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 Â£2) so we decided to test how well the unknown mix ferrites worked. Continue reading “Using cheap ferrite beads for an LFA choke”
This is a simple modification that takes around 5 minutes but makes a big improvement to the already great TM-V71. The fan on this radio is very loud and runs at full speed from the moment you press the PTT then stays on for a few minutes after you release the PTT. This isn’t a problem in a mobile setting where there is usually more background noise but it is very loud when using the TM-V71 in a quiet home shack.
Continue reading “TM-V71 fan upgrade”
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”
I started to work on a simple APRS transmitter today so that I could use it as a antenna test bed for Project Swift.
It was very simple to build using only an Arduino Uno, a Venus GPS receiver a Radiometrix HX1 module (on 144.800Mhz) and an SMA PCB socket.
The completed board looks like this…
After playing around all day with the APRS message format, I managed to get it working and updating to aprs.fi via my own igate.
Next up will be a test with it installed in the car.
So I took part in the 2M UKAC again last night. I wasn’t expecting much as I was going to use the collinear on the side of the house but at 17:30 I decided to go outside and put up the 2M beam that I had just acquired through a swap.
Continue reading “UKAC March 2011”
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”