[Repeater-Builder] DB antenna question
I'm running out of usable antenna mounting space here and was wondering if anyone has tried to do the folloing and with what results : 1. Superimpose a complete set of DB420 elements with the harness on a DB224 antenna mast, where both antennas arrays were active and each fed by its own rptr./duplexer. The elements on each band would be offset 90 degrees from each other. 2. Split a DB420 and feed the top half and bottom half independently with separate feedlines,rptrs and duplexers. I realize I would lose some antenna gain (9.2 Db to 6 Db) and some filter cavities for each system might be required. 3. Super impose a second set of DB420 elements, with independet feed line, on an existing DB420 antenna, but offset 90 degrees from the original set. If combining antennas as posed above is practical then I could gain additional space for 1 or more additional rptr's. or at least I could make the site look a little less cluttered. Thanks in advance for any constructive comments. Doug N3DAB/WPRX486/WPJL709
RE: [Repeater-Builder] DB antenna question
Jeff, Chuck, Larry and John Thanks for the responses. I new about DB making the U/V version but not about the U/U or V/V version. I think I'll opt. for converting mine to U/U and sacrifice a little gain, but maybe improve some of the lcoal coverage with better tilt down characteristics from my site. Jeff - additional filtering is not a problem here. I have a bunch of Mot. T1500 series cans available for that and several UHF isolators also. Chuck re: my last message to you and the pigtails - the intent of the question was to keep the lower harness still viable for returning to the original configuration if I needed to. Cutting a TEE off doesn't let me return it to its original operation. Again thanks for the imput and all other comment you may have. -- Doug N3DAB/WPRX486/WPJL709 Jeff DePolo [EMAIL PROTECTED] wrote: = 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna. Better idea. This used to be order-able as a DB420D, which was really two DB408's on the same mast, one stacked above the other, with the feeders for both antennas terminating at the bottom. The isolation between antennas was something like 30 dB, so again, you'll still need adequate filtering downstairs. --- Jeff WN3A
Re: [Repeater-Builder] DB antenna question
The only way to use the lower harness and still salvage/save for later is to put a dummy load on the connector where the top half of the antenna connected. Kind of ruins the efficiency. Chuck WB2EDV - Original Message - Subject: RE: [Repeater-Builder] DB antenna question Chuck re: my last message to you and the pigtails - the intent of the question was to keep the lower harness still viable for returning to the original configuration if I needed to. Cutting a TEE off doesn't let me return it to its original operation. Again thanks for the imput and all other comment you may have. -- Doug N3DAB/WPRX486/WPJL709
Re: [Repeater-Builder] DB antenna question
Chuck thanks again. I thought that would be the case. I'll try putting the splice in the lower section as you suggested and saving the the bottom TEE (with the orignal pigtail) for returning to the original configuration if needed, Just more tape and water proofing required to reinstall. -- Doug N3DAB/WPRX486/WPJL709 Chuck Kelsey [EMAIL PROTECTED] wrote: = The only way to use the lower harness and still salvage/save for later is to put a dummy load on the connector where the top half of the antenna connected. Kind of ruins the efficiency. Chuck WB2EDV - Original Message - Subject: RE: [Repeater-Builder] DB antenna question Chuck re: my last message to you and the pigtails - the intent of the question was to keep the lower harness still viable for returning to the original configuration if I needed to. Cutting a TEE off doesn't let me return it to its original operation. Again thanks for the imput and all other comment you may have. -- Doug N3DAB/WPRX486/WPJL709
Re: [Repeater-Builder] DB antenna question
Yep, you could add another connector to the cut-off parts and re-connect later if needed. - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Cc: Chuck Kelsey [EMAIL PROTECTED] Sent: Friday, October 24, 2008 3:35 PM Subject: Re: [Repeater-Builder] DB antenna question Chuck thanks again. I thought that would be the case. I'll try putting the splice in the lower section as you suggested and saving the the bottom TEE (with the orignal pigtail) for returning to the original configuration if needed, Just more tape and water proofing required to reinstall. -- Doug N3DAB/WPRX486/WPJL709 Chuck Kelsey [EMAIL PROTECTED] wrote: = The only way to use the lower harness and still salvage/save for later is to put a dummy load on the connector where the top half of the antenna connected. Kind of ruins the efficiency. Chuck WB2EDV - Original Message - Subject: RE: [Repeater-Builder] DB antenna question Chuck re: my last message to you and the pigtails - the intent of the question was to keep the lower harness still viable for returning to the original configuration if I needed to. Cutting a TEE off doesn't let me return it to its original operation. Again thanks for the imput and all other comment you may have. -- Doug N3DAB/WPRX486/WPJL709 Yahoo! Groups Links
[Repeater-Builder] DB antenna question
I'm running out of antenna mounting positions at my site. Has anyone tried any of the following ideas and if so what were the results ? The intent here is to run 2 rptrs. using a common mast to support 2 antennas. 1. Mounting the dipoles and harness from a UHF DB420 on the same mast as a VHF DB224, or vice versa. (UHF and VHF antennas on the same mast) 2. Mounting the dipoles and harness from a DB420 on the same mast of an existing DB420.(2-DB420 UHF antennas on the same mast) 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna. In 1. and 2. the dipoles of each antenna would be at right angles to the existing antenna. In 3. the overall gain of the single antenna would be reduced to about 6 Db for the upper and lower halves. Additionally extra filter cavities would probably be required to keep the 2 rptrs. using the antennas from interfering with each other. If any of the above ideas are practical this would allow me to recoup some additonal mounting positions or at the least reduce the clutter of antennas I have now. All constructive comments will be appreciated. Doug N3DAB/WPRX486/WPJL709
Re: [Repeater-Builder] DB antenna question
You should be able to utilize the lower section harness as well. Chuck WB2EDV - Original Message - 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna.
