It’s been a little while since I have posted, and its not because I haven’t been doing anything. I’ve been getting my portable station even more portable that before. Ov er the past 3 weeks where I have had a spare evening I have been putting together a new portable station that is even more lightweight than the previous setup featured in my post on Peter Murrell Reserve. Key to this has been producing a linked dipole.
Linked dipoles provide the benefit of creating a single-wire antenna that is resonant on multiple bands without a tuner by “linking” together lengths of wire with clips. While there is no limit on how many links you make, it may not be practical to make the dipole suit everything between 1.8 and 450 Mhz.
I ended up going for a 5 band antenna – 6m, 10m, 15m, 20m, 40m.
Baluns have always been a bit of a homebrew boogeyman to me, mainly due do what appeared to be some sort of magical winding technique around a toroid. However, given the prices of baluns these days seems to range from $60 AUD upwards, given I have all the parts already at home to make one (“free”), I decided to bite the bullet and learn how to make one.
I’m not going to bore you with the details on how a balun works here, other than to say I think they are useful for connecting coax to antennas. Ladder line, while more efficient, doesn’t have a very good use-case for my applications and good quality ladder line is also expensive and difficult to obtain compared to the plenty of coax I already have available to me.
Shout out to VK6YF whose diagrams for the 4:1 Ruthroff voltage balun were what I used. Some people will be quick to tell me that it was odd to make a 4:1 balun when I am not using ladder line – I agree (and in hindsight should have made a 1:1 balun), but this was about learning how to make a balun.
You can imagine my surprise after being having my build peer reviewed by my good friend Murray that other than a dry joint that was soon fixed, the balun actually worked! to put this in context, two previous attempts at building a balun had resulted in wildly varying SWR and resistive load that on the whole didn’t look much better than just using a piece of wire.
Anyway, now that I know I can build them, I will obtain another jiffy box to build a 1:1 balun for use with my upcoming portable dipole!