RE: [Repeater-Builder] Lightning Rod (Bolt)?
Ah, OK Doug. I understand your project better now. I'm sure you'll find something that'll fit your needs. and you can keep the Super Stationmaster in mind for the new tower later. ;-) 73, Mark - N9WYS From: Repeater-Builder@yahoogroups.com On Behalf Of Doug Rehman Mark: I could probably come up with a used 9dB DB Products antenna, but for this application, weight is a MAJOR factor. A DB-809 is around 25 pounds and a DB-589 is still about 11 pounds. The 5dB gain Maxrad MFB9155 is less than 2 pounds. This is going on top of a 24' mast that is on top of a 54' tower. The mast already has multiple HF-1.2 GHz antennas, so loading is the major consideration. The DB-809 would equal about 600 pounds at the thrust bearing and the DB-859 would equal about 264 pounds- way more than the Maxrad. I'll eventually put up a second tower in the 100' range (I'm height limited due to a nearby 3800' grass strip airport) and will be able to go to something more substantial on it. For now, the Maxrad will have to suffice. This is for one of several 927 MHz repeaters that will be UHF linked. It doesn't need to have huge range, it is mainly to cover about a 10 mile radius. The other sites will be using DB Products antennas. Doug K4AC
RE: [Repeater-Builder] Lightning Rod (Bolt)?
Mark: I could probably come up with a used 9dB DB Products antenna, but for this application, weight is a MAJOR factor. A DB-809 is around 25 pounds and a DB-589 is still about 11 pounds. The 5dB gain Maxrad MFB9155 is less than 2 pounds. This is going on top of a 24' mast that is on top of a 54' tower. The mast already has multiple HF-1.2 GHz antennas, so loading is the major consideration. The DB-809 would equal about 600 pounds at the thrust bearing and the DB-859 would equal about 264 pounds- way more than the Maxrad. I'll eventually put up a second tower in the 100' range (I'm height limited due to a nearby 3800' grass strip airport) and will be able to go to something more substantial on it. For now, the Maxrad will have to suffice. This is for one of several 927 MHz repeaters that will be UHF linked. It doesn't need to have huge range, it is mainly to cover about a 10 mile radius. The other sites will be using DB Products antennas. Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mark Sent: Monday, November 02, 2009 8:31 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Lightning Rod (Bolt)? Doug, Not sure how soon you need this antenna, but if you have time to wait - go to Dayton next year. There has been a guy there the past two years selling RFS/Cellwave Super Stationmaster antennas. DEFINITELY commercial-grade. I bought one 2 years ago from the guy (I wish I could remember his name) but it cost me something like $80. still in the original shipping tube! Rated at 12.14 dBi (10 dBd). About 13.5 ft tall. He's in the flea market, behind the Arena, maybe one or two rows out. Someone else my know who he is, but he had a number of them both years, and on different freqs, so make sure you get one for 900-935 range (Model 10017-8). This one had Motorola numbers on it as well; I'm sure it was made for Motorola. NICE antenna!! Sinclair makes enclosed folded dipole antennas, but they are not full omni antennas - I use one on my station at the home QTH. It's a SRL411C4N, designed for 851-960. center freq of 930.. Happy antenna hunting.
RE: [Repeater-Builder] Lightning Rod (Bolt)?
Doug, Not sure how soon you need this antenna, but if you have time to wait - go to Dayton next year. There has been a guy there the past two years selling RFS/Cellwave Super Stationmaster antennas. DEFINITELY commercial-grade. I bought one 2 years ago from the guy (I wish I could remember his name) but it cost me something like $80. still in the original shipping tube! Rated at 12.14 dBi (10 dBd). About 13.5 ft tall. He's in the flea market, behind the Arena, maybe one or two rows out. Someone else my know who he is, but he had a number of them both years, and on different freqs, so make sure you get one for 900-935 range (Model 10017-8). This one had Motorola numbers on it as well; I'm sure it was made for Motorola. NICE antenna!! Sinclair makes enclosed folded dipole antennas, but they are not full omni antennas - I use one on my station at the home QTH. It's a SRL411C4N, designed for 851-960. center freq of 930.. Happy antenna hunting. Mark - N9WYS From: Repeater-Builder@yahoogroups.com On Behalf Of Doug Rehman I just looked at the TX/RX catalog - looks like you're referring to their CC Series antennas; the description indicate that the "lightning spike" (their term) is connected to a solid brass support pipe. They're not made for 900 MHz though, only UHF/700/800. Looks like the price for the 6dB gain version is around $2K. Their collinear description does not mention anything about a lightning spike, just "internal DC grounding for lightning protection and reduction of precipitation noise." It also occurs to me that the lightning spikes I've seen on 900 MHz DB Products antennas are not in the center of the cap, but offset to one side. They appear to be molded into the cap, not just part of the antenna passing thru it. Well I guess worst case, the Maxrad 900 antennas can be had fairly cheaply on eBay. I picked up 3 of the 6dB models for around $80 shipped. Much cheaper to replace than the Comet GP-15's! (Plus I've got a three year supply at my current lightning strike rate.) Doug K4AC
RE: [Repeater-Builder] Lightning Rod (Bolt)?
