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[TowerTalk] GAP 8-Band Antenna as a DX Antenna

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Subject: [TowerTalk] GAP 8-Band Antenna as a DX Antenna
From: (Roderick M. Fitz-Randolph)
Date: Wed, 14 May 1997 20:30:43 -0500
I recently posted the following to the Reflector:

I have a friend (W5JUQ) who was long dormant and has recently revived
his activity.  He is severely limited in his antenna space but likes
to work DX.  He asked that I look at and give him
my evaluation of the Challenger DX 8-Band Multiband DX Antenna.

I defer to you that may have experience with this antenna, especially
in reference to his ability to work DX.  Please keep in mind his lack
of space.  I believe he would like an owner's appraisal.  Anyone out
there own one?  Do you like it and why?  Do you dislike it and why?

Thank you for any replies from those that have actual experience with
this antenna.

Rod, W5HVV

As a result of receiving a number of requests for Following is a summary
of the responses I received.  In the interest of brevity, I've omitted
the headers and signature information.
 His requirements is the exact reason we designed and build the ZR-3. The
 basic design criteria is:
        greater than 90% efficient
        can potentially fit below a fence line
        handle maximum legal power
        no traps
        no loding coils
        no radials

 The ZR-3 is a full size vertical dipole for 20-15-10 mtrs. It is in a
 compact arrangement that is only about 6' tall. This center portion is
 called the center radiator. The remaining length for all the three vertical
 dipoles is located in a ring on the top and another on the bottom. The rings
 are not closed, or they would be a capacity hat, which would not work for
 this design. The ZR-3 is better than 93% efficient, has no radials, no
 traps, no loading coils. It is designed to be mounted 2-3' above the ground.
 It can be higher, but since it is a vertical dipole, it should be kept so
 that the center is not higher than a 1/4 wavlength; otherwise, the vertical
 dipole begins to create a high angle lobe. The ZR-3 is an extra ordinary
 antenna and is less than 1dB down from a full size vertical dipole on all
 bands. This puts it ahead of the firld.

 The ZR-3 is a balanced antenna and is fed right at the center. It is
 possible to model it on a computer and has been done by several people. The
 original design was delevoped for a commercial customer. It performed to
 spec, outperformed all of their large wire arrays and they have since
 ordered many more.

 The low bands are also a challenge. We do have a 40 mtr model, as well as a
 40-30 two band. These are not ready to be released yet, so they are not
 advertised. The lowest frequency we have running commercially is 4.2MHz, so
 an 80/75 is not far away.

 You can see a photo and read more about it on our web page.

 Please take a look at it. You won't be disappointed. I have used one for
 more than a year, including mobile for about 2,000 miles. It is mechanically
 solid and easy to assmeble, as it comes almost fully assembled.
 For what it's worth, I use a Cushcraft R-7000 or R-7 here, to get me down
 to 40 meters.  The R-7000 is built like a battleship but the R-7 tweeks
 up better.  In any event, with the R-7000 only 8' above ground and a mere
 250 watts from a Drake L75, I have worked both VK0WH on Macquarie Island
 and VK0IR on Heard Island.  I had to revert to my generic tri-bander to
 work BS7H but I really don't think they were ever on 40 meters.

 The point of all this is that one of the compromise verticals will work
 OK but you gotta pump about 250 watts into it.  With just 100 watts, it
 is works as a great noise receiver and tests your patience more than

 I'd be leary of an 8-band antenna; 7-banders are bad enough.  In any
 event, don't let your friend try a G5RV.
  I have used a GAP VI for about 7 years with excellent success.  It
 performs to specification as essentially a vertical dipole (with slight
 variations on some bands, due to the different matching and coupling
 functions on each band by the rods).  Mechanical performance has been very
 good, with no signs of stress, cracking, or breakage.  I have my VI, which
 is about 32' tall, guyed with 3/16 nylon rope to control sway, with the
 guy point a few feet above the center insulator.

 I have used the antenna successfully on 6 and 2, with excellent coverage
 of distant repeaters compared to standard 2 meter verticals.

