Wednesday, April 30, 2014

Catapult Antenna Launcher

My latest toy to hang antennas up in the tree is a catapult with an old fishing rod, a fishing reel and heavy lead weight attached. The rod splits in two so I have just used the base with the catapult attached via two jubilee clips. 

The idea is to fire the catapult over the targeted tree branch thus releasing the fishing line. Once happy with the positioning of the line over a branch, you attach a stronger piece of cord to the weighted end of the fishing line and reel in back over the tree branch. Tie the two cord ends together so that you have a long loop then you can add the antenna to the loop and pull up and down to your hearts content. 

I've seen the idea on a couple of web sites and thought I'd give it a go as I wanted to raise the Windom up in my silver birch tree to the maximum height possible, thereby raising it a further 15 odd feet to about 35 feet in total, hopefully this will improve the transmit/receive. 

I've done some testing with the catapult in a local field and it seems to work reasonably well getting a distance of roughly 100 feet without really trying. I'll put it to the real test (excuse the pun) over the weekend and we'll see what happens.

Tuesday, April 22, 2014

Rebuilding a Carolina Windom 80 from Radio Works

A long time ago I bought a Radio Works Carolina Windom 80 Special from an amateur who had been using it for experimentation. I think he was using it for a write up he was doing for some radio magazine, I forget which but either way he was selling it on Ebay and I got a bit of a bargain. 

The trouble was the antenna was so long (133 feet total, 50ft and 83ft with a 22ft vertical radial) I had it wrapped round the house and all over the garden, so I never really did get it working properly. 

In the end I put it away in my shed and forgot about until I came up with the idea of making it a CW 40 by reducing the wire to 66 feet total (25’ and 41’) with the vertical radial shortened to 10ft. I figured rightly or wrongly that the “matching transformer/balun” and “Line Isolator/choke” were exactly the same for the 80 as was the 40. There was nothing to contradict that on the Radio Works website so I went ahead and reduced. 

The antenna worked reasonably well and I got some good contacts, but I never really felt that I'd got the best out of it and with various wires hanging all over the garden (I had other antennas up at the time) the XYL was none too pleased. So under orders I removed the Windom and a few other antennas and instead constructed my first cobweb as a single replacement.

The Windom got put away and I used the wire for other antenna projects, the balun and choke which remained attached got stored away in my shed. 

With the recent work on the G5RV and whether I add a 1:1 balun reminded me that I had these items somewhere in the shed, so I dug them out to take a fresh look and see if a) I could use the 1:1 balun/choke for the G5RV, or b) perhaps have another go at the “Windom” project. In the end I chose the latter since it would be a shame to waste the balun and choke while they were still attached and also I had just ordered guanella 1:1 balun kit for the G5RV.

After taking a good look there is no problem with the 4:1 balun and I can certainly remove the old remaining wire and re-solder some new, so I think it’s just a case of getting the correct wire measurements and seeing how I get on. 

My only concern is that the balun is the same for a 40 windom as it would be for the 80, (had Radio Works altered it in anyway?) But in all honesty I cannot see what would change, it should still be a 4:1 balun? 

Re-checking the website I still cannot find anything to doubt my theory,(if anything I just think it's a better constructed balun), so I'm going to go ahead and re-attach the wiring and see how it performs. 

The other major factor which will now help me is that I have my own MFJ 259b before I had to borrow my brother in laws with limited time to use it and I had little knowledge in using it. So now hopefully things should be a little easier and clearer with plenty of time to get things right.

As a further update as I have now virtually completed the rebuild. Both lengths of wires have been re-soldered to the balun, theses have been cut to an approximate length of 46' and 25', the balun to choke coax remains at 10'.

All neat and tidy ready to be tested and trimmed.

This then give me room to manoeuvre as once again too much reading on the web starts to do serious brain damage. I've seen and read there are various possibilities as to the correct lengths
From 14% from the centre, to 43'-23' or 46'-20' and the list goes on! Its all to do with finding that sweet resonant spot and I guess different lengths will favour different surrounds, I just have to find the correct one for my location. 
It should prove rather interesting!  

