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Reviews Categories | Antenna Switching, Phasing, Controllers | Comtek 4-Square Systems Help


Reviews Summary for Comtek 4-Square Systems
Comtek  4-Square Systems Reviews: 16 Average rating: 5.0/5 MSRP: $319.95-349.95
Description: Comtek has manufactured the ACB-4 series of 4-Square Phasing Systems since 1990. Incorporating many improvements since 1994, the ACB-4 "Collins" series produces up to 5 dB gain and 20-25 dB Front to Back in a properly constructed 4-Square array. Available from 10 meters to 160 meters in single band models. More information available at www.comteksystems.com
Product is in production.
More info: http://www.dxengineering.com/search/brand/comtek
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VE9AA Rating: 5/5 Oct 23, 2016 09:00 Send this review to a friend
Quiet ! Slight gain, FB F/B !  Time owned: 0 to 3 months


A couple folks asked me where I was getting my gain and F/B #'s from.

Fair question.

First of all, I have no doubt the S-meter on an IC-7410 is not accurate, but
everything is relative.

I just performed these measurements moments ago using my AA-230PRO as a
signal source about 200' Southwest of all 3 arrays and also equidistant to
the ref antenna which is an HF9V which also has raised radials. On 20 & 40
this is probably a pretty fair ref. antenna. On 80m, not so much.



I'll express them in S-units, and someone wiser than I can extrapolate to
dB/S-unit if they happen to know it as fact for this radio.



First, all 3-arrays have metallic clutter (or each other), or an 160m
inverted L very much in the near field.). A couple delta loops for 15m & 20m
are also close by.



All readings taken with a SW source/signal generator ~ 200' away.(my
AA-230pro)



>From my understanding an S-unit on a modern Icom is somewhere between 3 -
6dB ?....is it linear from S1-S9 (doubt it)



20m

HF9V - S7



Array - SW - S8

SE - S2

NE - S1-2 (varies a little with the wind.call it S1.5)

NW - S3

Gain over ref 3-6dB? F/B 18-36dB?



40m

HF9V - S5

Array - SW -S6

SE - S2

NE - S2

NW - S3

Gain over ref 3-6dB? F/B 12-24dB? Low due to being nested inside NW
quadrant of 80m array?





80m

HF9V - S5 (unfair reference)

Array - SW - S8

SE - S3

NE - S0 (could hear signal, can't measure it)

NW - S6 however this array aimed NW is aiming at all other antennas and a garden
shed, cars, etc. so maybe I should not be surprised)



Gain over crappy vertical 9-18dB? (real gain 3dB?) F/B Excellent @ 24-48dB







So, it's obvious it all doesn't work perfectly, and F/S seems to suffer a
little here and there, but compared to the reference antenna, they have some
gain and F/B is pretty good. F/S is fair.



I don't know if at only 200' away this is a fair or accurate test.



Mike VE9AA

Mike, Coreen & Corey

Keswick Ridge, NB



From: Mike Smith VE9AA [mailto:ve9aa@nbnet.nb.ca]
Sent: October 14, 2016 11:22 AM
To: 'towertalk@contesting.com'
Subject: Wire 4-squares - they work ! (long)



de Mike VE9AA (long)



I've received a few direct emails and also some questions on some of the
smaller reflectors and chat pages I belong to, so though I would just post
my *experience* with these here for you to collectively ruminate.

Keep in mind, I have done very little with them yet. Some DXing, a 1 hr
CWT(contest-sorta thing) and some listening. I am an EE Technologist, not an
E Engineer and I couldn't run NEC-4 or any other antenna modeling program to
save my life. I am just a regular guy who loves contests and does a little
casual DXing, and am relating my experiences and not trying to convince
anyone I did anything better than what more knowledgeable Engineers or real
station builders would do. Thus, take all this with a grain of EE salt.



A few days ago I installed my 2nd 4-square; one for 40m. Already have a
small one for 20m(tnx Bob!). As fun as it is to use I am nearly sure a 3-el
yagi at 48' would woop the 20m ones' butt.(but I have no towers and it is
quiet) I am sure the 40m one will be a couple S-units down from even a
2-element shorty-fourty up high, but it's QUIET. Direction switching is
nearly instantaneous. In the CWT with a disturbed Ionosphere, I found that
beaming SE (towards ZS6) I was able to work some of the big W1's/W3's on
what sounded to me like backscatter. I've never owned a beam on 40m, so I
can't say for sure. Beaming SW(true bearing) their signals went way down.



