Screen shots: EFHW, vertical, mini-beam vs the quieter doublet in lower part of the waterfall

   

VY1GS Gord

Icom 706 Mic/data Switch (click on small pictures)
Full pdf document - 6 pages, 10 pictures, schematic

Found an old construction box (5 ½ x 3 x 2) I had and resourced it for this project. Used 2 male to chassis-mount female Cat 6 connectors (cut off the male end) as the microphone and Winlink plugins. The color coding for the Cat cable ending on the Icom microphone does not conform to standard color coding of Cat cable so make sure the pins follow 1- through -8.

I purchased four 12 VDC relays and soldered diodes across the coil to suppress the negative excursion of DC when deactivated and disc capacitors to suppress any induction. As far as supplying power I decided just to use a stereo speaker wire block --- any bared wire will fit from whatever you want – cigarette lighter for mobile use, the 12 volts used to power the radio, a small battery pack.

It defaults to the microphone plug when de-energized (or just no power to operate) by virtue of the pins you assign on the relays.

- Gord

VY1BG Geoff

Updated Solar Panel (click on small pictures)

VY1BG updated the control mechanism to track the sun. A battery screwdriver with 3 AA batteries moves the solar panel, the controller powered with AA batteries activates and controls direction of panel movement. It is very sensitive and really noticeable on the wattmeter when the solar panel is not pointing at the sun directly.

      

VE3XCC Charlie (VY1CC)

2M YAGI-UDA For Fringe Area Communications (click on small pictures)

Full document in pdf

The Problem: Access the repeater that is 45 KM away. Bearing is 120 degrees. Some signal can be heard, but extremely noisily, and even 50 Watts into a quarter wave mobile antenna will not bring up the repeater.

Further Analysis: As you can see from this Google Earth elevation profile I do not have a clear path. However with diffraction effects, I should be able to communicate. Diffraction will, however, create significant additional path loss, especially ontransmit.

 

Time to try a Yagi: A bit of number crunching, and I thought I’d start with a 6-element design. EZNEC suggests 11.5 dBi improvement (see below); design includes 1 Reflector, 4 directors, 1 driven element. I found some 13 mm flat stock aluminum 3.5 mm thick in 8 foot lengths and some 8 foot channel stock for the boom as well on price reduction at Princess Auto (total cost $16). I used VK5DJ’s Yagi calculator for everything but the driven element matching

The matching problem: Measuring with the NanoVNA showed feed point impedance of about 22 ohms resistive. This suggests the resonant length is right, but we will need to raise the impedance to 50 ohms. My first thought was a transformer. Turns ratio would be 7:5 and would also take us from unbalanced to balanced. Unfortunately my junk box did not have a suitable toroid. This might be a future modification, especially if I measure a lot of RF coming back along the coax. Next thought was a beta match. This U shaped wire about 5 inches long typically corrects the impedance of Yagi antennae, however my measurement showed this made things slightly worse at the frequency of interest. I then twisted it into a single turn coil and re-measured – impedance was lower again Clearly I need a capacitive element, so I cut the wire in half and pushed the two pieces close together in parallel. This improved thing but not quite enough. I then bent them over parallel to the radiating element – still more improvement Finally I moved them as close as made sense and the match was excellent.

The Result: I was able to bring up the repeater with a Baofeng UV5R (approximately 5watts). I logged into the repeater with Echolink, and was able to send andreceive both directions. This brings talking to yourself to a whole new level!

VY1BG Geoff

Updated Solar Panel (click on small pictures)

VY1BG updated the control mechanism to track the sun. A battery screwdriver with 3 AA batteries moves the solar panel, the controller powered with AA batteries activates and controls direction of panel movement. It is very sensitive and really noticeable on the wattmeter when the solar panel is not pointing at the sun directly.

      

VY1KX Allen

40-20 Trapped Dipole (click on small pictures)

A multi-band antenna can be built using traps (combination of coil and capacitor) which stop RF frequencies on a frequency the trap was designed for and allow lower RF frequencies to continue along the antenna. Reference & Reference 2 The VY1KX QRP dipole antenna works on 40m and 20m without a tuner, constructed using small diamater stealth wire and pico trap kits (10 Watt rated) and a balun kit from SOTABeams. It works well in campgrounds with a lightweight portable mast from SOTABeams.

