I have experimented with both non-metallic and metallic cross booms after reading numerous articles on the subject some years ago. With CP antennae mounted in X configuration there seems to be hardly any difference in performance. I speak of experiments done when AO-40 was active.
I now use a metallic boom as it gives very good rigidity to mount two CP antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not have the option to order a good section of fibre glass cross boom any way, and so had made do with PVC tube wrapped in fibre glass, but it eventually sagged and I had to periodically rotate it 180 degrees to keep it somewhat level.
Gopal VU2GMN
Gopal,
A good decision that you made. A study by Kent, WA5VJB, shows that only some sensitivity of position between elements on the antenna boom impacts using a metal crossboom if the antenna is mounted in the "X" confinguration. My satellite antennas are mounted this way.
73 Ed - KL7UW
At 05:50 PM 4/5/2008, Gopal Madhavan wrote:
I have experimented with both non-metallic and metallic cross booms after reading numerous articles on the subject some years ago. With CP antennae mounted in X configuration there seems to be hardly any difference in performance. I speak of experiments done when AO-40 was active.
I now use a metallic boom as it gives very good rigidity to mount two CP antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not have the option to order a good section of fibre glass cross boom any way, and so had made do with PVC tube wrapped in fibre glass, but it eventually sagged and I had to periodically rotate it 180 degrees to keep it somewhat level.
Gopal VU2GMN
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi I got the thick wall Blue PVC pipes used for plumbing wrapped in fibreglass mat and its been in use for over ten years now. The final OD is now about 40mm. It does support both my cross yagis on the rotator. I am also looking for the fibreglass tube with thick wall and hope to get some here in Bangalore and will keep you informed Gopal. Best 73 Pop VU2POP
Gopal,
A good decision that you made. A study by Kent, WA5VJB, shows that only some sensitivity of position between elements on the antenna boom impacts using a metal crossboom if the antenna is mounted in the "X" confinguration. My satellite antennas are mounted this way.
73 Ed - KL7UW
At 05:50 PM 4/5/2008, Gopal Madhavan wrote:
I have experimented with both non-metallic and metallic cross booms after reading numerous articles on the subject some years ago. With CP antennae mounted in X configuration there seems to be hardly any difference in performance. I speak of experiments done when AO-40 was active.
I now use a metallic boom as it gives very good rigidity to mount two CP antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not have the option to order a good section of fibre glass cross boom any way, and so had made do with PVC tube wrapped in fibre glass, but it eventually sagged and I had to periodically rotate it 180 degrees to keep it somewhat level.
Gopal VU2GMN
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Suggestion, Wood has very good strength, why not place a wood dowel rod inside a pvc pipe with end caps to keep the weather out? THe wood will offer the support and the pvc will protect the wood from the elements.
Art , KC6UQH ----- Original Message ----- From: "Prathap Kumar" [email protected] To: [email protected] Sent: Sunday, April 06, 2008 7:44 AM Subject: [amsat-bb] Re: metal or non metal cross booms
Hi I got the thick wall Blue PVC pipes used for plumbing wrapped in fibreglass mat and its been in use for over ten years now. The final OD is now about 40mm. It does support both my cross yagis on the rotator. I am also looking for the fibreglass tube with thick wall and hope to get some here in Bangalore and will keep you informed Gopal. Best 73 Pop VU2POP
Gopal,
A good decision that you made. A study by Kent, WA5VJB, shows that only some sensitivity of position between elements on the antenna boom impacts using a metal crossboom if the antenna is mounted in the "X" confinguration. My satellite antennas are mounted this way.
73 Ed - KL7UW
At 05:50 PM 4/5/2008, Gopal Madhavan wrote:
I have experimented with both non-metallic and metallic cross booms after reading numerous articles on the subject some years ago. With CP antennae mounted in X configuration there seems to be hardly any difference in performance. I speak of experiments done when AO-40 was active.
I now use a metallic boom as it gives very good rigidity to mount two CP antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not have the option to order a good section of fibre glass cross boom any way, and so had made do with PVC tube wrapped in fibre glass, but it eventually sagged and I had to periodically rotate it 180 degrees to keep it somewhat level.
Gopal VU2GMN
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I have done that in the past and it works rather well. However, PVC gets extremely brittle over time from UV. Be sure to give it a good paint job with some form of marine paint (anti-UV) to help preserve it. I used on for 10 years and it was still good and give it to someone once I went to a solid fiberglass unit. Once the PVC becomes brittle, you'll not be able to tighten u-bolts down very tight.
I do not remember where or who, but I bought a solid 10 foot piece of fiberglass boom 1 1/2 inch in diameter from a place in Ohio. Since UPS would only allow up to 9 feet long, the company cut 1 foot of it off and shipped it (including the one foot remaining). I painted it with a UV resistant paint and it is still in use for my KLM antennas. The unit cost about $35.00. Not sure what the cost would be now. You can also check with your local marina or marine supply for fiberglass masting of various sizes.
I have also used the metal boom and had the arrays at 45 degrees to the boom and the elements and it seem to work with little impact on performance.
Reid, W4UPD
kc6uqh wrote:
Suggestion, Wood has very good strength, why not place a wood dowel rod inside a pvc pipe with end caps to keep the weather out? THe wood will offer the support and the pvc will protect the wood from the elements.
Art , KC6UQH ----- Original Message ----- From: "Prathap Kumar" [email protected] To: [email protected] Sent: Sunday, April 06, 2008 7:44 AM Subject: [amsat-bb] Re: metal or non metal cross booms
Hi I got the thick wall Blue PVC pipes used for plumbing wrapped in fibreglass mat and its been in use for over ten years now. The final OD is now about 40mm. It does support both my cross yagis on the rotator. I am also looking for the fibreglass tube with thick wall and hope to get some here in Bangalore and will keep you informed Gopal. Best 73 Pop VU2POP
Gopal,
A good decision that you made. A study by Kent, WA5VJB, shows that only some sensitivity of position between elements on the antenna boom impacts using a metal crossboom if the antenna is mounted in the "X" confinguration. My satellite antennas are mounted this way.
73 Ed - KL7UW
At 05:50 PM 4/5/2008, Gopal Madhavan wrote:
I have experimented with both non-metallic and metallic cross booms after reading numerous articles on the subject some years ago. With CP antennae mounted in X configuration there seems to be hardly any difference in performance. I speak of experiments done when AO-40 was active.
I now use a metallic boom as it gives very good rigidity to mount two CP antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not have the option to order a good section of fibre glass cross boom any way, and so had made do with PVC tube wrapped in fibre glass, but it eventually sagged and I had to periodically rotate it 180 degrees to keep it somewhat level.
Gopal VU2GMN
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (5)
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Edward Cole -
Gopal Madhavan -
kc6uqh -
Prathap Kumar -
w4upd