Two nights ago I finally got my 3rd (wire) 4-square working..80m 4-square -I
really never expected much based on the 20m & 40m ones,(20m one is "meh"
(but quiet) and the 40m one is pretty OK, but feel it could be a bit better,
gain wise.



The 80m one though.WOW---I just had to share this.. I was already working
EU's about 50mins before my SS (Sunset). (big stn OK1AWZ w/a 3-el beam
followed by a string of other stns).....a couple hours later I worked VU2GSM
@ his SR (sunrise) Kanti is running medium power and a dipole in a noisy
environment. I never heard him work any other NA or even heard any other NA
callers the few times that I tuned by. I was running around 600-700w on 80m
cw. (the next night I worked Kanti on 40m and still never heard any other NA
callers|). Maybe everyone has already worked him on 40 & 80m..don't know- I
don't do much Dxing..just now and then, so perhaps he's quite popular)



I am sold. Wires in trees that ACTUALLY work ! Call me a believer.



I am already resigned to the fact I'll have ongoing maintenance issues with
it, as its 100% made of wire & rope, in the woods supported by trees that
sway and has 2 raised radials* each, some of which the deer *will* get
caught up in. ( I already know this from previous antennas) The verticals
are black #14AWG stranded/insulated R90(?) and the raised radials are
*galvanized steel fencing wire(partially because some are low and deer will
fight with them and partially because copper is bloody expensive here). For
the radials I carefully made a hz dipole and tweaked them to resonance at 5'
above ground. For the first vertical I installed the whole antenna, but my
calculations were bang on and I did not need to tweak it. Just made 3 more
and I was in business. I also measured my RG6-type feed lines as 82.5% vf
as opposed to the advertised 84% vf. Cut so X=0 at the bottom of each band
if my memory serves.(AA-230pro)



In this tiny stand of sloping woods that is <0.2acres I have some standing
dead trees and some "widow makers", and lots of deer that pass through it
literally daily, so things will become damaged over time, I am 100% sure.
Everything is contained within the "box" or "square". As viewed from above,
there are no wires extending outside of the box and no wires going towards
the center controller (except coax of course). Two raised radials per
vertical. (would 4 or 8 work better? Yes, most likely..but I was out of
space!)

On each side of the square, 2 radials (one for each vertical) pass close to
one another (about 1 foot). I found my 20m array that's NOT in the woods,
and is contructed is quite similar but uses aluminum verticals is very
twitchy when it comes to radials passing close to one another so I tried to
be creative in getting some good spacing on the 40 & 80m ones. Did it help?
Don't know.



What I find is that they are so quiet as to almost not be believed. I live
out in the country on a Ridgetop @ 660'ASL and except for a nagging electric
fence to my NE I have always thought I had a quiet QTH. Even the 40m one is
eeerily quiet. I heard VP9/AA1AC last night at s5 on the HF9V(lots of
raised radials) but the atmospheric QRN was bad. Switched to the 4-Sq and
he was maybe only S6+, but hardly any noise. First call,(@100w only) and he
was in the log. (a pileup of on top of him too....maybe that was unfair as I
am relatively close and I am sure most of the pileup was either EU or from
out west W6/W7).The 20m one does not work quite that well however it is also
vy quiet. As I said, a normal tribander would likely beat it on 20m.<<
comments?



Took me around 2-3 weeks to get all the wires up in the trees(fishing rod &
golf ball method-not easy on rocky/mossy sloped ground with trees every
10-15 feet, but doable), phasing lines built and control lines run. All
vert's and raised radials are suspended by ropes. The bases vary from 3.5'
off the ground to about 8' off the ground, as the patch of woods they are in
is sloping (nw-se) very badly and I was attempting to keep them as level as
possible. The pain in the wallet was moderate for the Comtek contollers
once I paid for them, then paid exchange, taxes, duty and shipping , , but
probably cheaper than separate 40m and 80m yagis on a tall towers ;-)



I do not employ any coils and/or caps on the wires or ferrites (K1TTT) on
the RG6 feedlines. Before anyone tells me 120 gnd radials per vertical is
much better ; I will not ever be putting down any ground radials in this
patch of woods. It's on a steep slope with lots of rock underfoot as it's
on the edge of old farm land and 50+ yrs ago they cleared the field I live
on and rolled or tossed all the rocks "down over the bank" so walking is
precarious at best, with leaves and moss on top of rocks. Can't do gnd
radials here. The most I could probably do with these is to add 1
additional radial pointed towards and passing by, the Comtek controller. I
don't see a need at this point.



