenna and then the band goes quiet on you! In this case it's the 17 meter Moxon, a few European stations can be heard but that's it.

So I decided to take a look round the lower bands to hear what's going on. 80 meters is the usual local traffic with what I jokingly call the amateurs complaining of pains and politics band! Which can be very entertaining, but today I wasn't in the mood. 

Switching up to 40 meters it was mostly European stuff and moving on to 30 I get something similar, but round 10,124 I hear a feint station calling a CQ which takes my interest, cos it's got that echoey sound of distance and no one has picked up on it yet.

A bit of QSB but I can still just hear it calling, I zero in and get the headphones on,  sure enough there it goes again and still nobody has picked it up, wait a sec that's a ZL station ZL3XDJ. In to action I go, filters on, zero the beat, quick ATU check and put the power up and away I go.

M0AUW K pause, back he comes, it's Brian whom I heard a few days back with very nice CW, It does make a difference when you hear good CW! you appreciate the spaces and clarity especially when its DX stuff and especially when you've had a stroke and your brain is just not quite there!

He gave me a 579 and I was so happy, I had a permanent grin on my face all day!

Friday, February 3, 2017

The W5GI Mystery Antenna

One of the first antennas I built was the W5GI mystery antenna, it makes an excellent antenna as a starter project when first entering the hobby.
 
 




The Mystery antenna covers 80 to 6 meters with low feed point impedance and will work with most radios, with or without an antenna tuner. It is approximately 100 feet long, can handle the legal limit, and is easy and inexpensive to build. It’s similar to a G5RV but a much better performer especially on 20 meters.


The W5GI Mystery antenna, erected at various heights and configurations, is currently being used by thousands of amateurs throughout the world. Feedback from users indicates that the antenna has met or exceeded all performance criteria. The “mystery” part of the antenna comes from the fact that it is difficult, if not impossible, to model and explain why the antenna works as well as it does. The antenna is especially well suited to hams who are unable to erect towers and rotating arrays. All that’s needed is two vertical supports (trees work well) about 130 feet apart to permit installation of wire antennas at about 25 feet above ground.


 



Tuesday, January 31, 2017

A Nice Start To The Day

Switching on the FTDX9000MP this morning at around 8am local time, things sounded pretty quiet, so I was  glancing at this months Radcom to see what propagation was about. I must admit things looked pretty grim and I thought I may get a crack at Moscow or a bit further, but it didn't look good.

Using the Hustler antenna I decided to try the 30 meter band and was searching along the band and picked up on a loud Russian station in CW conversation.
I was about to move off to carry on the search when just below the tone of the Russian I could hear a very feint CQ calling.

I didn't get the station name, but he had that echoey sound you sometimes get with distant stations and I felt this needed a further investigation. The Russian finished his chat and then the distant station became a bit clearer, but there was lots of QSB which made things difficult.
This is where the FTDX9000 comes in to its own,I turned the ears up, put in the filters and had a good listen; JF1IRW, yep there it went again definitely calling CQ but at a quicker speed than I'm used to.

Quick as flash I looked at the frequency, move to the dummy load tuned up , noted the time, powered up to 200 watts, held my breath and replied. He picked up on me straight away and came back with a "M0AUW?" I began tapping and that was it, QSO started. I was chuffed to bits, Japan early morning when everything looked bleak. What a great hobby this is, made my day!

Friday, January 27, 2017

A Rotator Question


When I was putting up my 17 meter Moxon the other day, I had to do all the wiring up of the rotator. Obviously the five core cable which is 35 meters long was not cheap; I had to also drill yet another hole in to the outside wall of the shack for this cable to fit through, once connected all up I had to test and then bury the cable so no one was likely to trip over.
This got me thinking surely there was an easier option. Doesn’t anyone sell wireless operated rotators?  You’d think in this day an age that someone would have come up with one. Or am I missing something here?

 
Cable operated rotators?

Tuesday, January 17, 2017

40 meter Delta Loop

Here's a nice little project for a 40 meter Delta Loop I found while browsing the web from a German Amateur called Patrick Henry DJ0IP.

It would make an ideal weekend project.





 

CONSTRUCTION DETAILS:

The pole should be about 12m high (minimum 11m). (39’4" to 36’). Higher is better, but then you will have to re-adjust the total length for resonance.

The feedpoint is located in either diagonal side near one corner of the antenna, enabling vertical polarization. This makes the antenna an excellent DX antenna.

The length of the diagonal is not very critical and may be adjusted to help find a better fit in the space available, but the distance from the feedpoint to the top should be one quarter wavelength.

The exact total length will vary depending on ground conditions at your QTH. Begin with 42.7m (137’ 10") and then shorten the horizontal leg to bring the resonance up to the desired frequency.

