[K6BW] 160 Meter Season is Open
Bill Smith
hbco2 at sbcglobal.net
Sat Nov 7 21:00:55 EST 2009
Building 549 will be open and operating tonight, if you want to try 160!!
73 de Bill, AB6MT
hbco2 at sbcglobal.net
----- Original Message -----
From: David Mueller
To: Members of the Hamilton Wireless Assn.
Sent: Saturday, November 07, 2009 12:08 PM
Subject: Re: [K6BW] 160 Meter Season is Open
Long time lurker here...
160m has been in excellent shape so far this season. Last night the band was in as good of shape as it ever has been. I saw reports from many W6's, some from the Bay Area, who reported working many loud Europeans last night.
The sloping 160m dipole configured at K6BW is a proven winner. Whene I was stationed in Novato, I confirmed over and over again that I was one of the Bay Area "big guns" on 160 with that antenna.
It really works - have fun with it!
73, Dave N2NL/4
----- Original Message ----
From: Bill Smith <hbco2 at sbcglobal.net>
To: HWA <k6bw at mailman.qth.net>
Sent: Mon, November 2, 2009 2:00:29 PM
Subject: [K6BW] 160 Meter Season is Open
Hi All,
Happy Halloween! Hope you enjoyed the parties. As the days grow shorter, 160 meter DX gets better and better and this year may be exceptional. We won't know until next year rolls around (Great DX on 160 generally disappears by the end of January), but 160 seems to be attracting a lot of attention recently. Below are several responses, stolen as usual with no remorse from QRP-L, regarding 160 meter antennas. A little math shows a 160 dipole is somewhat longer than 270 feet long, which is usually something of a challenge for most people's back yards. Yet, we have a 160 meter dipole happily dancing in the wind at Hamilton and we also have the adjacent radio tower which has been just begging to be shunt fed. If you are so inclined, 160 meters is a really fun band and yes, you can make delicious World-Wide DX contacts this time of year. A 160 DX contact imparts a special satisfaction, too.
It's just a thought, if the long nights are piling up, think of all that DX out there just waiting for a call. We're all set up at Hamilton!
73 de Bill, AB6MT
===================================
Rambling Discussion from QRP-L regarding 160 meter antennas:
While folks are looking for a magic reason for the length of a wire for a helically loaded antenna, there almost certainly isn't one.
With a loaded antenna, one must add an inductor to do the loading. The required inductance varies with position in the antenna, due to the differing current in different sections of the antenna. Also, the inductance varies for the inductor with its diameter, as well as number of turns and physical length.
For a given shortened antenna, the inductance required can be computed for various positions along the antenna. Distributing the inductance along the antenna makes the calculation more difficult, but not impossible.
Varying the diameter and spacing of turns in this distributed inductance varies the value per foot of antenna (and varies the wire needed for the inductance). Using larger turns requires fewer turns, but takes more wire per turn.
When all is calculated, it conveniently works out that the inductance has terms of N^2 and radius^2, which means that if you increase the radius by a factor of 2, you get half as many turns for the same amount of wire, causing the changes to cancel each other out.
( More formally, for wire length wl, the number of turns is approximately wl / (2*pi*radius). Thus, the terms in the inductance formula become:
wl^2
------------------- * radius^2
4 * pi^2 * radius^2
which equals
wl^2
--------
4 * pi^2
So, it doesn't matter if you make fewer larger turns, or more smaller ones, the result is about the same. )
Why that particular approximate length of wire? Well my sources indicate that after including all the constant coefficients for calculation of inductance, and integrating the effect of the distributed inductance along the length of the antenna, it just conveniently happens to work out that way.
Alan
wa6azp
Certainly the most common small to mid size lot 160meter antenna is the Inv.
L. Many 160m operators use this antenna and have great success.
I use a 160 meter dipole (slightly inverted) up 100 feet. It is a good
performer stateside (high angle of radiation). Many like to hear results
(ala eham) so running QRP in the ARRL 160m contest 2007 from Colorado I
worked 396 stations and 73 multipliers including ME,HI, AK and a couple of
Caribbean islands.
Lots of great comments and ideas so far on this thread.
My $0.02,
Jay - KT5E
Cal - to answer your question 'What is the best 160 vertical antenna'.
Well something about 130 feet tall would be a good start, fed against a good field of radials!
If that's not possible, then an inverted L - with the vertical portion as tall as one can get.
If loading coils are needed - these are better at the top (for a bottom feed) to reduce the impact of their loss.
As for power the main factor is the matching circuits - making sure they can handle the power (and the peak voltages involved).
Most of us use compromise antennas on 160m. Understanding a few principles is helpful. Taller is generally better, but how it achieves its match is also a factor.
In addition to reading my stuff here, it may be (understatement) worthwhile to read from the experts, like ON4UN. Although he has 'big antennas' he stresses short antennas can still work. In fact he heard my 5 watt signal in last year's ARRL contest !
Note most folk active on this band are running real high power, so don't be discouraged by your competitiveness running less than that. Instead be impressed how far you can work with a modest setup.
73 curt
The very best 160 vertical is a 5/8 wave radiator (about 341 feet) over a football size ground plane. I know this from reports in the 70's of using a radio telescope reflector at the Ohio State University radio astronomy lab by W8LT, the OSU radio club. For a radiator they used a 300+ foot wire supported by a kytoon. It was reported to be the loudest signal from the area. I don't know if they won the contest, but they had one of the most unique antenna "farms" at their disposal.
If you mean what is the best "practical" vertical antenna, that depends on how much real estate you have, how many $$'s you wish to invest, and how many local zoning regulations you need to overcome. There was a fellow who built a 240' vertical, but he actually got a cell phone company to build it, with the stipulation that he could shunt load the entire tower and reserved the very top for amateur antennae. He applied for a dual use building permit, and had the cell phone company pay the legal fees in fighting the zoning board. He (and the cell phone company) won the case.
Many hams will shunt feed a tower of whatever height they have - 50 to 90', sometimes higher. Others will use a more modest vertical.
And, some hams will use a horizontal radiator - at the University of Denver Radio club back in the 60's we had a 80 meter dipole up about 40', fed with homemade 600 ohm feeders. We easily contacted Missouri and elsewhere with about 100 watts (there was some restriction on power for 160 back then - I don't remember details, but I do know we cranked down the 500 watt rig to operate on 160.)
So, "best" is very dependent on the situation.
72/73 de n8xx Hg
Francis Callahan wrote:
> What is the best 160 vertical antenna for both qrp power and hi power Thanks
> Cal KF7ET
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