 The antenna, of course, will not compete with a standard Yagi on 20-10
 meters, but it has played well against the more stricted performance of a
 Butternit HF 5B on 20 (where the 5B is weakest).  On 40 and 80, the
 performance has been quite good, with clear low angle performance.  I do
 not have another low band antenna with which to compare the VI.

 The antenna your friend is comtemplating should performa similarly to the
 VI where the coverage of the two overlap.  In all cases, there are
 antennas for each band better than the GAP, but for an all-band affair
 that takes minimal ground space, the GAP has done a very good job for me.
 And, if your friend can later go to better individual antennas, the GAP
 makes a good back-up antenna for when the wire breaks or the rotor goes
 Hello Rod PLEASE PLEASE tell your friend to spend the money on an antenna
 that WORKS (I swear!) It is the Unihat CTSVR . The price is about the
 same. It is much better construction. Mine has taken  a lot from Mother
 Nature ! I do a lot of low band work. 160M and I get consistent S-10 to
 20 overs from the East coast to the mid west. Running 300Watts AM. When
 I am in SSB it naturally gets out a little further. This ANT WORKS, Rod.
 The E-mail address for Ed Goodman N5NUG is : or you
 can call landline : 214-352-4623. The Ant.has about a 3.5db gain on 40M
 This is truly a working unit. The Gap (I owned one till ice broke it in
 half) was a radiating dummy load that caused me some RFI complaints.
 From JUly 4, 1990 till August, 1993 when I put up a 55 foot tower with a
 Mosely Pro-67B antenna, I used a GAP vertical. It was a DX 6 as the 8 band
 model wasn't invented yet. I was mounted at ground level (I used a couple of
 radio shack chimney antenna mounts to secure it to one of the posts that
 support the sun roof on my patio). I laid the 3 radials on the ground in
 zig-zags and L shapses. To tell the truth, it worked just as well without
 the radials.

 I loved it. Granted, there were a few more sunspots then (but there will be
 more in a year or two), but I worked 248 countries with the GAP and 100 watts.

 It was virtually worthless on 80 meters, but worked very well on 40, 20, 15,
 12, and 10 meters. I also used it on 30 m and 17 m with the internal tuner
 in my ICOM 765... it easily loaded to a 1:1 swr on those bands. I understand
 the new one covers those bands. My GAP covered all of the bands (except 80
 where the 2:1 bandwidth was 120 KHz) with an swr of less than 1.5:1. It was
 nice being able to just switch bands on the ICOM and start transmitting.

 Will it compete with my Pro67B at 65 feet, especially since I've added a
 1500 watt linear? No way. But it worked very well for me. My wife liked it,
 because it has a very clean, unobtrusive look to it. I think it's an ideal
 antenna for the "space challenged" ham.

 My opinion... but I was very sorry to see it go.
 I have a Gap Challenger in my back Yard you know the 45 ft tall
 version. It works well on 40 and 80. It's marginal on 160 and a dummy
 load on 20 mtrs.
      All conventional HF verticals are all based on a 1/4 design, generally
 trapped for most of the bands.  They all need a ground radial system (forget
 what the manufacturer says), are relatively ineffficent and have limited

     The new Force 12 AR-3 that covers 10, 15 and 20M blows all of the
 aforementioned antennas out of the water.  It's 3 full-sized vertical dipoles
 so it's over 95% efficient, has great bandwidth and really DOESN'T need
 ground radials. If I was in the market for a limited space vertical antenna,
 I'd buy one in a New York second.  They're $449.00.
 Rod, I trucked one of these puppies all the way to Dubai.  On 20 and 40 it was
 very good for a vertical.  On 80 it was worse than a simple dipole.  It was
 actually deaf...although I was told in North America my sigs were louder on it
 than the dipole...even though on receive it was down 2 S UNITS off the dipole.
 On 160...forget it...worst dummy load I ever used...don't buy this thing
 if your buddy has ANY THOUGHTS of low band activity.  I have used a butternut
 with better results.

 Here I bought a hytower...NOW THAT's a low band vertical...and it is much
 shorter.....also the hytower tunes on every band 10,12,15,17,20,30,40, 80 and
 160 with the wire extension (inverted L, basically).

