Project 11: Better quality 150MHz Dipole

                       This is essentially an upgrade of project 7 Airband Dipole . I thought the results from that roughly built, simple,"thrown together" Dipole were encouraging enough to build something more permanent. Once again, the materials were cheap : a 3 way junction box, 1 metre length of aluminium tubing, 8 cm of old nylex garden hose and silicon sealant.

Hose sections used as packing

                       The tubing came as  1 m length so i cut that in half. The tubing does not fit snugly into the "T-piece" so some packing is required. In this case, 2 bits of old garden hose cut into 4 cm sections and then cut down the middle, opened up and pushed onto the tubing which then fits nicely into the box. The bits of excess hose are then trimmed off.

Packing trimmed and holed drilled

                       After that, the holes are drilled for the coax fittings. The standard nuts, bolts, washers and auto-electric crimped type connectors are used. The box cover plate is screwed back on, and silicon sealant is applied just about everywhere.

co-ax fitted

cover replaced

mounted

                       Once that had cured, it was mounted in place of my weather station which despite being guaranteed to be made of U.V. resistant plastic, is falling to pieces after 5 years in the aussie sun. This time the antenna is mounted a wave length away from the mast which i noticed is the practice used on commercial VHF antennas.
                       Unsurprisingly, this gem of an antenna performs far better than its predecessor. I have really enjoyed the progress of these 2 builds. It started as in idea i saw on the web, then to a rough prototype for proof of concept and now the final build. A very simple, top performing antenna build, enjoyable from start to finish.




 

                            

My 3 Point approach to tracking local aircraft

                    I thought i would quickly show how i'm able to track aircraft in southern airspace. I now have Plane Plotter and ADSBscope set up properly so i'm able to get information from both ACARS and ADSB and plot them on maps.
                    Firstly and most basically i can hear air traffic conversations:

voice transmission on SDR#

                    Second, Plane Plotter takes data from ACARS transmissions, logs and plots them on local maps (which are a pain in backside to implement). However, because aircraft are moving so fast, it isn't always possible to receive locations consistently.

message content

location data showing some locations missing

plotted onto local map

                    Third (to cover data gap in ACARS) i use ADSBscope which is VERY dependable in the amount, range and frequency of data sent.

ADSBscope showing data missing from ACARS

                    So when i sit down in front of the pc and laptop, it's a great feeling to know i have all the bases covered. I never thought "plane spotting" would be of any interest to me, but with the right tools, i always have something to do when HF conditions aren't great.




 

Project 10: A quick extention to my desk

             I recently got a laptop so i have a dedicated pc for all my radio software. The problem was that i had no room left on my desk. The solution? $20 spent at the reject shop got me a bookshelf that would be ideal. All i really needed to do was cut it down to size, fit a bracket so my dog won't move it in her quest to lean on everything i own. Mrs Phil even chipped in and surprised me with some black and silver containers for the shelves.

almost looks like it was part of the desk

everything at my finger tips

 

Project 9: A coax collinear antenna for ADSB

           Another VERY quick antenna project to enable better reception for my ADSB system. I used the method described here: http://www.balarad.net/ by Dusan Balara (thank you!).
           The antenna is simply 8,12 or 16 (i went for 16) 116mm (plus 50mm) sections of coax, with each end of each section stripped allowing 25mm of solid core which is then inserted between the outer jacket and braid of the next, giving it an offset appearance. A small piece of plastic is placed between each of the core sections to avoid shorting. The joins can be taped if you're in a hurry, but i love using heat shrink and it restricts movement better.

16x116mm sections

plastic squares for insulating the cores

keeping the cores insulated

a small section of the completed 2metre long collinear. note the off center appearance.

The finished product (center) , added to my growing farm.

           A 2 metre section of sparkies conduit from bunnings is used to house and protect the collinear, seal the top (i found an old cap from a roll of copper that a plumber left behind), seal the base and up she went.
           This was the fastest of my builds to date (taking just over 45 minutes) and the cheapest. 2 metres of 75ohm RG6 cost $2, 4 metres of conduit ( i will use the other 2 metres on my next project) cost $4. I don't know how much this antenna would cost to buy, but i'm certain it won't be $6!!
           Apparently this antenna is said to have excellent "horizon" qualities, and this is indeed the case. In testing this evening, i am receiving aircraft far earlier and losing them far later than last nights session with the discone.

Using the RTL 2382U as an Automatic dependent surveillance-broadcast (ADS-B) receiver

          Ive been making good use of my RTL to receive ACARS with ACARSD recently and was looking for something a little more technical. Some googling led me to ADSB# which in turn led me to ADSBScope. Well, i spent 6 frustrating and ultimately fruitless hours of my life trying to get ADSB# to work, no matter what i did, even down to uninstalling the drivers, it just would not work. Then i found RTL1090. What a joy this piece of software is to install and use! RTL1090 is the necessary link between the dongle and ADSBScope, tuning to 1090MHz and providing the data for ADSBScope to plot.
         Both programs are well documented on the net and simple to install. At first i was dubious as to whether the dongle would actually work in the GHz range. Anecdotal evidence says it will, but each dongle seems to have its own intricacies. Fortunately,  the RELWITHDEB zip i downloaded contained a test file that indeed showed it could. (how much more can this great little stick achieve?? actually, i have read that it is possible to modify it to receive below 30MHz!!...but thats for another day).
         The following shots are taken just after i got it running and i have spent a very enjoyable day watching my "RADAR".