Well today it’s pouring with rain but being somewhat keen in getting the Windom back up in the air to do some testing I've braved the weather and hung the antenna up. It’s hanging at about 30ft in the inverted V position with the wire trimmed to 41.3’ and 25.1’ respectively; this is the best trim I could get at the time with the antenna analyser, but when its pouring with rain it’s not the most ideal conditions to try and get the best out of the antenna. 

It’s by no means perfect and I will continue with the trimming with the MFJ 259 once the weather clears up a bit, but so far I can use the auto tuner on the FT1000 MP V for all the bands so I must be doing something right!

Monday, April 21, 2014

Half Size G5RV

The first antenna I ever bought after gaining my licence was a G5RV. I think it cost me around £30 and it used to hang in my garden, squeezed in some tiny area at the back of my house! But I couldn't complain I got a signal out and had contacts all over Europe and the east coast of the States. It suddenly dawned on me last week that I had never actually built one and it was about time I put that right. 

If you trawl the websites you’ll find plenty of examples and I decided upon a half size build, this purely because I had my old Mystery antenna sitting in the shed doing nothing and I could cannibalise that and use the wire for the half size G5RV. 

The W5GI Mystery antenna is similar to a G5RV but W5GI (now SK) used coax stubs to give what he called “a coaxial colinear array on 20m”. It consists of a half wave length (at 20m) of 300 Ohm ribbon that feeds a dipole centre. I made one many moons ago as an experiment (see previous posts) and it worked very well. 

The measurements for a half size are listed below and with having the mystery antenna already made up it was a quick case of re measuring and then trimming wire where necessary. I noticed some measurement do vary especially the matching section, (look at the picture (above) which states 17' and the table (below) that lists 15.6'), which is correct - take your pick?

So by the end of an afternoon I had the antenna made up and ready for hanging in my silver birch at approximately 25ft. As a change I decided on an inverted vee and after a quick double check of all connections and making sure the angles were good I connected up via manual ATU to the FT 1000 MP. 

Band Coverage
3.5 - 28 MHz
1.8 - 28 MHz
7 - 28 MHz
Length of Antenna
102 ft ( 31.1 m )
204 ft ( 62.2 m )
51 ft ( 15.55 m )
Matching section :

- Open wire
33.7 ft ( 10.28 m )
67.5 ft ( 20.56 m )
16.9 ft ( 5.14 m )
- Ladder line
31.3 ft ( 9.54 m )
62.6 ft ( 19.08 m )
15.6 ft ( 4.77 m )
- "TV" twin lead
28.5 ft ( 8.69 m )
57 ft ( 17.38 m )
14.3 ft ( 4.35 m )

Normally I would put any home brew antenna through the MFJ 259 for checking, but the SWR readings on the G5RV would not be 1:1 and would certainly have me scratching my head trying to get all the bands to an acceptable level. In the case of a G5RV you use the tuner to do most of the work.

So initial results are I have to admit, surprisingly good! 
I manage a couple of QSO’s on 20 meters and on 30. Interestingly 40 meters proved more difficult to tune up, but eventually I got there with some gentle adjusting. I also tried all the bands with the auto tuner on the FT, all was OK except 40. I then brought out the MFJ 259 and SWR on 40m was way up compared to other bands. 

Checking on the web I looked for any mistakes I may have made but the only conclusion I could come to was it maybe an issue with the height as 25ft is not that high and at 40 meters virtually the whole of the antenna is used to radiate. 

Also as a precaution I added a choke balun at the base of the 300 ohm part of the antenna. Of course this where the 300 ohm feeder is attached to the 50 ohm coax (or to be absolutely correct the 75 ohm). You'd think you'd have a 4:1 balun, but then I've never really been an antenna theorist, I just build them!

Further reading from the web I came across the W2DU balun which looked to suit my purpose nicely. It states, "The W2DU bead balun consists of 50 FB-73-2401 ferrite beads over a length of 1ft coax. 