Is it just possible that it's for corona discharge :) John
RE: [Repeater-Builder] Lightning Rod (Bolt)?
I just looked at the TX/RX catalog - looks like you're referring to their CC Series antennas; the description indicate that the "lightning spike" (their term) is connected to a solid brass support pipe. They're not made for 900 MHz though, only UHF/700/800. Looks like the price for the 6dB gain version is around $2K. Their collinear description does not mention anything about a lightning spike, just "internal DC grounding for lightning protection and reduction of precipitation noise." It also occurs to me that the lightning spikes I've seen on 900 MHz DB Products antennas are not in the center of the cap, but offset to one side. They appear to be molded into the cap, not just part of the antenna passing thru it. Well I guess worst case, the Maxrad 900 antennas can be had fairly cheaply on eBay. I picked up 3 of the 6dB models for around $80 shipped. Much cheaper to replace than the Comet GP-15's! (Plus I've got a three year supply at my current lightning strike rate.) Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Monday, November 02, 2009 7:05 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Lightning Rod (Bolt)? I haven't seen any for that band either, but don't know what they utilize for the various panel antennas that are covered with a radome. TX/RX makes a vertical that has integral folded dipoles and an aluminum extrusion goes all the way to the tip of the antenna for lightning. I suspect it might survive a direct hit. To look at it, you'd think is was just one more fiberglass collinear. I'm pretty sure it's available in both 800 and 900, but it won't be cheap. Chuck WB2EDV - Original Message - From: Doug Rehman <mailto:d...@k4ac.com> To: Repeater-Builder@yahoogroups.com Sent: Monday, November 02, 2009 6:59 PM Subject: RE: [Repeater-Builder] Lightning Rod (Bolt)? I was told by someone that took an antenna out of the radome that there did not appear to be any connection to the conductor on the cap. The antenna slid right out of the bottom of the radome. I agree about the survivability of folded dipole arrays, but they don't seem to be an option at 900 MHz- at least I don't see them in commercial catalogs and have never encountered an 800 or 900 MHz. Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Monday, November 02, 2009 6:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Lightning Rod (Bolt)? Although I've never had one apart, I believe the cap is attached to the radiating element. Also, I have never seen any fiberglass collinear antenna survive a direct hit. I have, however, seen folded dipole arrays survive a lightning strike. Chuck WB2EDV - Original Message - From: "Doug Rehman" mailto:doug%40k4ac.com> > To: mailto:Repeater-Builder%40yahoogroups.com> > Sent: Monday, November 02, 2009 5:45 PM Subject: [Repeater-Builder] Lightning Rod (Bolt)? > Looking at some DB Products fiberglass radome antennas, they all have a > metal protrusion on the top cap; it looks like bronze perhaps. I presume > that it is some form of lightning mitigation device. Is this just a piece > of > metal in the cap, unattached to the internal antenna element? > > I'm curious as I need to mount a Maxrad 900 MHz antenna on top of a long > mast on the top of a tower. The tower takes a lightning hit about once a > year. The Maxrad is in PVC tubing and it'd probably be simple to add a > stainless bolt to the top of the antenna if it would do any good. > > The previous 3 antennas on top were Comet GP-15's. They have a thin metal > cap on the top of the radome. The first one took a pretty significant hit, > melting part of the cap and making a mess out of the antenna. The second > one > took a lesser hit, heating the element enough that it burned thru the > radome. The third strike was even less, just discoloring the fiberglass on > the top 8" of the radome. > > I know that I'd be better off with a DB Products antenna, but their weight > likely well exceeds the mast capability for a top antenna (where it needs > to > be). > > Thoughts??? > > Thanks, > DOUG > K4AC > > > > > > > > > > Yahoo! Groups Links > > > >
Re: [Repeater-Builder] Lightning Rod (Bolt)?
