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[Articles Home]  [Add Article]  

DX Engineering RX 4-Square

Carsten Esch (DL6LAU) on February 10, 2006
View comments about this article!

First: We (DL4LAM - Peter, DL6LAU - Carsten, SM6CNN - Anders, SM6CMU - Ingemar, SM6DOI - Staffan,) are not connected to DX-Engineering in anyway - in fact it was the first time I 'went shopping' at DXE ... But: As both SM6DOI and me are selling amateur radio products here in Europe, we are always looking for products to distribute ;-) ...

As early adopters, DL4LAM and I were very interested in the RX 4-square from DXE. Somewhere (on the Internet?) there was the claim it will work like 240m long Beverages but will 'only' need a 41m x 41m footprint for optimum performance on 160m. Unfortunately there were not many 'real-life' reports found.

2 weeks ago DL4LAM and I placed the order for:

- DXE-RFS-1P Receive Four Square with Controller
- DXE-ARAV-4P Active Receive Antenna, vertical configuration, pack of 4
- DXE-RPA-1 (optional preamp)
- some small stuff like connectors and the like ...

Than the big question for me (living on a 30mx30m lot) was were to put them to try ... To make it short ... I decided to visit Staffan, SM6DOI close to Gothenburg. Staffan is well known for his 160m expertise, he has a 50m tall vertical to transmit (very close to the Baltic Sea -- Swedish West coast) and 8 Beverages for RX.

In detail these are:

0 180m long
60 180m long
120 240m long
180 200m long
240 240m long
300 200m long

All up 1,5 meters, 9:1 ferrite balun, terminated with 460 ohms, Ground rods are one meter at the terminated side and three metres at the feed point. All coax is RG58. Ground under the antennas is wet blue clay.

Uli, DJ2YA was kind enough to measure the exact velocity factor of the used RG-6 coax (0.84 in our case) so I could cut the delay lines as explained in the manual (you can download these from DXE if you need more details) and installed the so called 'Snap n Seal' connectors - btw - these connectors are great an so easy and quick to assemble, never saw them b4 in Europe ...

Thursday morning I loaded the car and drove about 700km to meet Staffan. He and SM6CMU had already prepared some wooden pallets (still a lot of snow on the frozen ground in SM) with a short aluminium tubing for the active vertical elements. They also had positioned the palettes that the side length of the 4-square was 135ft (41.15m) and that 2 of the elements were pointing to 310 (resulting in 40, 130, 220for the other directions).

A 1m ground rod was used at each vertical. When I took out the 102in (2.6m) 'long' whips Staffan and Ingemar were looking rather amazed. This should work like a 240m long Beverage - hard to believe ...

The RX4SQ was positioned about 100m from the shack and about 200m from the TX antenna. One of the Beverages was close to one element of the RX4SQ (within 3m or so) and an unused 10m tower was about 20m away. Other than that the 4SQ was on an open field ...

The installation went very quick. Back in the shack we had an ORION I and a box were the Beverages could be selected. The same box had another RX input and we connected the 4 position switch for the RX4SQ to this input. This allowed us to instantly switch between the 2 antenna systems for A - B comparison.

As it was still daylight we checked the performance on the OK beacon on 1854kHz. The result was amazing. The F/B of the RX4SQ was very good (25-30dB) with a very clear forward lobe. Ok, it was still daylight, probably it will only work nice at day ;-) ...

But when dawn came, we had the same results ... The signal output of the RX4SQ was lower than the Beverages but there was not a single case were the RX4SQ would have lost a QSO compared to the Beverages. We than tried the optional preamp from DXE and signals got stronger (with more or less the same SNR). It was more a personal taste ... I liked the 'stronger signal', some others from the test crew didn't ...

We only made a handful of contacts during the first day of the contest spending hour after hour comparing the Beverages against the RX4SQ. We compared the antennas quite some time on signals from NP4A, PY7ZY, 6O0N, VP9I, KG4SB, 9N7JO, PJ2T, HA7TM/HI9, HS0ZDJ, W's, JA's and the result was ALWAYS the same ... The difference was VERY SMALL in most cases, sometimes the Beverage was 'a little bit' better, sometimes the other way round. Very often there was really no difference.

The second contest night brought the same results. After sunrise we disassembled the RX4SQ and I took another 8 hour drive back home where I am just typing this as the contest will last another 3 hours ....

So talking about the comparison at the SM6DOI QTH, the RX4SQ worked like advertised and MUCH BETTER than we all thought. One might say that maybe Staffans Beverages do not work well but looking at his results on 160m I think they work (quite) good (on his very good ground). Maybe it was an advantage to have the RX4SQ on very good ground also ...

There would have many more tests possible but a long weekend is just too short ... We thought about reducing the side length in the second night to 70 feet and see how the system works with this spacing but this would have caused some more work in cutting the delay lines to the new length. 'Social commitments' did not make this happen - maybe next time ....

We did some listening on 80m and 40m too and 80m seemed to perform very well with the spacing we used too. On 40m the directivity was very low but the array was still very good on receive (always compared to the above mentioned Beverages)

For us, the performance was truly outstanding for 4 phased 2.6m long whips.

Hope that all the details did not bore you, we wanted to give you some more insight about the installation rather than saying

"THE DX Engineering RX 4-SQUARE WORKS GREAT" ... (although this would have said it all)

Well done Tom and DXE ... Maybe I will add some more thoughts later ...

We enjoyed listening to your signals (no VK, ZL, W6 heard here)! I will gladly answer questions about 'our installation' and the like if you have some ...