My stand of woods is really too small and I had to compromise on the 80m
spacing (way too close @ 62.5') but it seems to work anyways. Also, all my
80m ones are "inverted L's" as most of my trees are too short.(35-45' for
the most part) AC0C says they just "want to work" and Jeff is right. I
agree wholeheartedly. N8UM has been using 4-squares on most all bands and
swears by them. He is wise.



I am so excited about this type of antenna that I just had to share. Can't
remember the last time an HF antenna worked so well for me. Perhaps in the
early 90's when I actually owned a tower and had a TH6DXX that really kicked
it? There are no towers here at all and no plans for any. Would a 2-el 40m
shorty forty @ 100' work better? Probably. Would a 80m rotating dipole @
150' work better? Probably. Can I afford that? Nope. (hi)



I should mention, too, that the 40m 4-square is partially nested inside the
NW quadrant of the 80m one. I don't notice too much in the way of
degradation of F/B on either, but have not made too much in the way of
measurements with locals yet..with QSB, hard and fast measurement are
difficult to quantify.



If you have a chance and have trees in your back yard, I recommend them at
least on 40 & 80 ! (I still haven't heard from a single soul, nor found an
example on the internet of anyone who's compared a 4-square on 10, 15 or 20m
with a normal tribander @ 48'....I am curious about K3LR's claim.)



I'd like to hear more about YOUR 4-sq arrays and what has worked for
you.



Next up is a 2el PVS-2 for 160m..maybe for CQWW



Mike VE9 Antenna Antenna
 
N4YDU Rating: 5/5 Mar 17, 2013 09:32 Send this review to a friend
Excellent  Time owned: 0 to 3 months
Over the years I've often considered purchasing a Comtek 4 Square Box for 40M. This past January (2013) I took the plunge and purchased the box. Within two weeks I had it up and running using 4 aluminum verticals made from scrap collected over the years. I continue to be very happy with the results. The front to back is a little over 20 DB on average and the front to side is about the same on distant signals.

Most of my operating is during contests and it is a real joy to have the instant switching of direction. The forward gain is decent and slightly better (3DB) than my dipole at 70 feet when aimed in the same direction as the dipole. The signal to noise ratio on receive is superior to my other wire antennas on 40. I still have the wire antennas up because they out perform the 4 square in terms of gain on local contacts (about 400 miles or less).

I was so pleased with the performance of the 40M unit I went ahead and purchased one for 20M. I'm getting good results with it as well.

The verticals are ground mounted with 1/8 wave radials. I do not have a ton of radials on the ground. The 40M model has 24 per vertical and 20M version has just 16 per vertical. I do plan on adding more in the future.

If you have a good spot to place a 4 Square and are considering the Comtek Box offered at DXEngineering, I strongly suggest going for it. You will be happy with the performance.

73, Nate/N4YDU
 
OH5JJL Rating: 5/5 Aug 4, 2008 23:59 Send this review to a friend
Works as advertised  Time owned: 6 to 12 months
I have ACB-4 for 20M with ground mounted verticals. It's an awesome product! F/B with DX signals is outstanding 20 dB and F/S is also very good. I like the most quick heading switch - you don't need a rotator to change the direction in just a second. You don't need to climb either.

I have about 50 ground radials per element. I also tested elevated verticals with 4 radials. The gain was about the same but F/B wasn't so good. I suppose the balance between elements wasn't good enough so I'm back with monopoles. I have current chokes in every feedline just for sure.

Installing the radial field is a hard job (thanks to my XYL for understanding) but it's worth it. 4-square arrays are made for homebrewers. You need to build properly adjusted feedlines, radials etc. If you want an "easy" way, put a beam up to a tower.

Jim Miller is a very helpful person and his customer service is good.

By the way, my array is in the middle of tall trees. I haven't had any trouble with them. Maybe the array would work better in a field but I don't want to cut down those trees. I have heard good experiences from other hams with similar installation - don't worry too much the trees.