I haven't seen any for that band either, but don't know what they utilize for the various panel antennas that are covered with a radome. TX/RX makes a vertical that has integral folded dipoles and an aluminum extrusion goes all the way to the tip of the antenna for lightning. I suspect it might survive a direct hit. To look at it, you'd think is was just one more fiberglass collinear. I'm pretty sure it's available in both 800 and 900, but it won't be cheap. Chuck WB2EDV - Original Message - From: Doug Rehman To: Repeater-Builder@yahoogroups.com Sent: Monday, November 02, 2009 6:59 PM Subject: RE: [Repeater-Builder] Lightning Rod (Bolt)? I was told by someone that took an antenna out of the radome that there did not appear to be any connection to the conductor on the cap. The antenna slid right out of the bottom of the radome. I agree about the survivability of folded dipole arrays, but they don't seem to be an option at 900 MHz- at least I don't see them in commercial catalogs and have never encountered an 800 or 900 MHz. Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Monday, November 02, 2009 6:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Lightning Rod (Bolt)? Although I've never had one apart, I believe the cap is attached to the radiating element. Also, I have never seen any fiberglass collinear antenna survive a direct hit. I have, however, seen folded dipole arrays survive a lightning strike. Chuck WB2EDV - Original Message - From: "Doug Rehman" To: Sent: Monday, November 02, 2009 5:45 PM Subject: [Repeater-Builder] Lightning Rod (Bolt)? > Looking at some DB Products fiberglass radome antennas, they all have a > metal protrusion on the top cap; it looks like bronze perhaps. I presume > that it is some form of lightning mitigation device. Is this just a piece > of > metal in the cap, unattached to the internal antenna element? > > I'm curious as I need to mount a Maxrad 900 MHz antenna on top of a long > mast on the top of a tower. The tower takes a lightning hit about once a > year. The Maxrad is in PVC tubing and it'd probably be simple to add a > stainless bolt to the top of the antenna if it would do any good. > > The previous 3 antennas on top were Comet GP-15's. They have a thin metal > cap on the top of the radome. The first one took a pretty significant hit, > melting part of the cap and making a mess out of the antenna. The second > one > took a lesser hit, heating the element enough that it burned thru the > radome. The third strike was even less, just discoloring the fiberglass on > the top 8" of the radome. > > I know that I'd be better off with a DB Products antenna, but their weight > likely well exceeds the mast capability for a top antenna (where it needs > to > be). > > Thoughts??? > > Thanks, > DOUG > K4AC > > > > > > > > > > Yahoo! Groups Links > > > >
RE: [Repeater-Builder] Lightning Rod (Bolt)?
On most fiberglass omnis, the lighting spike at the top is an extension of the last element in the array which is actually a shorted quarter-wave section. This shorted quarter-wave section at the "far end" of the radiator serves to put the entire antenna at DC ground. Some of the cheaper fiberglass omnis have a little metal "cap" on the top, which isn't connected to anything, it's just there to seal the end of the fiberglass tube (examples: Diamond, Comet, Maxrad, Antenex, etc.). --- Jeff WN3A > -Original Message- > From: Repeater-Builder@yahoogroups.com > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey > Sent: Monday, November 02, 2009 6:43 PM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Lightning Rod (Bolt)? > > > > Although I've never had one apart, I believe the cap is > attached to the > radiating element. Also, I have never seen any fiberglass > collinear antenna > survive a direct hit. I have, however, seen folded dipole > arrays survive a > lightning strike. > > Chuck > WB2EDV > > - Original Message - > From: "Doug Rehman" mailto:doug%40k4ac.com> > > To: <mailto:Repeater-Builder%40yahoogroups.com> > > Sent: Monday, November 02, 2009 5:45 PM > Subject: [Repeater-Builder] Lightning Rod (Bolt)? > > > Looking at some DB Products fiberglass radome antennas, > they all have a > > metal protrusion on the top cap; it looks like bronze > perhaps. I presume > > that it is some form of lightning mitigation device. Is > this just a piece > > of > > metal in the cap, unattached to the internal antenna element? > > > > I'm curious as I need to mount a Maxrad 900 MHz antenna on > top of a long > > mast on the top of a tower. The tower takes a lightning hit > about once a > > year. The Maxrad is in PVC tubing and it'd probably be > simple to add a > > stainless bolt to the top of the antenna if it would do any good. > > > > The previous 3 antennas on top were Comet GP-15's. They > have a thin metal > > cap on the top of the radome. The first one took a pretty > significant hit, > > melting part of the cap and making a mess out of the > antenna. The second > > one > > took a lesser hit, heating the element enough that it > burned thru the > > radome. The third strike was even less, just discoloring > the fiberglass on > > the top 8" of the radome. > > > > I know that I'd be better off with a DB Products antenna, > but their weight > > likely well exceeds the mast capability for a top antenna > (where it needs > > to > > be). > > > > Thoughts??? > > > > Thanks, > > DOUG > > K4AC > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.423 / Virus Database: 270.14.43/2474 - Release > Date: 11/02/09 07:51:00 > > >
RE: [Repeater-Builder] Lightning Rod (Bolt)?