Sadly not having the correct beads I added what spare ferrite rings I had to the coax, which for the moment hopefully may have done the trick but I will find some proper ferrite beads at a later date. Unfortunately the W2DU balun looks to be only available in the US and although fairly cheap the shipping costs to the UK are not! So I will either have to replicate with a home brew or find some other 1:1 Balun. 

A mish mash of ferrite rings but it seems to work!

Now manually adjusting the tuner for 40 meters is a little easier but in theory it should be the easiest band to tune up, so I think something is still not right, (probably the balun) but for the moment I'm just happy to get out and  have fun with my new antenna!

As a Further update I have been reading up on baluns for G5RV's and what a can of worms you can open with the statement " to have or to have not"! 

It looks like my home made necklace of ferrite cores will not do the trick, so today After reading G3TXQ's interesting article on the G5RV I have taken his advice and bought a simple 1:1 Guanella balun. 

The Guanella balun fits nicely in to an old plastic screw container, it's now a matter of just connecting up to the G5RV and see if the performance will improve.

Steve Hunt, G3TXQ is a bit of a guru to me, he has a wonderful website all about Amateur radio with a lot of very useful information on antennas and antenna theory, well worth a look especially if you are in to HexBeams or Cobweb antennas.

Thursday, April 10, 2014

LDG Z100 Plus Autotuner

I've been getting a little tired of manually tuning up the K2 with my Tokyo HC-400L tuner. I know it’s me being lazy and I should know better, but hey when there’s an auto tuner out there that will do the job for you well, what the heck! 

Having my three transceivers connected up at one time means that my set up is a little different. I have three antennas, the cobweb, my 30 meter vertical and my W3DZZ trap for 40 and 80, so I have all three connected up to my Tokyo ATU and then to a homebuilt connector box which switches over to each individual transceiver I want to use. 

When operating with the Yaesu FT1000MP MkV I can bypass through the Tokyo and use the auto ATU from the FT or when using the K2 or OHR100A I can use the manual override and manually adjust the ATU for each radio. Complicated? No once you get used to the idea it works fine! 

The LDG Z100 will be set it up through the K2, so it will be K2/LDG/ with the bypass set on the Tokyo, and then through to the connector box on out to the antenna. To be honest I wasn't sure it would work, but it does and I'm getting out OK. I’ve only tried QRP as I don’t want to tempt fate just yet but the ATU is tuning up nicely against the K2 and so far so good. 

In the UK the LDG Z100 retails for around £140 which is a fair sum, but I've been meaning to purchase one for some time and I thought I’d probably have to go down the 2nd hand route. Luckily I found a site on Ebay, a Greek radio dealer who was selling the ATU for under £120, a fair bit cheaper than the UK, so I bought one. 

It arrived well packaged and only 5 days from ordering, so first impressions on opening the packet are pretty good. Nice clear instructions are provided and it’s dead easy to connect up with the usual TX and RX coax inputs, a ground and a power connection for 7–18 VDC 100ma. I’ve connected power via my PSU for the K2 and it works fine. 

Initial tuning is pretty easy, you have to select the required band, transmit a carrier and hold the tune button whilst the ATU does its business, all very quick and efficient. I've done a couple of QSO's and all is behaving as it should so touch wood I'm very pleased with this little ATU. Now I’m looking forward to having a real play and thankfully no more trying to remember the settings for each band and adjusting the manual controls on the old Tokyo.

Wednesday, April 9, 2014

MFJ 259b Antenna Analyzer - An Update

Going over some previous post I see that a lot of people have read my little summary of the MFJ 259b. This is what I originally said: 

"The MJF 259b has finally arrived, it’s a fiddle though, you would have thought you’d get the power supply with it, but no, that has to be ordered separately, typical! So now I'm busily checking around the local hardware stores for an AC DC adapter with the right connector, it never comes easy does it? 