73 Tuomas OH5JJL
 
W9PL Rating: 5/5 Jun 15, 2008 18:54 Send this review to a friend
GREAT Results!  Time owned: more than 12 months
I renewed my acquaintance with Jim K4SQR in 1996, after having heard and worked him (almost 30 years ago now) when he was KZ5JM in the Canal Zone. Before buying my Comtek Systems ACB-4’s, I asked Jim for advice about my planned approach to use elevated radials and low-cost Hy-Gain 18V-S verticals. Jim has always been very eager to help with any questions I’ve had. I installed my Comtek ACB-40 40m and ACB-20 20m 4-squares in August 1996. I also bought the Comtek RG-11/U coax feeder cables. My array elements and radials are elevated (3 radials per element, sloping down from the feedpoint at about 8 feet above ground to typically roughly 1 foot above ground).

My 20m 4-square elements are “stock” Hy-Gain 18V-S verticals (without the base loading coil), about 16 feet tall from the feedpoint to the top. The average length of each radial is only about 13 feet. My configuration with “short” radials provides resonance and low VSWR due to proximity of the lower end of each radial to ground. At the feedpoint of each element, I use a RadioWorks 1:1 balun. The radials are very close to equal-length. The radial lengths were initially adjusted for low VSWR per element and re-adjusted slightly to reduce the “dumped” power, which is 1-3% of the power feeding the array (from 14.0-14.35 MHz).

My 40m 4-square elements are “modified” Hy-Gain 18V-S verticals (without the base loading coil), to which I added a single slightly-sloping wire at the top (about 5 feet long). The modification also involved replacing the upper 2 sections of the 18-V with compatible double-wall sections of aluminum tubing to lengthen each vertical from the “stock” height to about 23 feet and to provide additional strength. The total length (aluminum + wire) of each 40m element is about 28 feet. The average length of each radial is only about 20.5 feet. I used a similar approach for tuning the radials (as for the ACB-20), and the “dumped” power is 1-3% of the power feeding the array (from 7.0-7.2 MHz). Based on my experience, elevated radials much shorter than quarter-wave long work very well (for a configuration like mine).

My results for both 4-square arrays are as good or better than expected, with apparent “gain” of 2-7 dB compared to my “reference” R7 half-wave vertical. The “gain”, F/B and F/S obtained for the arrays depend on propagation conditions, time-of-day and distant station location. The F/B and F/S range from 10-30 dB.

I’ve really enjoyed the ease and thrill of working 20m and 40m DX using my ACB-4’s. Being able to quickly switch antenna patterns during a contest offers a real advantage. I strongly recommend the ACB-4 system, based on my experience and results.

Vy 73 de Paul W9PL
 
W8NSI Rating: 5/5 Mar 23, 2008 14:02 Send this review to a friend
The ACB-20 is great  Time owned: more than 12 months
My previous 20 meter antenna was a 1/4 wave ground plane. It was great for dx but you could not null out or eliminate interference (omni-directional).

I bought my Comtek Systems ACB-20 after I read the QST article titled "Rose Garden Array", 3 or more years ago. The article said it performed to near rotary beam specs. While I would not give it that, it has been a totally reliable antenna that works the dx because of its low angle of radiation. Each lobe is wide and overlaps each way so a rotatable array is not missed. Great front to back.

My only problem, in several years since I installed it: diodes in the control box got zapped last summer. Probably from a near lightning strike. They were easily replaced after consulting with Comtek. Turns out that a number of different diodes can be used.

If you want a good directional antenna but cant put up a tower, a 4 Square may be what you are looking for.

I use mine mostly on 14.070 - psk31. I love my 4 Square!

73 de jim w8nsi
 
K3LR Rating: 5/5 Mar 10, 2007 08:58 Send this review to a friend
Comtek is OUTSTANDING!  Time owned: more than 12 months
I have been using Comtek products from Jim, K4SQR for over 15 years. In that time Jim's attention to quality and customer service has continued to impress me. I have phased 4 squares for 80 meters (two ACB-4s with 8 full size self supporting verticals). They work outstanding. No problems, lots of gain, great front to back and low dump power. Look at how the K3LR 80 meter scores stack up against the East coast (K3LR is on the OH/PA border) and you will see that the Comtek 4 square is the secret to a super signal. There are lots of Comtek 4 square pictures on the K3LR web site. http://www.k3lr.com I also have Comtek 4 squares for 20 and 10 meters and have the ACB-4's in hand to add 40 and 15 meters this summer! I am also using the Comtek 3 HIGH stacking boxes and Comtek W0IYH chokes too! Every product has worked 100% perfect. You cannot go wrong with Jim and Comtek Systems!

