Wednesday, February 26, 2020

The Ultimax DXtreme

The retired W1SFR
For the past few days, our weather here on the East coast has been excellent nice warm weather (up to +10) with no rain and just great sunny skies. On the second day of this great weather, I decided it was time to put up my new Ultimax DXtreme EndFed antenna. The antenna I have at present is the W1SFR KX3 helper EndFed antenna.  As I have said past posts this is a fantastic antenna, very well built and works as advertised. So why am I replacing this antenna with yet another EndFed antenna, this is a very good question and was answered in this post.
Ultimax size difference
When I took the KX3 helper down I was pleasantly surprised how great the balun enclosure looked. It has been up for over 6 months exposed all kinds of weather and looked as new as the first day it went up. The first step to get the new antenna up was to install the counterpoise that I ordered with the Ultimax antenna. The configuration for my EndFed antenna is the Balun end is in a tree about 25 feet high with the wire extending down to my shed and is terminated about 8 feet above the ground. This is the same configuration I am going to use for the Ultimax antenna as well. The counterpoise from Ultimax antennas consists of a single wire for about 6 feet and then it splits into 2 separate wires. I used a staple gun to secure the counterpoise to the tree trunk.  The only choice I had was to place one counterpoise leg on one side of the tree trunk and the other one on the opposite side. The tree is only about 1.5 feet around so the counterpoise wires are not that far apart. At the bottom of the tree, each counterpoise goes along the ground in opposite directions for about 15 feet.
The Ultimax antenna is rated at 2KW SSB with 14 gauge wire along with a hefty insulator. Since my max output will be 100 watts CW and tops 80 watts DATA the insulator and wire on the Ultimax is a bit too heavy duty. Plus my support at the wire end is a wooden pole that is not meant for heavy-duty support.
Ultimax is up. 
The idea was to use the wire from the W1SFR KX3 helper as so I thought at the time it was only 2 feet longer than the Ultimax antenna wire but very light. I folded over the wire to bring it down to 33 feet to match the Ultimax wire length and check the SWR on 80, 40, 30, 20 17 and 15m both with and without a counterpoise. The results show when using a counterpoise the SWR was not as good as without. I am guessing this is because of the position of the counterpoise, I was running out of time and not able to play too much with the counterpoise. We are expecting a very large snowstorm tomorrow so the antenna play is done for now. I am going to leave the antenna up without the counterpoise attached. BUT having said that the counterpoise is very easy to attach if need be.

Results without a counterpoise:
     Band              Freq           SWR
    80.              4.000.        7.0
    80.              3.500.        8.1
    40.              7.001.        1.8
    40.              7.070.        1.8
    30.              10.100.     3.3
    30.              10.150.     3.3
    20.              14.001.     4.6
    20.              14.070.     4.6
    17.              18.068.     2.5
    17.              18.168.     2.5
    21.              21.001.     1.5
    21.              21.070.     1.5
Results with a counterpoise:
         Band              Freq           SWR
    80.              4.000.        6.5
    80.              3.500.       9.1
    40.              7.001.       5.2
    40.              7.070.       5.2
    30.              10.100.     2.2
    30.              10.150.     2.2
    20.              14.001.     4.9
    20.              14.070.     4.9
    17.              18.068.     2.7
    17.              18.168.     2.6
    21.              21.001.     1.6
    21.              21.070.     1.5
Results from W1SFR EndFed:
         Band              Freq           SWR
    40.              7.001.        1.9
    40.              7.070.        2.5
    30.              10.100.     4.4
    30.              10.150.     4.5
    20.              14.001.     4.5
    20.              14.070.     4.3
    17.              18.068.     1.5
    17.              18.168.     1.5
    21.              21.001.     1.8
    21.              21.070.     1.8


  1. Hello Mike, I think a multiband endfed like this is always a big compromise. It will tune (with tuner) and it will work. Actually I don't see much difference with/without counterpoise. I think that is right, a counterpoise is just to prevent the coax from radiating. I hope the antenne does a good job for you. 73, Bas

    1. Good evening Bas very nice to hear from you, yes I was hoping I would see a change for the better with the counterpoise but the SWR seemed to be better or the same in most places on the bands. I stuck with no counterpoise for the time being but it's very easy to hookup if I wanted to. I have noticed with this antenna I am not having any RFI issues I had with the other antenna. I am able to go above 30 watts on 40 without issue. I am all the way up to 60 and no problems.
      73 and have a great upcoming weekend.