The contest club I am part of uses 2M Loop Fed Array (LFA) yagis for their QRO station. It’s always been advised to use a choke of some sort as close to the feed point as possible to prevent stray RF traveling back down the outer of the coax and into the station. The cheapest way of doing this is by creating a coax choke using 2 to 3 turns of coax around 2″ in diameter but this is also quite messy and risks fracturing the center conductor or foil in the feeder.
There are several commercial ferrite chokes available which replace the messy coax choke and one of our members has a large stock of unknown mix ferrite beads (which can be purchased in a pack of 5 for under £2) so we decided to test how well the unknown mix ferrites worked. Continue reading “Using cheap ferrite beads for an LFA choke”
I did this repair many years ago after the mounting failed on the X-300 (original single bold stub mast) which allowed the antenna to sway. It gave a few more years of service after the repair and mounting modification and was only taken down to be replaced with a new X-510 which has the same mounting modification.
The X-510 has been up for many years with no issues despite being battered by the winds and salt coming off the North Sea.
Continue reading “Diamond X-300 repair”
I love a good T2FD antenna and have built a good few. There’s a few variations but they all work well and are easy to construct. I’ve been asked a few time about the length and spacing so I made a small Excel sheet to work it all out and provide data for the 3 most popular variations.
Free free to download and use. The sheet is protected to prevent the formulas from getting messed up but if you would like to experiment with alternative formulas then please just contact me for the password. All I require is for my original credit to remain on any derivative works.
M0LMK T2FD Calculator
I usually get static build up on my HF doublet due to sand particles (I live above the beach) in the air so have been thinking about a way to bleed off the static and provide some protection to my TS-590SG. After a little research, I came up with this, a lightning arrestor/static bleed device that provides a permanent path to earth for DC whilst allowing RF to pass and providing protection from nearby lightning strikes. Continue reading “Ladder Line Surge Suppressor”
A common fault on the SGC range of antenna tuners is a reduction in receive performance as they get on in years. This can be attributed to contamination on the relay contacts since SGC stoped using fully sealed relays. Any small condensation inside the tuner makes it’s way into the relays and causes contamination on the contacts as they are hot switched. The best thing to do is to replace all 26 relays with new units…
Continue reading “SGC-230 relay replacement”
I’ve got an ever increasing noise floor at my QTH so I thought I would try an active HF loop to see if I can null out the worst of the noise.
I found a simple design on-line and used it as the basis of my loop. The original site unfortunately no longer exists but I did manage to save the design here. Continue reading “Active loop antenna for HF”
Another part of my antenna experimenting equipment. A simple ugly choke for HF made with 30 turns of RG213 coax around a 4″ plastic pipe.
I needed a 1:1 balun to use with my home brew doublet but I needed it to go between the ladder line and the SGC-230 tuner so it needs to have stud terminals on both the input and the output. I took a look around and decided that making one was the best option.
It’s made using 11 turns of figure 8 twin lead on two stacked FT240-43 cores. See the pictures below…
Continue reading “1:1 BALUN for ladder line”
I like to take part in the 2M UKAC run by the RSGB when I can so I made a simple, lightweight 5 element yagi that I can put on my 10M mast and use portable.
Continue reading “Portable Yagi for 2M”
After deciding that my doublet works better than the multi-band vertical that I built from a 10M fishing pole, I decided that I wanted to try a mono band vertical.
20M seemed the obvious choice as I could use the 10M pole to create a 1/4 vertical with radials.
Continue reading “20M vertical”
I’ve had a vertical up for a while now but it was just a quick and messy install to test the results.
I have been pleased with them so have decided to have a go at installing the vertical in a better position with a more permanent solution…
Continue reading “Homebrew multiband HF vertical”
So the weather station has been up and running for a while now but something has been bothering me. About twice per hour I get a “lost sensor contact” message from the software. Occasionally, it looses contact for a few hours at a time before it comes back.
Continue reading “Lost sensor contact”
Operations this weekend are taking place thanks to this impressive vertical.
Continue reading “Tempoary vertical”
Following the death of my cheap fibreglass tri-band collinear, I decided to have a go at constructing a simple dual band antenna for use at home.
I was looking for something that was vertical, omnidirectional and with good gain that I could make quickly and easily. The answer came from Sean, M3FVB in the form of his excellent article on building a 8db collinear.
Continue reading “Simple stacked J-pole for 2M & 70cm”
I have an SGC 211 ATU. Its a great bit of kit but I wanted to mount it outside.
A simple post for a simple job so here are the pics…
Continue reading “External enclosure for ATU”
I love a good Yagi. I also love folded dipoles. So why not mix the two up and make a nice Yagi driven with a folded dipole?
This 12 element monster is easy to make and produces a theoretical 12.75 dBd gain. The dimensions were calculated using this tool. The details are: Continue reading “12 Element Yagi for 70cm”
After making a batch of nice folded dipole elements on my diy jig, I needed to work out how to mount them and feed them with 50 Ohm coax. The feed point impedance should be 200 Ohms so I needed a 4:1 balun.
Continue reading “4:1 Balun for folded dipole”
I’ve got a strange fascination with folded dipoles. Single or stacked and phased, I just can’t seem to shake the need to build one from my head. So toady I have made a simple jig to help bend up a batch of folded dipoles.
Continue reading “Folded Dipole Jig”
Having just purchased an Eton G3 radio I wanted to get into Short Wave Listening a bit more. I am generally interested in NAVTEX, DGPS signals and Numbers Stations but the internal G3 bar type antenna just wont cut it.
I initially tried to just throw up a length of wire, stretch it out across the garden and straight into the G3’s ext ant jack (which is a 3.5mm mono jack by the way). It kinda worked and I could hear a few more stations but it also pulled in a huge amount of noise generated by the nearby houses and electrical junk.
Continue reading “Building a Longwire antenna”