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QRP On 160M

QRP with K3WWP - Column # 68 - Let's talk about QRP on 160M. This is a good time to do it. With the sunspots declining and the ionosphere becoming less absorptive of low frequency signals, 160M (and 80 also) will be in good shape over the next three or four years now.

In addition to it being well known by the propagation experts, I can personally attest to the fact that the low bands are best during the sunspot minimum years. All I have to do is look at my statistics for the 160M contests I've entered over the past 10 years or so. A simple look at the number of QSO's here will suffice.

These are my yearly QSO's in the ARRL 160M contest: 1995-251, 1996-250, 1997-128, 1998-75, 1999-67, 2000-22, 2001-DNE, 2002-DNE, 2003-52, 2004-147. Conditions in 2001 and 2002 were so poor I didn't even bother entering. Almost a mirror image of conditions on the higher bands (10,12,15 meters), and inversely proportional to the sunspot number.

I think that establishes my point about when 160M is the best band for the minimal QRPer. Now for the ham with the QRO signal and phased verticals or wire beams, etc., I'm sure there is not that sharp contrast between maximum and minimum sunspot years, but it is a definite contrast for us though.

It takes a lot of room to put up a big 160M antenna that is necessary to do REALLY WELL on this band. Something like a good vertical with an extensive ground system would be ideal. However a full quarter wave vertical on 160M is a very tall beast indeed. Without a loading coil to shorten it, that comes to roughly 130 feet, something just not attainable at the vast majority of ham homes. Of course those living out in the country can probably erect such a monster without much trouble at all. Even with a loading coil to shorten the height, it is still impractical for the city dweller, especially the apartment dweller.

Once we get past the antenna itself, there's the ground system to consider. In order to get the good low angle radiation needed for DX work on 160M, there must be a good ground system for the vertical to work against. A minimum of several dozen quarter-wave radials buried in, or lying on the ground is perhaps a rough minimum figure for very good performance. Not many hams can do that in the limited space they have, again with the exception of those living out in the country.

A dipole for 160M is also a rather large beast measuring in at about 260 feet in length for a full half-wave dipole. Not only must you consider the length, but the height as well. You must get it up in the air to get it to emit low angles of radiation needed for distance work. Otherwise all your radiation will be at high angles. This means that your signal will not travel very far before it is refracted back to earth through the ionosphere. You'll have a good signal out to a few hundred miles from that first 'hop', but to travel further requires additional hops. Each hop involves a refraction and a bounce off the earth that involves signal loss, so if you start with 5 watts, after multiple hops that 5 watts becomes much less.

A good compromise is the inverted L antenna with both a vertical and a horizontal portion that makes it neither so tall nor so long. The vertical portion does the main radiating so the angle of radiation is low. It still requires a really good ground system though.

But while you need an antenna like those described above to do REALLY WELL on 160M, what I said in my last column about simple antennas still holds true here. You can do OK on 160M with much less. Especially in contests where you will be working the 'professional' contest stations who are using the top-notch antennas and special receiving techniques. They can copy that tiny weak signal of yours where the normal ham station can not.

With my random wire in the attic, which has been documented in previous columns and on my web site, I've worked 41 states on 160M which I don't think is all that bad. I probably will make it to 48 states some day since I have worked CA and OR, but KL7 and KH6 may be out of reach. I only have 3 countries (W, VE, VP9) on 160 meters though. That's because of two reasons. My high angle of radiation, and the high noise levels on 160M down in the Caribbean area in which are located most of the closest DX countries I might be able to reach.

It's a fascinating topic, and I could go on, but space does not allow. By the time this reaches you, it will be well into 2005, and the good 160M winter season will be over. However it's not too early to plan for the 2005-2006 160M season which should be even better. Visit my web site at http://home.windstream.net/johnshan/, check out the new NAQCC web site at http://naqcc.info/, email me, or write John Shannon, 478 E. High St., Kittanning, PA 16201-1304. Till next time 73 -30-