I was told by someone that took an antenna out of the radome that there did not appear to be any connection to the conductor on the cap. The antenna slid right out of the bottom of the radome. I agree about the survivability of folded dipole arrays, but they don't seem to be an option at 900 MHz- at least I don't see them in commercial catalogs and have never encountered an 800 or 900 MHz. Doug K4AC From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Monday, November 02, 2009 6:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Lightning Rod (Bolt)? Although I've never had one apart, I believe the cap is attached to the radiating element. Also, I have never seen any fiberglass collinear antenna survive a direct hit. I have, however, seen folded dipole arrays survive a lightning strike. Chuck WB2EDV - Original Message - From: "Doug Rehman" mailto:doug%40k4ac.com> > To: mailto:Repeater-Builder%40yahoogroups.com> > Sent: Monday, November 02, 2009 5:45 PM Subject: [Repeater-Builder] Lightning Rod (Bolt)? > Looking at some DB Products fiberglass radome antennas, they all have a > metal protrusion on the top cap; it looks like bronze perhaps. I presume > that it is some form of lightning mitigation device. Is this just a piece > of > metal in the cap, unattached to the internal antenna element? > > I'm curious as I need to mount a Maxrad 900 MHz antenna on top of a long > mast on the top of a tower. The tower takes a lightning hit about once a > year. The Maxrad is in PVC tubing and it'd probably be simple to add a > stainless bolt to the top of the antenna if it would do any good. > > The previous 3 antennas on top were Comet GP-15's. They have a thin metal > cap on the top of the radome. The first one took a pretty significant hit, > melting part of the cap and making a mess out of the antenna. The second > one > took a lesser hit, heating the element enough that it burned thru the > radome. The third strike was even less, just discoloring the fiberglass on > the top 8" of the radome. > > I know that I'd be better off with a DB Products antenna, but their weight > likely well exceeds the mast capability for a top antenna (where it needs > to > be). > > Thoughts??? > > Thanks, > DOUG > K4AC > > > > > > > > > > Yahoo! Groups Links > > > >
Re: [Repeater-Builder] Lightning Rod (Bolt)?
Although I've never had one apart, I believe the cap is attached to the radiating element. Also, I have never seen any fiberglass collinear antenna survive a direct hit. I have, however, seen folded dipole arrays survive a lightning strike. Chuck WB2EDV - Original Message - From: "Doug Rehman" To: Sent: Monday, November 02, 2009 5:45 PM Subject: [Repeater-Builder] Lightning Rod (Bolt)? > Looking at some DB Products fiberglass radome antennas, they all have a > metal protrusion on the top cap; it looks like bronze perhaps. I presume > that it is some form of lightning mitigation device. Is this just a piece > of > metal in the cap, unattached to the internal antenna element? > > I'm curious as I need to mount a Maxrad 900 MHz antenna on top of a long > mast on the top of a tower. The tower takes a lightning hit about once a > year. The Maxrad is in PVC tubing and it'd probably be simple to add a > stainless bolt to the top of the antenna if it would do any good. > > The previous 3 antennas on top were Comet GP-15's. They have a thin metal > cap on the top of the radome. The first one took a pretty significant hit, > melting part of the cap and making a mess out of the antenna. The second > one > took a lesser hit, heating the element enough that it burned thru the > radome. The third strike was even less, just discoloring the fiberglass on > the top 8" of the radome. > > I know that I'd be better off with a DB Products antenna, but their weight > likely well exceeds the mast capability for a top antenna (where it needs > to > be). > > Thoughts??? > > Thanks, > DOUG > K4AC > > > > > > > > > > Yahoo! Groups Links > > > >