On surfing the web I came across a UK Amateur dealer who wanted £68 for the MFJ 99x accessory pack which includes the dip meter coil, carrying case and you guessed it the power adapter! Having checked out the web I can get a power adapter for £6.50, makes you wonder doesn't it? 

The other pain is that I knew it took rechargeable batteries, but I was rather taken back when I realised it needed 10! Removing the front cover to install the batteries requires the removal of 8 screws; you'd think MFJ would have come up with a simpler design? 

However I digress, last night I popped round to my next door neighbour and asked if by any chance he had a 12v power adapter, he did and blow me it fitted! So I was able to do a quick test to make sure all was working as it should, interestingly enough all my antennas were slightly out on the SWR readings, most likely from the recent storms, but over the weekend as a simple experiment I will borrow my Brother in Laws MFJ that I originally used to set them up to see how good the SWR matches are on both units, that could prove very interesting!!" 

I never did complete the last bit until much later, well it turned out that my MFJ wasn't too far off my brother in laws, I must admit I was expecting it to be way out.

Now that I've owned this piece of kit for some time and am a regular user I am probably now able to give a better report. The analyzer is actually a very useful especially if you are in to or going to make any sort of HF VHF antenna system. It's fairly easy to use with simple instructions, but if you get stuck just "google" and there are plenty of users out there who will help you.

However, in my humble my opinion it's not that well made, it's rather tinny, it doesn't feel very solid and to be frank feels rather cheap, but of course we owners know it don't come cheap; £300 plus I believe is the present asking price for a new one, so spare your blushes go 2nd hand if you can, believe me they are fairly easy to fix!

Mine does have some drawbacks, somewhere within the area of the coax connector there is an intermittent short, so whenever I connect up my coax cable to the connector I have to fiddle about to make sure I have a good connection otherwise I get a reading or +25 on the SWR. 

I've tried to find this short but it still is escaping me at the moment and it very annoying. More to the point it’s been there since new which doesn't exactly give me any comfort with MFJ products especially since they all seem very expensive! 

As a footnote I eventually found the issue and this is precisely the sort of thing I'm talking about when I say "cheap". The problem was a simple soldering connection of the inner (live) coax connector. The soldering looks and is quite frankly rubbish and once I'd done the fix correctly all was working how it should.

Something had obviously gone wrong when this analyzer was made up at the factory, look at the actual connection, the soldering is that bad the connection has failed.

I have extra bits I've made for the analyzer, I'm not going to purchase any bits of kit if a) I can make them and b) they are always far too expensive!

The loop coupler I use for measuring my homebrew traps; It’s dead easy to build and I strongly suggest you build rather than buy otherwise you may find yourself spending a large amount of money for what can be made in a jiffy at very little expense. 

If you have a good soldering gun you just take was some reasonably thick copper wire (about 6” in length) bend in a circle but keep ½” of each end straight. Take a male to male 259 connector and it’s a simple case of soldering one end of the wire to the centre pin and the other to the outside ring. So you finish up with a circle of Copper wire attached to the male to male 259.

The other piece of kit I made was a frequency counter lead out of some coax and with a PL259 connector at one end and the probe on the other. I used this for working out the frequency measurements on my K2, very useful and very cheap!

Overall, an essential piece of kit for the shack. 
Sometimes you'll get lucky and have one that has no issues and when they work correctly they are very good, but there are other analyzers out there at a cheaper price that do the exactly the same thing. 
In other words, "you pays yer money and takes yer choice!...Hope this helps.

Revisiting the 60 Meter Band

Having been somewhat dismayed when I first listened in on 60 meters I thought I’d better give it another go and see if the awful abuse I heard before was just a one off incident. 

So I put the old inverted vee back up and had another listen to see what was about. There were a few amateurs on sideband and some interesting conversations, but quite honestly I am still surprised how quiet the band is, I didn't hear any CW at all. 

For the past week I've listened most mornings, afternoon and evenings but I can probably count the number of amateurs I've heard on one hand. Admittedly the band is used on a secondary basis but it is very quiet. 