Adjust total length by adjusting the length of the horizontal wire. (Easiest way).

The horizontal leg of the antenna on the bottom should be 2 to 3m high (6’6" to 9’10") high enough for humans and animals to walk under. Changes to the height will require adjusting overall length.

The insulator shown directly on the pole at the 2m level is for mechanical reasons. Secure the insulator to the pole, and then pass the horizontal leg through the insulator, reducing sag in the horizontal leg.

The insulator in the horizontal leg near the left is an option for convenience. It enables easy adjustment for resonance by removing or adding wire. For disassembly, disconnect one side from the insulator and then roll the antenna as a single wire. Each time I changed my QTH, I had to re-adjust the length of the jumper. I just let the jumper wire hang down. For permanent use, you may leave this out.

The antenna will have an impedance between 90Ω and 100Ω. A quarter wavelength matching stub of 75 Ohm coax will provide a good match to 50Ω. RG-59 is good enough for about 500w.  If you want to run more power use RG-11

Thursday, January 12, 2017

Repairing the K2

So after diagnosing the problem with the K2 after I had inadvertently wrecked it by transmitting with the FT9000 when the K2 was switched on! I now had to fix the issue.

After a thorough inspection, the problem seemed to be that two PA transistors had blown and so using Don Wilhelm's advice to purchase the K2PAKIT from Elecraft - (that kit has matched PA transistors plus  replacements for Q11 and Q13 both PA2222a), I set to work removing the suspect parts.

Q11 and one of the PA transistors had definitely blown big style and no wonder there was a bang from rig when I tried to transmit. I couldn't see any other issue and I would double check when putting everything back together a by simple series of voltage tests.

Q11 blown to smithereens!
 
 
The blown PA Transistor (the one on the right!)

After a good clean up I carefully read Don's excellent instructions.
"Install Q11 and Q13 first, then check the voltage at the base solder pads for Q7 and Q8.  It must be zero during receive.  Then do a TUNE and measure the PA transistor base solder pad voltage.  If it is not in the  range of 0.60 to 0.64 volts, investigate the resistors in the Q11/Q13  circuit. Only after those checks should you install Q7 and Q8. That should get the base K2 working".

The K2PAKIT finally arrived from Elecraft and I could begin the repair. Removing the old parts proved difficult to say the least, patients and a steady hand is required using the copper flex to remove the old solder. I used an old needle to make sure the holes in the circuit board were back to their correct size, (a little tip I picked a long time ago!) finally without damaging the circuit board I managed to remove all suspect parts. Replacing them was just a case of referring from the manual to make sure everything was correctly placed.

 
You can see where the PA transistors should go right in the centre of the picture, 3 holes in a row,

Unfortunately one of the smaller transistors (Q13) got damaged so I had to replace, which took another few days to order. But finally with much perseverance I got there in the end and after reading up in the manual and following Don's instructions to the letter, everything fitted back together. A quick test with a multi meter all looked good and I switched on, it was working perfectly.
I'm going to keep it as a QRP without the 100 watts, I hardly ever used more than 10 watts anyway so I might as well keep it as the original QRP Rig!

Friday, January 6, 2017

17M Moxon Update

Having built the 17m Meter Moxon and tested the antenna I am very pleased with the results.
Attaching to a 35 foot mast with a rotator however was touching its limits. The mast is in fact one standard 30 foot with a 5ft section added and a smaller section housing the rotator. Normally the mast is held by a large nut and bolt between two smaller lengths of scaffold pole that have been buried two feet in to the ground, therefore providing a clamp to the main pole that can then swivel up and down.

Once in place I can clamp with another nut and bolt that slips in at the bottom, locking the whole thing in place, it worked fine for my 10 meter Moxon but this is a bigger beast.

The problem is that combined weights of the rotator, antenna and cables puts the 35 foot mast at its limit. As I raise it bends quite dramatically and although it does settle when at full height I can't take the risk of keeping it in that position.

So I am going to have to reduce the height of the mast by 5ft i.e. remove the added section, this should strengthen the pole, its just slightly shorter, the attachment is added by a simple scaffold clamp, but the clamp does provide some weakness to the overall mast.

I can live with a 5 foot reduction so long as I know its safe! So at the moment the antenna is lying low with work to reduce the pole on-going. The cable for the rotator arrived the other day and I have already unwound and laid it out, connected to the rotator and it is now awaiting me to insert through one of the walls in to the shack.

 
The antenna and pole resting!
 
With the weekend upon us, I did some final testing I was getting an SWR of 1:2 at 17.185 and a 1:9 at what I wanted at 18.068 right across the band. So it needed a bit of a trim. What I found out later was because I was using pvc covered wire (in fact it was 42 strand speaker cable at around a millimetre width) I inputted the millimetre width within the Moxon calculation, I should have allowed for the PVC cover, so in future this has been noted as I wouldn't mind attempting another Moxon at some stage.
 
