OK, serious preppers: Time to pay attention because George’s Radio School is now in session.
At this point, a number of ham radio operators will look at the antenna to the right and proclaim they know all about it and then skip on to the next article.
In point of fact, however, real DX (dx being short for long distant) reception, is much more of a skill-set than most hams will admit.
Sure, the big electrically-lifted 52-feet of tower, with 12-feet of mast atop that seems like it would be an ideal off-the-shelf *(if you get it installed – we did our own) solution. Had help mixing 130 bags of concrete, though.
But, the real secret of hearing “far-away” (DX) stations is much less in the size or height of the antenna. It’s in mercilessly tracking down local noise sources.
Finding noise has been a life-long case of solid detective work. Shortwave (and high-frequency 1.8 to 30 MHz) ham radio listening is fun but THE indispensable tool for noise-finding is a cheap AM radio tuned to the top of the AM band – about 1600 KHz on the dial.
With this tool, you can wander around, holding it up to various wall-wart (plugin chargers) and light dimmers and so forth until your find the source of local noise.
Once you find all the noisy dimmers in the house (most can be fixed for listening to shortwave by simply turning them off) then it’s on to the rest of the neighborhood.
Power poles (if you don’t have underground wiring)_ can be a nightmare. What happens is a little dust accumulates on the top of high-voltage distribution transformers and then here come the occasional spars. Which, by their nature are broadband, so there’s goes everything from AM up to the FM band. FM is more noise-resistant because of the technology. (A ratio discriminator instead of an amplitude detector if you’re deep into the electro-woo-woo of it.)
Even around the ham shack there are hidden noise gremlins. Take that big tower. Until last year, the coaxial cables and rotator control cables coming down from the top went at a right angle to the shop 8-feet off the ground. Looked nice and strack.
I could be heard anywhere on Earth under even marginal conditions. 1,000 watts and a big beam…oh hell yeah.
But, noise level was high and since it went away at night, I figured it might be “common mode noise” from the nearby solar charge controllers. Solved that problem (by rerouting wires to the shop/office) and suddenly receiving became remarkably good.
Hams will be interested that the induced common-mode voltage was cured by moving the feed lines off the tower at a 45-degree angle. This took the closest approach to the solar power center from 2-1/2-feet to about 14-feet. Since radio is ruled by the inverse-square law (double the distance, halve the power) and I got two “halvings” – the noise dropped to a quarter of its previous (annoying) level. Tossed on some clamp-on ferrite noise suppressors and good to go.
From there, the next problem was reducing noise picked up by the surface of the coaxial cable. This was handled by installing an assortment of additional ferrite bead noise suppressors on either side of the cable run involved.
Things verged on excellent. For the past year, when I hear a station like LZ920MCL on the air, it’s usually by design, not a cloud going over, which use to drop the output of the solar panels, which in turn reduced the charger amperage, and that in turn reduced the noise…..
By the way – even if you are a ham – I’ve never gotten deeply into “running down awards.” Like that station in Bulgaria – it is part of their All Saints contest. (Talk to the key cities…)
I’ve penciled in a run at the Enigma Reloaded International event this year. Because yes, Morse skill is really something cool to learn. Don’t get me wrong, a chat with the Space Station is fine, or McMurdo back when. But the UK’s Bletchley Park Radio Centre? You know what that was during WW-II, right? Enigma machine cracking.
So… I worked W3ADO on 20 meter SSB Saturday – the US Navy Academy-end of the 2018 Enigma Reloaded contest. (K3LU is QSL manager for the W3ADO end – not sure if that’s on the ham sites, yet.)
“Enough of the War Stories…”
We need to hear things. If the SHTF, radio will be IT.
Winter is when magic happens on the low bands. AM radio at night is just somehow so much more honest than two clicks and a router, right?
You will need a decent AM receiver…and to improve your odds, consider a small external loop antenna if you are space-limited. It’s $35-bucks but something like the Kaito AN-100 Tunable Passive AM Radio Loop Antenna for All Brands Like Kaito,Sony,Panasonic,Grundig and More will work with many sets. Mine has fallen off my night stand a dozen times and still works fine…
The lower shortwave bands are an antenna problem. (This would include the 160, 80, 60, and 40 meter ham radio bands, as well.) Small receivers are hugely improved with a long wire of almost any length over 20-feet, or so, set up in a long-wire configuration.
Fancy engineering design, huh? That scrawly thing on the right is a tree. (You couldn’t tell?)
Here’s the thing: As wires become longer than one wavelength, or so, they begin to exhibit directivity. So, my current plan is to deploy a receiving antenna set-up like this:
This is what a “Beverage Antenna” set-up looks like. Helps to have 150 feet of open space…our design going in this coming week is about 565 feet…
Some basic secrets to winter receiving only antennas.
- Higher is not always better. Receiving antennas 6-10 feet off the ground work dandy.
- Longer – in the direction of the distance station – is better.
- Even lower is something called a BOG (Beverage On Ground). On receive, the height matters surprisingly little.
- The higher an antenna is, the more noise you are likely to pick up. Noise tends to be vertically polarized.
- Antennas coming into the house should come in by way of coaxial cable with a solid ground outside. Lighting protection is a plus.
- And do read up on common mode noise on Wikipedia.
My buddy of 65-years, the Major, will be coming in this week and we will be installing a mother-giant Beverage array. We’ve been putting up antennas together for more than 50-years…(Elaine and the major’s missus tend to shake their heads in wonder…with that “when will they ever grow up” look when we get into one of these projects.)
[Got so bad once when we were kids that Pappy came in my ham shack and asked “Any idea when this copper and aluminum overcast will be burning off?”]
If you want to attempt to clone what we’re putting in, plan on crossing (right angles) 565-foot Beverage antennas. I’m using Frank (K1FZ) custom-wound transformers for the primary antenna. We’ll wind an additional reflecting transformer. (We don’t want to be accused of being “appliance operators…)
As you can read in his “optimum installation” instruction notes here, you’ll need at least three ground rods for most installations. I’ve mentioned some of this before
The next step is to optimize your wire and height to local ground conditions. When you get it right (for me that’s 565 feet) the antenna’s directional pattern will look something like this when you model it.
Where X is north-south, Y is east-west and Z is uppy-downy.
And when you look at an azimuth plot, that length (565′) over local ground should result in about 15-18 db of front-to-back ratio.
The next step before he arrives is whacking through all this:
Somewhere, about the middle of the picture – way off past the clearing the antenna will pass through – is where the far-end ground rod will be driven. Rain and a tractor bucket and that new Rapco chainsaw blade simplify things.
When done, this kind of antenna is not particularly “hot” – typically -10db from what a dipole would put out in signal strength. But, that’s not what they’re about: this is all about signal-to-noise ratio and nothing else. We can add any gain needed with a receiver pre-amp.
Beverage antennas make lousy transmitting antennas. But, the noise floor? OMG…Amazing. It’s like signals springing out of nowhere.
Sure…enjoy the net radio streams while they’re up. Go ahead, gloat and laugh.
Remember, though, one EMP hit and you know where one of the few surviving radio locations in North America will be located, right? In an after-EMP world, coms will be a real “in-demand” item. Especially if there are no melting-down nuke plants around.
With what we’re calling “Project Big Ears” we will not only be able to transmit worldwide, but our ability to hear news from our worldwide ham radio sources of HUMINT will be enhanced, as well.
Write when you get rich, and put your ears on…