Regards,

Carsten, DL6LAU (and DL4LAM, SM6CNN, SM6CMU, SM6DOI)

Member Comments:
This article has expired. No more comments may be added.
 
DX Engineering RX 4-Square  
by W2WO on February 10, 2006 Mail this to a friend!
Very, very interesting. Thank you for a good report. If you can add more comments later, about using the RX 4-Square in a more dense population area that would be even better. I have always believed that 160 meters was a game for those who live in rural areas. If this antenna system is as good in a more populated area as it was in a rural area I need to rethink my plans!

Bill - W2WO
 
RE: DX Engineering RX 4-Square  
by NS6Y_ on February 10, 2006 Mail this to a friend!
There was a 4-square set up at the last get-together (AmTech Day) at SLAC, I dunno if it was DX-engineering or homebrew. Contacts were being made, at 500 watts, and I noticed the 4-square being switched a lot to change direction, it seemed to be working well.

The cops around here all have 4-squares on their cop cars for VHF lol!
 
RE: DX Engineering RX 4-Square  
by K0BG on February 10, 2006 Mail this to a friend!
I hope Tom, W8JI and John, WUN both see this article, and comment.

Alan, KBG
www.k0bg.com
 
RE: DX Engineering RX 4-Square  
by K6AER on February 10, 2006 Mail this to a friend!
Carlsten,

Very interesting article and thank you for sharing your test with us. When you had mentioned the receive signal level in the DX Engineering RX 4-Square was slightly lower then the beverage antenna, this is not important. Question of the week was what was the difference in carrier to noise ratio between the beverage and the DX engineering unit. Also when using the preamp did the C/N change. Was the test area for the set up in a quite region and did you have any nearby broadcast stations?

Many locations in the US the local broadcast stations are located close to town populations. Did DX Engineering give any specifications for the preamp units.
 
DX Engineering RX 4-Square  
by NC0B on February 11, 2006 Mail this to a friend!
I would be interested to hear feedback on the 4-Square in an urban environment. While I have not used this version, I tested the single horizontal dipole version for the 2006 Passport to Worldband Radio. The receive site was 10 miles NW of Boulder, Colorado, in the foothills, and the head amp was overloaded with MW stations from the Boulder, Longmont, Brighton area. There was IMD all over the HF bands. W8JI suggested I adjust the jumpters in the head amp to roll off the broadcast band. This makes the antenna really fall off below 3 MHz. The jumper change totally solved the IMD problem, but made the antenna rather dead on 160 meters.

K3LR sent me pictures of his DXE 4-Square installation, and he was very pleased with the results in rural PA. What would happen if one tried to use the 4-Square near Parker, CO, SW of Denver, with KOA at 50 kW a few miles away? Don't think it would work.

The dipole version has two whips, and an 18 foot wingspan. The only other active antenna I have ever tested for Passport that was worth using on a long term basis is the Wellbrook loop out of the UK. What would happen if one put four of these one meter diameter loops in a 4-Square? The problem here might be the directivity of the loop, which might be significant on 160 meters. Maybe Andy at Wellbrook will comment on this, as he has done some phasing tests with two loops.
 
RE: DX Engineering RX 4-Square  
by W8JI on February 11, 2006 Mail this to a friend!
Rob,

You cannot phase loops in a 4 square arrangement very well because phase response of the loop inverts 180 degrees as you pass over the null area. They are not "constant phase" with diffrent directions like a vertical.

N08D and a few others have tough IM environments, and not a lick of BC IMD on their units.

As I recall we had you set the jumper for 80 because you were comparing it to an 80M and higher frequency loop, rather than a 1.8 MHz setting. Or am I confusing you with someone else?

73 Tom
 
DX Engineering RX 4-Square  
by NQ4I on February 12, 2006 Mail this to a friend!
I too have evaluated the DXE 4 SQ at the nQ4I M-M contest stations. I made the 4 square available to the 160m station and both 80m stations. "The DXE 4 SQ is equal to or better than my 4@800 ft beverages. It has excellent f/b ratio and great directivity. All operators of the low band stations at NQ4I had very favorable comments. If space for long beverages is not available, then this system is the only way to go. My results are available from W8JI or DXE. I highly endorse the DXE Rcving 4 SQ. Thanks for an excellent product de Rick NQ4I.
 
RE: DX Engineering RX 4-Square  
by W1JIM on February 13, 2006 Mail this to a friend!
"The cops around here all have 4-squares on their cop cars for VHF lol!"

Sorry to disappoint you but those are for the LoJack trackers (which "my" company developed and built). Interesting thought though.
Jim Blumenfeld
W1JIM
 
DX Engineering RX 4-Square  
by WIRELESS on February 18, 2006 Mail this to a friend!
Does anyone on this site know the difference between the words "then" and "than"? When the FCC gets rid of the cw test they should add a spelling and grammar test. Current licensees would fail.

Old fart hams who are worried about the dumming down of ham radio should be worried about dumming down grade school and high school.
 
DX Engineering RX 4-Square  
by K8UR on February 21, 2006 Mail this to a friend!
Phased Arrays using small loops have been around many years and work very well. A "pencil" beam can be formed by a grouping of loops, and steered electronically.

Why more of these are not in use on the Ham bands is a mystery...

K8UR
k8ur@eHarbor99.com
 
RE: DX Engineering RX 4-Square  
by W4GCB on February 25, 2006 Mail this to a friend!
Dumming? Try dumbing ....
 
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