I know there are hundreds of web links for building a good homebrew quad, I just thought it might be more productive to ask on here if anyone has built a good 2 Element Quad that performs nicely and resonates on 27.555, looking for the exact dimensions, arms, boom, wire etc... a drawing or two would be a great help too...:blush:
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11m Cubical Quad Dimensions
- Thread starter IrishDX
- Start date
I can dig up pics of a 2 el quad I built for 27 MHz a few years ago. I didn't record the dimensions of the spreaders, but used 1005/f for the driven element and added 5% for the reflector (bare wire) and just adjusted the spreaders a bit until the loops were even and under tension. At 5ft spacing it was a good match to a 1/4 section of 75 ohm coax and was pretty broadbanded. It worked well.
Incidentally, I compared it to a 2 el Delta Loop I had built for 10m with a DE and director. Aside from the quad having a bit greater bandwidth I saw no difference in the two as far as gain and f/b. I did use a gamma match on the delta, which may or may not have effected the bandwidth.
Quads are fun to play with and have roughly the same gain as a 3 element yagi, but they are harder to handle physically even though they are lightweight. Get some help when you go to put the antenna up.
Rick
Incidentally, I compared it to a 2 el Delta Loop I had built for 10m with a DE and director. Aside from the quad having a bit greater bandwidth I saw no difference in the two as far as gain and f/b. I did use a gamma match on the delta, which may or may not have effected the bandwidth.
Quads are fun to play with and have roughly the same gain as a 3 element yagi, but they are harder to handle physically even though they are lightweight. Get some help when you go to put the antenna up.
Rick
Here is some info on the 2 element quad I built. Like Rick said, I didn't write down the exact lengths or the wire, nor the spacing, but they are readily available with online calculators.
I hope this is helpful.
For those of you who may want the info on the antennna, here it is:
1 1/4" fence top rail (boom and top mast section)
1 1/4" PVC (2 pieces for boom end sleeves holding spreader tees)
1" PVC ( 8 sections for spreaders)
1" x 48" wood dowel (inside spreaders for rigidity)
1" PVC 4-way cross (2 for spreader center joints)
3/4" PVC (8 sections for spreaders)
1" PVC couplers (8 for spreader joints)
1" x 3/4" PVC bushings (8 for spreader joints)
3/4" PVC caps (8 for spreader tips)
3/4" PVC tee (1 for driver wire/feedline terminal connection)
16" wire shelf supports (8 for spreader rigidity)
project box (1 for 75ohm match section to pl239 solder joint)
u-bolts (2 for boom connection to angles)
threaded eye bolts (2 for PVC cross spreader center joints)
myriad bolts, screws, and nuts
Steel shelf angle brackets (2 for mast to boom connection)
wood squares (2 for spreader rigidity)
14ga wire of sufficient length
PVC boom end sleeves were shaped to match profile of 1" PVC crosses joining center of spreaders. 1/4"hole was drilled through the center of PVC crosses, 1/4" x 3" eye bolts were reversed through the holes into the 1 1/4" PVC boom end sleeves and secured with 1/4" bolts across sleeves through the eye of eye bolts. Sleeves allow for both mounting and sliding spreaders in or out to tune.
28.755 --------- 1.7:1
28.305 --------- 1.2:1
27.855 --------- 1.2:1
27.405 --------- 1.2:1
26.965 --------- 1.1:1
26.515 --------- 1.0:1
26.065 --------- 1.5:1
25.615 --------- 4.0:1
25.165 --------- 4.0:1
Got it up to 35 feet at the boom.
As stated above the match was achieved by using a quarter wavelength 75ohm section at the feed point on the driven loop (available length to cut with online calculators). The antenna was still in need of tweaking with the length I cut for the 75 ohm 1/4^ section, so someone suggested the coax choke you see in the photo inline with the match section. The details of the choke are:
1.) 1 1/2" x 6" piece of PVC white schedule 40
2.) drill 2 holes in the side of the PVC on same side each about 3/4" from the center of the pipe's length (this is for zip ties to hold the coil)
3.) run the coax down the center of the 6" joint of PVC and back along the outside of the same. Make 5 wraps of the coax around the PVC between the 2 holes drilled earlier, zip tie them into place permanently, continue along the 6" joint with the coax running it out the other end to connect it to the 75ohm matching section.
You can see from the posted SWR readings how it matched.
I have no analyzer or such so my stuff is make it, get the SWR as good as I can, and run it for fun.