 Rod, look at the Uni-Hat CTSVR, it tested 18.5 dB better than the
 Challanger DX by GAP. Give me your mailing address and I will forward
 info. 73's Ed - N5NUG


                       (Proprietary Design Patent Pending)

 Multi-Band Operation (160-80-40 and 17 Meters)
 Compact 31 ft.  1 in.  Tall
 Top Loaded ...  No Traps
 Automatic Band Selection
 Heavy Duty Construction
 Stainless Steel Hardware
 Single 50 Ohm Feed Line

 The CTSVR requires an  area 25' by 25' in your lot or  yard to achieve
 160,   80, 40 and 17 meter operation.  The  ground system required is
 one 4' to 8'   ground rod  at the base  of the  antenna and a  minimum
 of six  radials 34'   long.  Excellent band width accomplished with
 proprietary easily tuned feed system.   Tuning of  operating frequency
 is easily  accomplished from  the   ground  for  all bands  of
 operation  by  trimming two tuning  stubs  and   positioning of a tuning
 slug in the insulator assembly.

 Inverted radiation pattern with the  maximum current point 30' above
 ground   level.   This produces  a highly   efficient  low  loss
 radiator  in  a  short  structure twenty two  degrees   electrical
 length on 160 Meters. Lower noise  figure as  compared to  other
 vertical  designs due  to unique elevated feed system, loop construction
 and efficient top loading design.

 Performance and Specifications Data:

 Power Rating: .......................... 1.5 KW-CW
               .......................... 2.5 KW-SSB
 Band Width (2:1): ...................... 160M-47 Khz ... 80M-87 Khz
                   ...................... 40M-250 Khz ...17M-500 Khz
 Feed Point Impedance: .................. 50 Ohm (+/-5)
 SWR: ................................... 1.5:1
 Recommended Feed Line: ................. RG213/U
 Ground Rod: ............................ 4' Minimum
 Number of Radials: ..................... 6 (Optional)
 Radial Length: ......................... 34'
 Height: ................................ 31' 1"
 Mast: .................................. Telescoping
 Top Hat: ............................... 17' Dia. Aluminum w/ # 14
 Copperweld Wire
 Foot Print w/4 Guy System: ............. 25' x 25' Area (Optional)
 Wind Surface Area: ..................... Approx. 9 Sq. Ft Total
 Est.  Shipping Weight: ................. 47 lbs.
 Suggested Retail Price: ................ $499.00 (Shipping Extra)
           Uni-Hat CTSVR
 160, 80, 40 & 17 Meter Vertical
           3816 Royal Ln
         Dallas, TX 75229
 See the extensive review of the GAP verticals by K5FUV
 in January 1995 QST at the end of the product reviews.
 There is no mention of it in the table of contents.
 I don't remember which page.
 Rod, I recently asked someone about the Gap vs CTSVR Unihat antenna, he had
 tried the GAP first and says the ctsvr runs circles around the GAP.  Not
 sure who I was emailing because all I had was the email adr and it didn't
 include a call sign.  The name is fred cresce <
 He was especially pleased with the 160m operation of the ant.
 Check with K4RO/NI4M/N4ZZ as they have *HAD* GAP products ... key
 word is HAD ... Mike WA4CBF uses one, but he lives NEXT DOOR to WLAC
 1510 AM Radio and "benefits" from their ground plane ... ANYTHING
 plays well there at his QTH !!!

 I'd suggest looking closely at the CC R-7000 series while at Dayton ...
 I have the large one (Titan or Voyager) that only covers 20, 40, 80
 and 160.  However, the design principles are similar.

 It's pretty good on the higher bands, but on 160 it is totally
 useless (10 dB below a full size vertical).  I guess the smaller
 model will suffer from the same malady, but at a higher frequency.
 Looking at the scale, it should play relatively well down to 7 MHz or
 The Challanger (and ALL GAP models) use a fixed silver mica capacitor
 attached to the RG-8X coax feed inside the antenna to obtain resonance on the
 lowest frequency. So it is useless on 80m as an example. The three radials
 recommended are a joke.