Then finally on Monday afternoon whilst sweeping across the band I crossed over 5.325 heard some voices, so I fine-tuned and there they were, back again, swearing and cursing with the most obscene language and believe me I'm no prude! 
I appreciate that not all users of 60m are licensed amateurs and 5.325 is not in one of the UK 60m frequency blocks but listening to that language does put me off. By the sound of their accents they were from the South West, possibly Gloucestershire or Bristolian and they seemed to be talking a lot about fish, so one can only guess these are local fishermen. 

It’s a shame really because 60 meters can be a great band, I remember back during my military days being stationed for a while in Belize and having to set up a radio station to contact our main base which was at Bruggen in Germany. 

I worked with a Royal Signals chap who was very knowledgeable and together we set up a nice little radio station by the main runway of Belize airport with a massive dipole system and over a period of weeks we had some great contacts with other military establishments all over the States. 

We actually had some success with Europe contacting the base at Bruggen on a number of occasions and I specifically remember using 5 MHz for a few attempts and managing some reasonable contacts!

Tuesday, April 8, 2014

Playing with a HyGain 18-VS

The other month we had our local radio club junk sale, everyone brings in something to sell and we have a good natter and lots of items get exchanged. It’s normally a very good event and gives all the members a chance to catch up and see what we are all up to. 

I brought in a tired looking 2m collinear and my home brew 2m yagi to be redistributed, both items had been sitting in the shack doing nothing and I needed the room for other projects plus they could be put to good use by another amateur instead of sitting there doing nothing. 

Whilst rummaging around looking at what other people had brought in to sell I noticed a chap with an old Hy Gain 18-VS vertical multi-band antenna. I vaguely remember my brother-in- law having one but always being a little frustrated because on each band change you had to go out to the antenna and manually alter the connection to the coil. To add to his frustration he always forgot the exact position he should set the connection and always ended up digging out the antenna analyser and resetting the SWR! 

This particular antenna in the sale looked like it was all there, but it certainly needed a good clean, the owner only wanted £10 and considering that a new one was over a £100 I thought I’d buy it and have a play to see if I could do something with it. 

After giving it a good clean and checking the manual I immediately realised that the antenna had been altered. Instead of the usual tatty coax connection above the coil, a previous owner had put in an SO 239 socket at the bottom of the antenna to make things a bit tidier, however, with that connection in place the coil was being bypassed therefore was useless. 

Investigating further I realised that the antenna had been set up as purely a mono bander, the previous owner had obviously given up on the state of the coil and from notes in the manual they mentioned about removing 12” of tubing, or he must have been like my bother-in-law and got fed up with changing the coil every time he wanted to alter bands! 

The two coils after a quick clean up, no doubt in the future I will put them to use.

With the antenna originally at 18ft in length I rightly guessed it had been reset as a mono for 20 meters but in its present state it wasn't going to transmit or receive anything. So I took it all to bits, and started from scratch, the coil looked in a sorry state, it had been glued together at some stage and so I removed it altogether since in its present condition it was certainly not going to work. 

After a good clean and checking the rest of the connections I reset the antenna length to roughly 16½ ft and connected it up to my analyser, all now seemed much better with an SWR of 1:1. 

So then I planted the refurnished antenna next to my 30 meter vertical via an old piece of scaffold pole hammered in to the ground. Using the 30 meter ground wires I attached some thick copper wire to the ground plate and I was now all ready to connect to the radio and have a listen on 20 meters. 

You wouldn't believe there are 30 odd ground wire connected to that plate!

Sure enough signals were coming in and after double checking everything was correctly connected I did a quick transmit through the dummy load, everything worked perfectly. Calling CQ I immediately got a reply with a signal report 599 from another QRP station in Italy. 

The HyGain planted next to my 30 meter vertical

Very pleased with the outcome I did some further testing against the 20 meter portion of the cobweb; however the cobweb was definitely stronger no doubt because its thirty odd feet up in the air and clear of all surrounding objects. But never the less it was great to get hold of an old Hy-Gain and bring it back to life!