"The Sotabeams balun doesn’t have a place at the top for a hook so I added the white plastic piece and the stiff green wire so as to have a convenient way to attach the antenna to my “Tactical pole”. In use, the stiff green wire is just inserted into the top section of the pole." More to come ...

   

VY1GP George

Portable "Station in a Box" (click on small pictures)

Update Aug 13, 2022: exchanged large paddle for a small one, exchanged large ATU for a smaller one, added a solar charge controller, inserted Surface Pro table to run Ham Radio Deluxe, WSJTX and Winlink. Made some FT8 QSOs and a Winlink email exchange via a gateway in San Rafael, CA on 20m.

This inspiration came from testing a portable station on Field Day 2022. Everything fit in a small Canadian Tire Maximum tool box that I had on hand: FT891, 9Ah LiPO4 battery, LDG-Z100Plus Autotuner, watt meter, heavy Belcher paddle, power cables, coax jumper, manuals and notepad. It worked well, except that it took a while to assemble the station and put it away, and was difficult for a new user to get everything packed up in the right spot. Things were left over.

When I realized that the lid can be removed completely by slidng out the rods in the hinges, it provided opportunity for reconfiguring everything. Now very little needs to be removed from the box (just the tuner and the paddles) and only a couple of connections are required to be on the air quickly. A bit of velcro and flexible foam material hold everything in place when packed away and while operating.

The box stands vertically while operating so the radio screen and controls face the operator at a nice eye level. The speaker is unobstructed and faces the operator. A spare battery can easily be exhanged or a power supply connected by changing one Anderson connector. The bits of packing foam can be stored neatly in the paddle's spot while operating. All the radio jacks are readily accessible for connecting a paddle, key, and digital equipment. It is portable, weighs 17 lbs, looks nice on a small desk or a picnic table, and sits nicely on the centre console of my Taurus.

       

VY1GP George

Portable Linked Dipole Antenna: 80-60-40-20-17m
A 100 wt linked dipole antenna was built as a demo for YARA Field day, but was not set up. Materials: bits of 18 ga speaker wire, auto wire bullet connectors. Tested with SOTABeams portable mast, on a tower with pulley, and on 14' 2x3 with pulley with 4:1, 2:1, and no baluns. Fed with coax. Easy to use, very quiet antenna as set up in my front yard. For portable 40-20-17m you can disconnct the longer pieces of wire and leave them at home.Theory On-line Calculator Pictures can be seen in the photo albums.

Update August 19, 2002: A small pulley was added to a 10m Sotabeams Travel Mast to quickly raise and lower the linked dipole to change bands or switch from DX to NVIS. Components: from Canadian Tire - 3/4" pulley, 50' paracord, hose clamps on each mast join to prevent the mast from collapsing on itself, a lightweight Sotabeams 1:1 balanun kit. The pulley was fastened about 3 lengths from the top ( about 25' high).

VY1GP George

Anderson Connector Inline Switch (click on small pictures)After a couple of months searching the Internet for an Anderson inline connector for a moblie/portable unit and finding none, I built two from Canadian Tire parts. The 1st attempt resulted in solder melting the automotive switch inside, the 2nd is a lamp cord switch, and the 3rd is an automotive switch with slide-on connectors. The automotive switch has a red light when "on". Caution: if you try this make, be sure to connect power and radio on correct pins or it will short. The switches were tested with 100 watts power into a dummy load. The exposed wire/connectors were insulated after the picture was taken to show the connections. Jan 15, 2021

VY1RF RAY: DSTAR Pi Zero Hotspot kit

VY1FC Malcolm: QRP Rig, Slinky Antenna

VY1MT Michael, Straight Key

VY1GP George, Straight Key

VY1BG Geoff, 4 way coax switch

VY1MK Mark, 2m and 70 cm

VY1GP George, Flag Pole Antenna

VY1MK Mark, NPOTA

VY1YU Yuuri, 2m J-pole

Tried to build a bottom-fed J-type antenna for 2m, using various buddipole elements, but the shortest elements are just a bit to long to get it to be resonant on the 2m band. So I designed my own pseudo-J antenna with a parasitic element that helps shift the feedpoint impedance to where I want it (near 50 Ohm resistive).

Three pictures show the mechanical structure and three show the results of a sweep: you can see that the SWR is pretty low across the whole of the 2m band. The three sweep images differ only in where I marked apparent antenna resonances (two of which fall inside the band).

SWR Charts

VY1BG Geoff

VY1MK Mark

VY1MK Mark

VY1MK Mark