All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
Max Gain Systems might work for you as a fiberglass wholesaler, depending on your definition of "reasonable price".
de KM1P Joe
________________________________________ From: AMSAT-BB [email protected] on behalf of Tony via AMSAT-BB [email protected] Sent: Tuesday, November 24, 2020 7:00 PM To: AMSAT-BB Subject: [amsat-bb] Fiberglass Cross-boom Alternative?
All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
Tony,
This side fiberglass tube for booms not available and importing same quite expensive.
You may do it yourself for a fraction of the commercial cost using PVC (non-pressure) tube as a mould and using glass 2/4 coats of fiberglass matt 300grm/m2 for strength and for finishing surface matt and plenty of resin or epoxy. sanding between the coats will be required to get it good looking
I made one to support a long VHF LF cross Yagi about 7m long and another OM here Patrice (3B8FA) for HF Quad boom and spreader (fiberglass over bambous former).
However working fiberglass may repel some as “dirty” work and particularly when sanding it as the powder may get you scratching yourself for the night, just use some vaseline over you exposed body part to avoid same.
Hope this helps.
73
Jean Marc
On Nov 25, 2020, at 4:49 AM, Joseph B. Fitzgerald via AMSAT-BB [email protected] wrote:
Max Gain Systems might work for you as a fiberglass wholesaler, depending on your definition of "reasonable price".
de KM1P Joe
From: AMSAT-BB [email protected] on behalf of Tony via AMSAT-BB [email protected] Sent: Tuesday, November 24, 2020 7:00 PM To: AMSAT-BB Subject: [amsat-bb] Fiberglass Cross-boom Alternative?
All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
On 2020-11-24 7:00 p.m., Tony via AMSAT-BB wrote:
alternative to fiberglass cross booms?
I took a length of electrical PVC conduit 1.5 inch and put a wooden dowel inside it. It was a tight fit but I ground some off to make it slide in with a bit of force (hammer). The dowel was coated with a light 50/50 alcohol/shalac rubbed on with a cloth. It is still in use after maybe 20 years.
I am not 100% sure about the wooden dowel. I may have use something smaller than the inside of the PVC and only drove in a piece at each end that was tight. It was wood though.
Don't dismiss using a metal cross-boom. People say it won't work without actually examining the problem. When antenna guru Kent Britain, WA5VJB looked at the problem he found a metal boom to work quite well. He then tested it on the antenna range and verified it worked. You can see the paper he presented at an AMSAT symposium here: http://www.kk0sd.net/metalboom/metalboom.htm
When I had a permanent satellite station I used a metal cross-boom, and there were several others in the OSCAR-13 and AO-40 era that did.
73, Gary "Joe", kk0sd
-----Original Message----- From: AMSAT-BB [email protected] On Behalf Of Tony via AMSAT-BB Sent: Tuesday, November 24, 2020 6:00 PM To: AMSAT-BB [email protected] Subject: [amsat-bb] Fiberglass Cross-boom Alternative?
All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
All:
Thanks for all the useful info on cross boom alternatives.
Tony -K2MO
I have tested the VJB paper in the real world on a metal cross boom (after having used fiberglass for years), and it worked just fine if you follow his instructions precisely. I used a 70cm M2 circularly polarized antenna (boom length about 10' or so, can't recall the model number) 73, N0AN Hasan
On Tue, Nov 24, 2020 at 10:50 PM Tony via AMSAT-BB [email protected] wrote:
All:
Thanks for all the useful info on cross boom alternatives.
Tony -K2MO
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
Gary,
Yes, many of us believe that having a metaling cross boom, boom or clamps has no significant effect on your Yagi, actually for most purposes I fully agree it is generally not noticeable.
Being a purist, I wish to state that theoretically any metal part within the antenna except the active element, including boom, clamps etc... affect the antenna theoretical performance. This is why I am presently building a UHF 4 x 30 ele. cross pol LFA Yagis array and a VHF 22 ele. cross pol VHF yagi. These antennas will have no metal parts except the active elements and the purpose is to be prepared or the future Lunar and eventually Mars repeaters, but also for own experimentation. All this not really require fo LEO’s anyway.
For info: when I started to study the LFA’s which is actually a superb concept and I already build a few to test same, with success using fiberglass booms. Originally when I contacted the supposed “inventor” which is inviting the OM’s to contact him for help on his Web site, it was frustrating as unfortunately he was too busy “making a living” thus did not help at all. Actually a blessing in disguise as thus I reversed engineered his design using the appropriate softwares and found many flaws in his claims (probably driven by commercial consideration), such as the metal boom having no effect, element support, worse his proposal for cross pol Yagis totally wrong conceptually, etc… In a nutshell the theoretical conclusion is that having no metal part in the LFA design will make a even better antenna that the “inventor” claims particularly for space com and low signal or in noisy QTH. The acid test will be done in a few months when all this will be on the roof here.
I already suggested a way to do cheap fiberglass booms and forgot to say that paint roller extension is also a cheap way to make fiberglass booms, just ensure that you have aluminium tube on the parts where you will clamps same secure some epoxy glue so that clamps do not crush it.
73
Jean Marc (3B8DU)
On Nov 25, 2020, at 7:03 AM, Gary via AMSAT-BB [email protected] wrote:
Don't dismiss using a metal cross-boom. People say it won't work without actually examining the problem. When antenna guru Kent Britain, WA5VJB looked at the problem he found a metal boom to work quite well. He then tested it on the antenna range and verified it worked. You can see the paper he presented at an AMSAT symposium here: http://www.kk0sd.net/metalboom/metalboom.htm
When I had a permanent satellite station I used a metal cross-boom, and there were several others in the OSCAR-13 and AO-40 era that did.
73, Gary "Joe", kk0sd
-----Original Message----- From: AMSAT-BB [email protected] On Behalf Of Tony via AMSAT-BB Sent: Tuesday, November 24, 2020 6:00 PM To: AMSAT-BB [email protected] Subject: [amsat-bb] Fiberglass Cross-boom Alternative?
All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
I got my 1/25" diameter solid fiberglass boom from www.MGS4U.com at what I think was a reasonable price. I painted it white to protect the finish and it's working quite well. I have three sat antennas on it: 70cm and 23cm on one side of the rotor and a 2m on the opposite side. To aid in clamping the antennas and the EL rotor to the boom, I cut appropriately-sized sections of PVC pipe to place at those clamping points. I then applied self-adhesive non-skid tread to the boom, attached the PVC sections over the non-skid tread, slid the fiberglass boom into the EL rotor, and attached the antennas. Seems to be working just fine.
On Tue, Nov 24, 2020 at 4:01 PM Tony via AMSAT-BB [email protected] wrote:
All:
Is there a cheaper non-metallic alternative to fiberglass cross booms? Or maybe a wholesale fiberglass rod distributor that has such a beast at a reasonable price?
Tony -K2MO
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
participants (7)
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Bill Booth -
Bob Hammond -
Gary -
Hasan N0AN -
Jean Marc Momple -
Joseph B. Fitzgerald -
Tony