The antenna in the background of my avatar photo, and the one posted above, is/was another homebrew. It's a 5/8^ vertical that has done a great job for me. Comparative performances are only anecdotal. As for locally, I've talked on both up to 40 - 50 miles. Regarding DX, it has been about conditions. The 5/8^ was in the air before conditions opened up last year, but I've made some very good contacts for the sporadic conditions I had. The quad did real good. I talked to and received everywhere it was opened to me. I know it outperformed the 1/2^ A99 I had up before. The backdoor rejection on the Quad was about 2 "S" units from about 3 miles out locally, and skip being what it is, about the same it seemed, although I had no way of being sure what I experienced was anything other than fluctuating conditions. I thought it did well for a two element beam.
Additional info from a helpful source:
I hope this is helpful.
For those of you who may want the info on the antennna, here it is:
1 1/4" fence top rail (boom and top mast section)
1 1/4" PVC (2 pieces for boom end sleeves holding spreader tees)
1" PVC ( 8 sections for spreaders)
1" x 48" wood dowel (inside spreaders for rigidity)
1" PVC 4-way cross (2 for spreader center joints)
3/4" PVC (8 sections for spreaders)
1" PVC couplers (8 for spreader joints)
1" x 3/4" PVC bushings (8 for spreader joints)
3/4" PVC caps (8 for spreader tips)
3/4" PVC tee (1 for driver wire/feedline terminal connection)
16" wire shelf supports (8 for spreader rigidity)
project box (1 for 75ohm match section to pl239 solder joint)
u-bolts (2 for boom connection to angles)
threaded eye bolts (2 for PVC cross spreader center joints)
myriad bolts, screws, and nuts
Steel shelf angle brackets (2 for mast to boom connection)
wood squares (2 for spreader rigidity)
14ga wire of sufficient length
PVC boom end sleeves were shaped to match profile of 1" PVC crosses joining center of spreaders. 1/4"hole was drilled through the center of PVC crosses, 1/4" x 3" eye bolts were reversed through the holes into the 1 1/4" PVC boom end sleeves and secured with 1/4" bolts across sleeves through the eye of eye bolts. Sleeves allow for both mounting and sliding spreaders in or out to tune.
28.755 --------- 1.7:1
28.305 --------- 1.2:1
27.855 --------- 1.2:1
27.405 --------- 1.2:1
26.965 --------- 1.1:1
26.515 --------- 1.0:1
26.065 --------- 1.5:1
25.615 --------- 4.0:1
25.165 --------- 4.0:1
Got it up to 35 feet at the boom.
As stated above the match was achieved by using a quarter wavelength 75ohm section at the feed point on the driven loop (available length to cut with online calculators). The antenna was still in need of tweaking with the length I cut for the 75 ohm 1/4^ section, so someone suggested the coax choke you see in the photo inline with the match section. The details of the choke are:
1.) 1 1/2" x 6" piece of PVC white schedule 40
2.) drill 2 holes in the side of the PVC on same side each about 3/4" from the center of the pipe's length (this is for zip ties to hold the coil)
3.) run the coax down the center of the 6" joint of PVC and back along the outside of the same. Make 5 wraps of the coax around the PVC between the 2 holes drilled earlier, zip tie them into place permanently, continue along the 6" joint with the coax running it out the other end to connect it to the 75ohm matching section.
You can see from the posted SWR readings how it matched.
I have no analyzer or such so my stuff is make it, get the SWR as good as I can, and run it for fun.
The antenna in the background of my avatar photo, and the one posted above, is/was another homebrew. It's a 5/8^ vertical that has done a great job for me. Comparative performances are only anecdotal. As for locally, I've talked on both up to 40 - 50 miles. Regarding DX, it has been about conditions. The 5/8^ was in the air before conditions opened up last year, but I've made some very good contacts for the sporadic conditions I had. The quad did real good. I talked to and received everywhere it was opened to me. I know it outperformed the 1/2^ A99 I had up before. The backdoor rejection on the Quad was about 2 "S" units from about 3 miles out locally, and skip being what it is, about the same it seemed, although I had no way of being sure what I experienced was anything other than fluctuating conditions. I thought it did well for a two element beam.
Additional info from a helpful source:
73Simon004 said:
All great info, for detail and I repeat very detail on quads visit L.B. Cebik's site, he is "the authority" on quads and goes into great detail on size and spacing for gain and rejection.
