W8WWV - Sommer XP504

Greg Ordy

#1: Sommer XP504 @ 60'.

Looking up the tower

#2: Looking up the tower.

Antenna work

#3: Antenna work.

XP504 Front Elements

#4: XP504 front elements.

MA550 Winches

#5: MA550 winches.

Diamond V2000A on Chimney

#6: Ground plane Vertical.

My Sommer XP504 antenna has always exceeded expectations. My first expectation was that I could get good performance on the historic bands, 20, 15, and 10 meters, and the WARC bands (17 and 12 meters). As best as I can tell, and it is subjective to be sure, the XP504 performs well on all of those bands, 20 though 10 meters.

In the summer (June) of 2000, with the sunspot cycle peaking, I decided to get on 6 meters. It seemed as if a few Yagi elements at 30 feet would make a good antenna. I decided to check the Sommer antenna web site to see if they had a 6 meter product. Lo and behold, they had a 6 meter add-on kit for my existing antenna. I did not need a second antenna, second tower, or second rotator. I added their 6 meter element, and have enjoyed many openings ever since.  20, 17, 15, 12, 10, and 6 meters, all from a single antenna.

When I first assembled the antenna I added their 40 meter coil, which is designed to provide 40 meter operation, not in what I would call normal Yagi mode, but as nothing more than a lot of metal resonant on 40 meters. While it did indeed resonate, I found that it was not as good as any other 40 meter antenna I had. When I finally added a pair of phased delta loops for 40 meters onto the same tower, I removed to coil in order to remove any nearby (undesirable) 40 meter resonance's.

Sommer also sells a 30 meter antenna option. I do not have any experience with it.

Antenna assembly took about 8 hours, spread out over 2 days. The antenna is well-built, and moderately heavy, approximately 70 pounds. The main boom is actually two rectangular tubes held parallel by the element to boom mounts. The Sommer design does not use traps or coils, and all 20 meter elements are full-size and driven. My antenna uses three 20 meter elements. Versions are available with four or five 20 meter elements. Please visit the Sommer web site for more details. According to the Sommer information, the last digit of the antenna model indicates the number of bands available to the antenna. I have 6, so perhaps I should call my antenna a Sommer XP506. Some other antenna measurements are on another web page.


Picture #1 shows the XP504 on top of my US Tower MA550. The MA550 is a tubular crank-up tower that is 55 feet tall. I also use their tilt-over option, which allows me to do all antenna work at ground level. My rotator is the Yaesu G-800SDX. The transition between the tower and the antenna is made with what I call the Rotator Cage, described on another web page. In the picture, the wires and ropes that visible are part of a 40 meter phased delta loop antenna. Adding up the base,  the tower, and the rotator cage, my antenna is at the 60 foot level.

Picture #2 is taken at the base of the tower, looking up. On the left, you can see the optional arms that provide a standoff from the tower for the feed and rotator cable. The 40 meter delta loops are again visible. The front of the XP504 is on the right. The large number of elements are basically either driven or parasitic elements for the different bands.

Picture #3 shows the antenna tower cranked down, and tilted over. I do confess, it takes about 200 turns on the two winches to bring the antenna down. You'll break a sweat while doing this, and a bigger sweat getting the antenna back up. But in return for this exercise, I can work on the antenna (and rotator) while standing on the ground. This has been a great improvement over trying to make adjustments on an in-place antenna.

Picture #4 shows the front of the XP504 at ground level. Before I tilt the antenna over, I have to make sure that it is pointing at 230 degrees. This direction coupled with the tower base orientation means that the antenna elements tilt over parallel to the ground. The lowest to the ground element is the 10 meter element. If you look closely at the larger picture, you can see the 6 meter element, which is on the opposite side of the boom from the 10 meter element. Above the 10 meter element in the picture are 15, 17, and 20 meter elements. The white box holds a balun which goes between the single feed line and the antenna elements.

Picture #5 shows the two winches on the tower. The left winch raises and lowers the tower, the right winch tilts the tower over. Right above the left winch, around the tower tube itself, is a collar that holds the tower upright, regardless of the tilt-over winch. The collar is removed when you want to tilt the tower over. The tower base is several yards of concrete going down almost 6 feet. A rebar cage is embedded in the concrete for added strength. Four 1 inch diameter bolts come up through the base, and serve as the mounting point for the tower base.

Six Meters

With the sunspot cycle peaking, I decided to get on 6 meters. As described above, I added the Sommer 6 meter add-on kit in order to get my XP504 onto 6 meters. The claim made by Sommer is that the XP504 with the 6 meter kit provides performance roughly equal to a 3 or 4 element monobander. I have yet to really check into this claim, but I do notice significant front to back (F/B) ratio on 6 meters. It feels like a Yagi. Someday, I hope to make better measurements of the 6 meter performance, but I am more than happy with the Sommer solution.

Even before I added 6 meters to the Sommer, I had a vertical ground plane strapped to the chimney that provided 6 meter, 2 meter, and 440 MHz operation. The vertical is approximately at the 35 foot level.  It has been my experience that it is very useful to have both a Yagi and vertical antenna on 6 meters during openings. For local work, and double hop E skip, the Yagi usually is the best antenna. Single hop E, however, is often times stronger on the vertical. In addition, the vertical does not need to be rotated, so there is no delay is being ready to use it. It is a great spotting antenna, listening in all directions while I rotate the Yagi. I suspect that the Yagi will be the best antenna for F-layer skip, but I have yet to experience that propagation mode.

Picture #6 shows my Diamond V2000A tri-band vertical. It covers 50, 144, and 440 MHz. I did find that I could not tune it down to the 50.125 MHz DX area, so I always use the tuner in my ICOM IC-756PRO. This is the antenna that I also use for 2 meter packet (DX cluster).

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Last update: Wednesday, October 09, 2002 06:57 PM
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