RTL 1090

ADSBScope

2 aircraft plotting

         

Project 8: Turnstile Antenna for Weather (WX) Satellites

                           This turned out to be quite quick (about 4 hours) and easy. I used VK4LHD's construction method. The materials were under $50.

Only 8 parts

                           The aluminum tubing is cut into 6 lengths : 2 x 1200mm for the base reflectors and 4x 520mm for the top elements. These are inserted into a 40mm diameter/1000mm long pvc pipe with 1 hole drilled at 520mm  from the top and the second hole 550mm from the top and at 90 degrees to the first hole.

The 90 degree holes

                       

Bottom section

And top section done

The 4 way junction box is mounted to the top of the pipe by inserting a block into the end and screwing the junction box to it. The elements are drilled at one end to accomodate the terminals for the coax cable harness. I drilled 2 holes in the sides of the junction box to allow an access feed point for the coax.

The drilled elements

                         

The finished product

The turnstile mounted

Thats basically all there is to it. On the first pass of  NOAA 19 today, the image quality is vastly superior to any antenna i have tried before. Some more fine tuning and i should have some decent images. Here are some NOAA 18's after a bit of tinkering with WXtoIMG:

NOAA 18 26/5/2013*

NOAA 18 26/5/2013*

                                                 * Received with the RTL E4000 and SDR#                      

 

Project 7 : AirBand Dipole

Another rainy day project! Recently, i have been making great use of my RTL Dongle with SDR# to cover the airband as well as local signals in the 118-170 MHz range. The problem: my Discone did not do a good enough job. The solution: a quick build dipole.
In keeping with spirit of this blog, i sourced the parts from an old tv antenna and a bit of pvc pipe i had left over from the multiband longwire build. The 2 elements were cut to 58cm and fed into the pipe...and thats it! Easy peasy.

The "new" Dipole mounted

SDR#

A welcome addition to my antenna family

The results are a fantastic improvement on the Discone. I'm picking up airports and aircraft  from all over the state as well as interstate. The signals are clear, particularly from the aircraft. I'm happy now that between both SDRs, i have HF and VHF Aero covered. As a test, i followed a Qantas international flight (listening on VHF) from take off, then on HF as it left our shores and ultimately tracked it using HFDL as it flew out over the Pacific.No shortage of interesting things to listen to once the cold days and nights really set in.Build time: approximately one hour.

Budget RF amplifier

What do you do when you need to give that weak signal (or in this case all weak signals) a boost and want to spend no money? Well in my case, i had a handful of components, no circuit board and not much solder. I flicked through some of my old books and came across an easy design that would suit perfectly. I drew this diagram using an online designer, so its not perfect, but you get the idea.

 Component list: RESISTORS :  1 x 1.2k, 1 x 47k  CAPACITORS: 1 x 10pf  ceramic, 1 x .001uf  ceramic  DIODE: 1N4002  TRANSISTOR: NPN DS548, SWITCH x 1, BATTERY CLIP x 1 and 9V BATTERY x 1.

 The components were scavenged and i had just enough solder to roughly attach "legs" to them. They are then connected and mounted on a wood base via the same method i used as a child...screws and washers! The end result is not pretty, but signal increase from the multiband and pre-selector is fantastic.

RF amplifier working with the pre-selector

                   

Project 5 : N4UJW Multiband longwire

I found this antenna some years ago and i always wanted to have a crack at building it once i had the time and materials. The design i followed is by N4UJW and can be found here :http://www.hamuniverse.com/shortwaveantenna.html
The original design required speaker line or even fencing wire as options. I went for plastic coated clothes line wire as i needed something more durable that would stand up to the winds we get here. So, 140 metres of line divided thus: 1st element: 43.891 meters (90 and 31 M bands), 2nd element: 36.149 meters (75 and 25 M bands), 3rd element: 28.011 meters (60 and 19 M bands) and 4th element: 24.171 meters (49 and 16 M bands).

original design

The mounting was fairly straight forward with the exception of the insulators/spacers that i just could not get to function correctly. As stated in the image, the premiss is that each element will support the one above. In practice, no matter what material i made them from (including bamboo), they offered no support. In the end i reverted to tying each element individually to the support mast.

Mounted on the mast, showing the co-ax/element harness

I have been testing this antenna for a couple of days now and it beats my old faithful longwire hands down. It is used in conjunction with my homebrew pre-selector (see previous project) and a 9 volt, single transistor RF signal booster circuit i built. This antenna is perfect for the utility monitoring and signal decoding i do with my SDR and programs. Build time was a couple of days.....on and off.

Second project: Microphone Boom

I had this idea last week and it turned out to be quite quick and easy. I went Bunnings and bought an angle poise desk lamp and then went to Dick Smith and bought a 600ohm vocal microphone. First step was to remove the lamp components and fit a microphone clip. Secondly, drill a suitable hole in the shelf to seat the stand and thats it. $50 in components and 10 minutes adapting and fitting and i have a quality desk microphone and boom that takes up almost no space and can be extended to suit the operator.

The first of 2 Projects this week

I haven't had a lot of free time this week, but still time enough to get 2 projects done. The first was a simple shelf to give me more access to an increasingly cluttered station.

Cross Member For Mast (a Sunday arvo project)

It was a glorious Sunday afternoon so i decided it was time to add a cross member to one of my masts in order free up another. Nothing technical here, just some mast brackets and a length of light pipe cut to a suitable length. Now i have the weather station and the Discone perched on the spar and a spare mast for my next project.

Pre-Selector for SWL

    Here is a "homebrew" antenna tuner i made as a weekend project. The design is by brian Carling and was published in SWL Echo, December 1991.