I read somewhere that PVC and CPVC pipe has electrical conductivity properties.
the first quad I built, used PVC pipe and could not get it to match, when I switched to fiberglass, i was able to get it perfect.
here is a pic of my quad spider
please let me know what you think, I would like to offer these for sale but am unsure of the popularity of quads, whats the wind loading on that, wow, its looks very heavy duty
Rick
the first quad I built, used PVC pipe and could not get it to match, when I switched to fiberglass, i was able to get it perfect.
here is a pic of my quad spider
please let me know what you think, I would like to offer these for sale but am unsure of the popularity of quads, whats the wind loading on that, wow, its looks very heavy duty
Rick
Last edited:
I read somewhere that PVC and CPVC pipe has electrical conductivity properties.
the first quad I built, used PVC pipe and could not get it to match, when I switched to fiberglass, i was able to get it perfect.
here is a pic of my quad spider
please let me know what you think, I would like to offer these for sale but am unsure of the popularity of quads
Rick
You must have had something wrong that you missed. Myself and many others have built VHF and UHF quads using PVC without any problems and if the PVC was going to be an issue in any way it would show up on VHF long before HF.
There are a number of different kinds of PVC. The difference is in the mix used, some do contain more conductive 'stuff' than others, and is usually distinguished by color. I have used some, a grey'ish looking stuff, that really was a little conductive, not a lot, but some. I've found that the white stuff is typically an insulator. I have no idea if the different kinds are of any particular brand, the sales people where I got it didn't know either. It isn't just PVC pipe, almost all synthetics have varying degrees of conductivity and are usually of a different color. I figure it has to do with the dye used? One such example it the nylon cord found in the fishing section of stores. The white stuff works as an insulator, the 'green' stuff when wet, conducts to some degree. Who knows, it may be just the stuff you find around here, the 'arm-pit' of the country...
- 'Doc
- 'Doc
In due time I will likely build another quad.
The only thing I can say about the SWR using PVC as a component of the antenna is what I experienced:
28.755 --------- 1.7:1
28.305 --------- 1.2:1
27.855 --------- 1.2:1
27.405 --------- 1.2:1
26.965 --------- 1.1:1
26.515 --------- 1.0:1
26.065 --------- 1.5:1
25.615 --------- 4.0:1
I made a lot of local and DX contacts with it. I set it up Vertically polarized.
The only thing I can say about the SWR using PVC as a component of the antenna is what I experienced:
28.755 --------- 1.7:1
28.305 --------- 1.2:1
27.855 --------- 1.2:1
27.405 --------- 1.2:1
26.965 --------- 1.1:1
26.515 --------- 1.0:1
26.065 --------- 1.5:1
25.615 --------- 4.0:1
I made a lot of local and DX contacts with it. I set it up Vertically polarized.
Yea Doc,
Yea, their are thousands of articles all over the web stating the conductive properties of PVC, and I cannot believe I fell for my local mud ducks telling me " hell I use it all the time and mine works ok " Then when I ask them how they measured their performance they said well my buddy down the street said it sounded good, therefore it must have been working OK..... Anyways, I'm now NOT listing to them anymore. My PVC one worked, but I could not get the inductance of the antenna down to zero, when I switched to fiberglass, It worked so much better, and I was able to get the J zero number down to zero.I guess some enjoy being stuck in the mud...
anyways thanks for the info, I'm gonna offer them for sale and see what happens, when I first hooked it up, I thought something was wrong, their was NO static in the receive... I LOVE IT
Talk to ya later
Rick
Hey homerbb,
What was the J number on your antenna analyzer ?
I got low SWR numbers also on the one I built with PVC, very similar SWR to what you got, But the inductance and capacitance was WAY OFF.
And I'm sure you understand the importance of inductance / capacitance ( some people call it resonance ) of the antenna.
Please let me know your results, I would like to compare notes, maybe I had some goofed up..
Rick
I do understand the importance of resonance, however I'm unable to supply you that information as I don't have it. I don't own an analyzer; I did get great performance from the antenna.
Built a 4 element quad for 11 meters in the late 70's. With pvc pip and electrical boxes as the hubs. Man that thing worked like a charm. I love quad antennas. Have used them on 2 meters and 70 cm also.
I later switched to the quagi antenna. I built a dual band 2meter/70cm 6 years ago, but lost it in a storm last year.
http://www.gokarters.com/vbforum/attachment.php?attachmentid=504&stc=1&d=1181618960
http://www.gokarters.com/vbforum/attachment.php?attachmentid=503&stc=1&d=1181618954
I later switched to the quagi antenna. I built a dual band 2meter/70cm 6 years ago, but lost it in a storm last year.
http://www.gokarters.com/vbforum/attachment.php?attachmentid=504&stc=1&d=1181618960
http://www.gokarters.com/vbforum/attachment.php?attachmentid=503&stc=1&d=1181618954
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