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Monday 23 September 2019

My journey to finally getting on the HF bands from home and the Slinky antenna idea

With my full licence out of the way I can focus on the other things in Amateur radio I want to do, this includes operating HF from home (without upsetting the neighbours of course), a thin wire antenna strung in the nearby trees should do it (with an ATU preferably fed with balanced feed up to the shack window then a coax into the shack (may need a second CTC-50)) though other antenna ideas are out there and one that would probably attract people into the hobby, and show you can make an antenna out of almost anything, is the Slinky antenna, which has been proven to work though Slinky toys are usually made of cheap steel so don't lend themselves to great antennas and would corrode if left untreated outside, in general this should require at least two Slinkys attached to a dipole centre and preferably fed with 300Ω or 450Ω ladder line into an appropriate balun (just to eliminate common-mode currents on the coax feeding it as this may pose interference and tune problems), suspended taut with a piece of rope running through the Slinkys as they don't lend themselves to staying suspended horizontally.

With no HF set it is not possible to actually test this out, though some say it could work for 80-meters it may work better for higher up, say 20-meters but nothing to stop adding more Slinkys to make it longer and closer to resonance at the lower frequencies, which would require longer ropes for holding it vertical, however the real added bonus is that this makes a crude portable antenna that can collapse down to a very small size indeed, and also extremely cheap to make.

The Slinky antenna is listed in the Stealth Antennas book by Steve Nichols G0KYA, though I first had the idea when I saw Slinkys in a local branch of Boyes (a chain of cheap department stores in the North of England) before I read it in the book (which I purchased to come up with a good way of getting on HF without drawing too much attention, though a Slinky might draw some attention though a theory is that if an antenna is mounted high up and no one looks up it goes unseen and unnoticed for some time (until of course RFI becomes an issue which as responsible Amateurs we are obliged to resolve as part of our licence terms), and hiding a wire antenna in trees might work better though I do want to try out the Slinky idea anyway because I am all for experimenting.

The only thing I don't know yet is how bad the noise level around here is on the HF bands, there are no houses with solar panels on my street at present, but there are plenty of houses and three other identical blocks of flats which means potentialy battling the dreaded PLT and nasty electronics that have had all levels of filtering removed from production models, however when I checked the noise floor on 11-meters it was not dire (about S4 at worst) and my wife and I were able to use the band to communicate successfully during her visit to the UK while I was at work or otherwise out in the car while she was at home, hopefully I have that same luck on HF no matter what antenna I use.

The biggest concern I naturally have is causing RFI to neighbours, and potentially my own gear, so I plan to from the start keep a log of all my transmissions on HF, I rarely do this for 2-meters because FM is usually benign and at worst generates a buzz on things, my poorly shielded computer speakers in my shack being a good example of this, also I plan to do plenty in the way of RF housekeeping so that any RFI issues should not occur, however with modern electronics that are not adequately immune then even this may not be enough however I still plan to operate until such times as I am told by neighbours that I am causing them interference, and it is for this reason I intend to keep a log to make sure that the neighbours are in fact telling the truth (I have had an instance already where my 10/11-meter antenna on my car has been complained about, to me fortunately, for causing TVI yet it was not connected to a radio at the time, my mobile antennas do get noticed, though the person that made the accusation had no understanding of radio at all, all I could do was brush it off and tell the truth, that the antenna was not plugged in and I was not transmitting), filtering out the true interference reports from the false one will always require a log.

The radio is the next hurdle, should I make it to Newark this year (which has been in doubt since I was told I could not have the weekend off), I will see what I can find there, if not the other radio I have in mind is the µBitX from India (which is now into version 5 after the American scaremongering about spurs forced the designer to redesign part of it) which is just a shade over £100 and can do up to about 10-watts on 40 and 80-meters (my two main HF bands of interest though I may want to operate top band later), though I am tempted to measure this, there are other "cheap" HF rigs out there such as the Xeigu radios from China (though the price point of some of these is not really cheap) and the unauthorised Chinese copies of the mcHF (which I would never buy as the designer of the real mcHF put a lot of work into it and the real thing would be my preferred choice could I afford it right now), though with the µBitX you get satisfaction from assembling the non-assembled parts and can design it into a case of your choosing (you get the same satisfaction assembling the genuine mcHF or even a transceiver of your own design if you're truly inclined), but I will see what happens there, or if all else fails I could borrow the Kenwood radio from the club as we use a Yaesu rig for HF operation at the club, though I'd need to borrow the manual tuner as well as that is another hurdle to overcome in the grand scheme of things.

I look forward to operating HF hopefully with a mix of portable and home operations because I want to be able to show to the world that Amateur radio is actually exciting and still relevant in the 21st Century, and I am hoping to sit down at some point and actually start teaching myself Morse code properly, will have to listen to some as well as practice sending it to get tuned to it (no pun intended).

73 de M0WNU

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