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eHam Forums => Antennas and Towers and more => Topic started by: KD0TLI on November 06, 2012, 08:15:04 PM



Title: Fiberglass rod/tube - for Cubical Quad
Post by: KD0TLI on November 06, 2012, 08:15:04 PM
I'd appreciate any info on sourcing materials and design tips any of you can pass along.

I just got my Technician class ticket, and I'd like to build a 3 or 4 element quad for 10 meter.
From what I've read I will need some fiberglass tubing or rod for the spreaders.

I've seen plenty of vendors on the web, but I'd prefer to get it from a HAM related vendor.

Thanks.
KD0TLI


Title: RE: Fiberglass rod/tube - for Cubical Quad
Post by: G4AON on November 07, 2012, 05:53:24 AM
Congratulations on your ticket.

I would try a 2 element to start with, they are cheap and easy to make and it will give you experience with a 3 dimensional antenna! I have built a couple of 10m 2 element quads in the past, I used a 4 foot 6" length of aluminium tubing for the boom, 3/4" tubes about 18" long in the form of an "X" at each end of the boom and bamboo garden canes for the spreaders. OK so the spreaders won't last, but it costs little and is easy to make, it will be a good experience too.

You can bolt the 3/4" aluminium tubes to the boom with with "U" bolts, or even TV aerial fixing clamps, the canes do not need much to secure them.

There are feed arrangements for a 2 element 6m quad on my web site (www.astromag.co.uk/quad), obviously you would need to scale up the 75 Ohm matching section from 6m to 10m. To save you working out dimensions for a 10m quad, an upscaled version for 28.5 MHz would be sized as below (from EZNec 4):

Driven element: 104.2" each side
Reflector: 110.9" each side
Spacing: 52.75"
Wire: 16g enamelled copper wire, or bare copper wire (not PVC insulated).
Feed impedance: 100 Ohm (use approx 68.6" of RG59 coax for a quarter wave matching network to 50 Ohm, check with an analyser if you have access to one).

SWR: 1.03:1 at 28.5 MHz, gain in free space 7.25 dBi, Front to back 23 dB

73 Dave


Title: RE: Fiberglass rod/tube - for Cubical Quad
Post by: K7KBN on November 07, 2012, 07:17:10 AM
Check out Cubex.  They sell whole antennas as kits, and the pieces are available separately.  For a 10 meter quad, of course, the spreaders won't be anywhere near the length of a typical tribander.  Have fun.

There's a very good book, "Cubical Quad Antennas", by Bill Orr and Stuart Cowan.  YOu'll find a lot of good reading there.


Title: RE: Fiberglass rod/tube - for Cubical Quad
Post by: VE1IDX on November 07, 2012, 02:05:30 PM
Check out Cubex.  They sell whole antennas as kits, and the pieces are available separately.  For a 10 meter quad, of course, the spreaders won't be anywhere near the length of a typical tribander.  Have fun.

There's a very good book, "Cubical Quad Antennas", by Bill Orr and Stuart Cowan.  YOu'll find a lot of good reading there.

That's a good start Pat. Another good place is Max Gain Systems. They have all you need for home brew quads. You just provide the design.

http://www.mgs4u.com/index.html (http://www.mgs4u.com/index.html)


Title: RE: Fiberglass rod/tube - for Cubical Quad
Post by: K4RVN on November 07, 2012, 02:23:50 PM
I think your best price and best selection would be max gain systems as in a previous post.
Check under fiberglass products to compare prices delivered with any other sources. They have a large selection and I saw them at the Atlanta hamfest with a lot of antenna products. A quad is a great antenna with a large footprint. I have had 4 so far.
http://www.mgs4u.com/index.html

Frank