 
Further testing with the pole at rest
 
Anyway I trimmed using the 17.185 as a template, When completed I had shortened the director by 150mm and taken 50mm off the  reflector. This brought the SWR to 1:3 at 18.100, so all was well in the end, just a bit of give and take. The height is now 25 Foot and doesn't seem to be a great difference performance wise, only it feels and is a lot safer to put up and stay up!
 
You can definitely hear the difference when rotating, your up against the cobweb, which is not weak but there's certainly a 3/4 db improvement with the Moxon.
 
 
 
The completed antenna
 

It's taken roughly a week to construct, but it's been good fun and if your looking for a quick project I highly recommend having a go with a Moxon.

Sunday, January 1, 2017

How to Blow Up Your K2 in One Easy Lesson!

OK, my own dumb fault, Friday morning playing with the K2 just getting some QRP work done and I had come off the air with German station feeling quite pleased with myself. I decided to  listen to a  different frequency 18Mhz on the FT 9000MP to see if the newly built Moxon would pick any thing up at a height of about 15 feet.

Forgetting completely about the K2 still being on, I hear a Russian station on 18Mhz via the FT 9000 and think blimey the Moxon is working even at that height! I decide to reply, so tune the FT for 40 watts and hit the CW key.

BANG goes the K2! First reaction Jesus I've blown it up! Panicking I quickly carry out some checks, Switch off, this particular rig is fitted with K2/100 (100 watt kit), so I'm really worried I've damaged that particular option. I switch back on, I can still receive OK, all bands OK, transmit tone is still there but no transmit output, what have I blown?

I start to take the K2 apart trying desperately to remember how its all put together, the manuals come out and I start reading thinking did I really build this radio, it's so complicated, I remove the K2/100, get the top cover off then the sides and finally the underneath, back to the bare bones and then start with the magnifying glass and some bright lighting, looking for anything obvious.

Eventually after combing through various circuit boards I find a PA transistor (Q11) on the main circuit board had been completed shattered, this after finding it remains at the very bottom of the radio. Checking all other PA transistor there's nothing obvious. I check elsewhere, I couldn't find any damage with the K2/100, so fingers crossed, this is the only messed up bit.

 
 
 
No wonder there was a loud bang! 

I contacted the Elecraft  forum and was soon in chat with Don Wilhelm who suggested I get the K2PAKIT which has the PA transistors and also replace two diodes as a precaution in case I've blown something else. He instructs me what I need to check and possibly change.

I've put the radio back together and rebuilt as a the standard transceiver without the K2/100 (I only used about 10 watts maximum anyway) and am awaiting the parts from Elecraft, hopefully it's a small bit of damage and that's it, the cost is around 20 odd dollars, but combined international and import postal duties push it up to nearly $60 so it's a lesson well learned.

There will be more info on the repair when the parts arrive, but just imagine if I had decided to transmit the Ft9000 on 2 or 300 watts instead of just 40, god knows what would have happened to the K2!

Delta Loop Comes Down Moxon Goes UP!

Happy New Year to all, I trust festivities were good?

09.20 UK time on new year's day and already I've had my first QSO of the year. Is there something wrong with me? The XYL thinks there is!

Yesterday the Delta Loop was brought down and I have built a small stand at one end of the scaffolding pole which is attached to a tilt over section for ease of use, so at the moment it is lying on its side. The simple stand is designed for easy maintenance work on any antenna that I fit on that pole. This is now ready to take the newly built 18m Moxon and will be mounted as soon as I have the 5 core cable for the rotator.

The mast at an angle and the Moxon waiting to be transferred!
 
 
The temporary mast will disappear for the moment until another antenna project is in the making, In the meantime the paddock will not resemble a building site (as the XYL states) and normality will return till I get another break off work and it all starts again. The grass has yet to make a real appearance on the new paddock, it didn't help with me installing the stock fence, so I suppose in fairness to the XYL it does look rather a mess at the moment, so much mud!
 

I do want to explore the intricacies of the Hexbeam , but I worry about the size even though one of its sales pitches say it is for the smaller garden. Also whether to make or purchase, I could try and make a slightly smaller version without the 20 meters, we'll have to wait and see what 2017 brings.

Thursday, December 29, 2016

17M Moxon Antenna

Over the Christmas break I had another go at building a Moxon antenna. This time not the 10m but a 17m which is a little bit bigger!
I'd had wanted the 20m but I felt it was going to be too big even in the new paddock so I settled on the 17.

Details of the build can be seen on my Moxon page, but below is a taste of the completed build on the twenty foot fibre glass mast, I've just got to mount it on the 35ft aluminium mast with a rotator at some stage. But all the testing is pretty well complete.