 I strongly urge your friend, IF he wants WARC bands, to get a Hy-Gain DX-88,
 or Cushcraft AP-8A and install, fold, bend, etc., as many radials as
 Cut grass 1-2 notches shorter than normal, raise mower deck.
 Buy 5-6 pkgs. of vinyl coated bobbie pins at drugstore. Pull handfull off and
 use each 3-5 ft. to pin raidial until grass thatch covers it in 3 mos. Now is
 a good time. By Sept his XYL will not see radials!
 Now IF he does not want/need WARC bands, buy an old faithful Hustler 5B-TV
 10-80m vertical and add radials. He will save a lot of money, which he can
 place in radial wire. #22-20awg is fine. Max length =60 ft. for 80m, but many
 30 footers will work!
 I just purchased a Gap Challenger but it is not up yet.
 I am really impressed by the quailty of the material.
 I looked at the MFJ 2 thru 80 antenna and after looking
 at the poor quality, I went with the GAP.  We needed
 soemthing for a small lot and did not want to have wires
 going everywhere.  We (my wife is also a ham - just passed her Extra
 written) figured that the neighbors would be 'nicer' if we tried to
 make the antennas as low impact as possible.  The GAP only requires
 3 ground radials - I plan to use some old coax (this is suggested by
 I have a GAP Voyager (160-80-40-20) and have exchanged and noted opinions on
 GAPs.  My Voyager works quite well on bands except the lowest (160) and I hear
 the same is true for the Challenger (in this case, 80).   Contrary to factory
 instructions, I have raised the counterpoise a few feet above the ground and
 installed a ground system and believe that improved my 80 meter results.
 Hi there...I have not used this antenna, but my friend, K7FQ does.
 He can be reached at:

 Hope he can give you the data that you need.
     I've been chasing DX with the GAP Challenger for a little over three
years with very good results.  I offer the following and ask that you keep
in mind the variables of location and operator experience.
     I've found this antenna to be well-suited for DX, especially when one
considers the lack of propagation on the higher bands. Totals worked
to-date: (CW at 1000W output and SSB at 1200W output)

               Total DXCC Countries         255
               Total CQ Zones                   36    (Need 22, 23, 26 and 24)
               CW                                   217
               SSB                                 168
               10 Meters                           50    (No propagation)
               12 Meters                             0    (No
               15 Meters                          145
               20 Meters                          191
               40 Meters                          185
               80 Meters                            35   (No interest)

     My QTH is 38 miles due north of Atlanta, GA.  The antenna is ground-
mounted in a heavily wooded area.  The soil is a mixture of rock and red
clay.  I'm feeding it with 120' of 9913.

     I assembled the antenna to the specifications provided by the factory.
Total time was about 2 hours.  Have full bandwidth on all bands below 2:1
except for 80M where the bandwidth is 100khz.  This was a really easy
and painless installation.

     The antenna is painted with tri-color camo paint to make it less
noticeable (invisible?).  Painting is no problem if required.  I don't
have any guy lines on the antenna and it still standing straight.  I
have heard of some cases of structural failure in the lower section
but that has not been the case here.

     When ordering the antenna one must make a choice between 75
and 80 meters.  Not enough bandwidth for both.  The factory supplies
the correct top-load capacitor based on the operators choice of center
frequency.  Expected bandwidth is about 100Khz.

     This is the best vertical on 40 meters I've ever used.  Made Heard
and Peter I. easy catches.  There is no doubt in my mind that it
out-performs the HF2V I had in NJ with 100 radials under it.  Amazing.

     With an assist from the packet spots I worked DXCC in 15 hours in
the '96 CQWW CW.  Even without the packet spots I've worked 108
countries SSB and 109 on CW in the 1994 CQWW 'tests.

     I have no doubt this is a 300-Country antenna at this location.
    (I have 315  from the old QTH.  It's been a hoot starting over).

     I've done both 5BDXCC and 5BWAZ and never owned a tower.  The
secret to enjoying chasing DX on this, or any, vertical is going to be
directly proportional to the amount of time spent on CW.  If the goal
is mostly or strictly SSB it's going to be a bit tougher.

     With the exception of being a little hard-of-hearing on 80M I think
this is a fine DX antenna for limited space or restricted conditions
operation.  I'll be happy to answer any questions your friend may have.

Hope this may have been of some interest to those of you that, like my
friend Terry (W5JUQ) has an interest in antennas for a minimum space

73, Rod  W5HVV

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