73!
Tim K3LR
http://www.k3lr.com
 
K1TL Rating: 5/5 Dec 1, 2005 09:30 Send this review to a friend
Just utterly FANTASTIC!!  Time owned: more than 12 months
I have had the 30m Comtek 4square array now for just over a year. It sure beats my 30m loop. At first I just installed two vertical elements with about ten raised radials. It worked good but needed to add the other two directions.

After staking out the array, which took several days due to the "Rhode Island Nuggetts" we have in the ground and a stone wall, finally found three spots with no rocks and had to bore holes into a huge rock just below the surface of the fourth one to anchor the vertical. The most involved part of installing the array was the radial system. It is a pain but is worth it in the long run. I installed about 70 radials per vertical and used #14 for the radials and #10 for the buss system. I did this in October/November and just three days after completing all the soldering, etc, we had our first snowfall...just made it. It is amazing to hear the JA's coming thru long path where I could just barely hear them with the 30m delta loop.

I installed the dummy load in the shack to monitor "dumped power" which in my case, is about 2% of the output power. There are several large cedar trees nearby but do not seem to affect the system at all. Since I wanted to work into SE Asia, my system is oriented N/S/E/W and not the normally NE/SW, etc direction. Working VK9XG and VK9CG really made my day. Altho we in New England (Black Hole of Ham Radio) have a more difficult time getting into SE Asia, this array seems to work excellent when conditions are working for us.

I would highly recommend purchasing this system if one is thinking about installing a 4sq array.
 
VE2TKH Rating: 5/5 Jul 28, 2005 21:08 Send this review to a friend
Simply the Best!!  Time owned: 0 to 3 months
Hello,

I operated 12 days (week #1 and #3) on St.Paul Island CY9SS DXpedition with these excellent antennas on 40M and on 80M. Thanks to my friend Krassy K1LZ who brought them on the island... We worked as far as Oceania and Asia with them from St.Paul which is located in the Cabot Strait between Cape Breton Island and Newfoudland. In case you wonder where it is...

I can tell you that this antenna system simply "Rocks". It do the job and it will do the job again and again. When you go on a band with that antenna system, you can use the well known sentence "Let's Roll". It will give you amazing performance and service. Also, you only need to follow the instructions given by Comtek and it is easy as 1-2-3 to assemble.

Great performance, great product with high reliability! I definitely recommend that product from Comtek to every ham who wants to try it with no fear or doubt.

73
 
KY6R Rating: 5/5 Feb 21, 2005 06:00 Send this review to a friend
Excellent - 20M  Time owned: 0 to 3 months
I have a 20M 4 square with 8 raised and tuned radials per vertical. The Comtek 4 square system does exactly what I had hoped / expected it would do. Excellent F/B and S/N. The directionality is right on, and I have tuned my verticals so that there is zero power dumped in the phone band, and less than a watt in the CW band.
 
NI1N Rating: 5/5 Jan 10, 2005 10:34 Send this review to a friend
Fine antenna  Time owned: more than 12 months
This is an update and addition to my review from a year ago. In my previous review, I was using a 4 square for 20 meters. Since then, I built a new 4 square for 40 meters, also with 480 4/10-wave radials. This antenna performed very nicely, and since I have also been able to compare it with a 40 meter yagi.

The yagi is an OptiBeam OB2-40 mounted at 92 feet (28m). On the short path (mostly to Europe or Africa), the difference is hard to discern. On the long path (mostly to Asia), the OB2-40 wins by a landslide. But, the 4 square has better bandwidth and the instant direction changing is very nice (especially when hunting multipliers in a contest).

I've been so impressed by these systems that I also built one for 80 meters. I would only have room for 3 verticals unless I wanted to do some major tree removal (the top of the vertical would be in the branches), so for now I'm using the 4 square controller to control 2 full-size 80 meter verticals. This antenna has 240 4/10-wave radials (again, 120 under each vertical).

Wow! It is so nice to have gain and front-to-back on 80 meters! I haven't done many comparison tests with it, but I know it works well when there is a weak DX station and only a handful of people in the USA seem to be able to hear them and I'm one of them :) I don't recall having to wait in a pileup on 80m since this antenna went up, and on an average night one CQ has me working EU stations at contest-like rates until the band closes. During the CQ WW contest, this array played very well even when competing with the big boys in chaotic pileups.
 
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