Re: [Repeater-Builder] DB antenna question
they have made them in the past DB John - Original Message - From: n3dab To: Repeater-Builder@yahoogroups.com Sent: Thursday, October 23, 2008 8:06 PM Subject: [Repeater-Builder] DB antenna question I'm running out of antenna mounting positions at my site. Has anyone tried any of the following ideas and if so what were the results ? The intent here is to run 2 rptrs. using a common mast to support 2 antennas. 1. Mounting the dipoles and harness from a UHF DB420 on the same mast as a VHF DB224, or vice versa. (UHF and VHF antennas on the same mast) 2. Mounting the dipoles and harness from a DB420 on the same mast of an existing DB420.(2-DB420 UHF antennas on the same mast) 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna. In 1. and 2. the dipoles of each antenna would be at right angles to the existing antenna. In 3. the overall gain of the single antenna would be reduced to about 6 Db for the upper and lower halves. Additionally extra filter cavities would probably be required to keep the 2 rptrs. using the antennas from interfering with each other. If any of the above ideas are practical this would allow me to recoup some additonal mounting positions or at the least reduce the clutter of antennas I have now. All constructive comments will be appreciated. Doug N3DAB/WPRX486/WPJL709
RE: [Repeater-Builder] DB antenna question
1. Mounting the dipoles and harness from a UHF DB420 on the same mast as a VHF DB224, or vice versa. (UHF and VHF antennas on the same mast) There will be a lot of interaction between the two. I wouldn't do this. You'd also likely need extra filtering on the ground between the VHF and UHF repeaters since the coupling between antennas will be very high. 2. Mounting the dipoles and harness from a DB420 on the same mast of an existing DB420.(2-DB420 UHF antennas on the same mast) Really bad idea. At that point, you may as well just use one antenna and a combiner/multicoupler at the bottom - you'd likely need almost the same amount of filtering with the two antennas separated on the same mast because there will be so much coupling. 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna. Better idea. This used to be order-able as a DB420D, which was really two DB408's on the same mast, one stacked above the other, with the feeders for both antennas terminating at the bottom. The isolation between antennas was something like 30 dB, so again, you'll still need adequate filtering downstairs. If any of the above ideas are practical this would allow me to recoup some additonal mounting positions or at the least reduce the clutter of antennas I have now. Can you mount two antennas on the same mount, one rightside-up, and the other inverted? If you do this, be careful if you invert-mount a DB420. The mechanical connection in the center relies somewhat on gravity to keep the two halves together; if you invert-mount, gravity is working against you. --- Jeff WN3A
Re: [Repeater-Builder] DB antenna question
How do you suggest terminating the connector that normally connects to the top half. Just seal it water tight ? -- Doug N3DAB/WPRX486/WPJL709 Chuck Kelsey [EMAIL PROTECTED] wrote: = You should be able to utilize the lower section harness as well. Chuck WB2EDV - Original Message - 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna.
RE: [Repeater-Builder] DB antenna question
Thanks Jeff. OK, idea 1. and 2. are basically shot down in flames. Idea 3. I can handle. Again the question, if I use the original harness how do I terminate the connector where the lower section joined the upper. Just weather proof it ?? Answer to your last comment is no All my antennas are mounted on 2 GI pipe, bracketed to the side of the house, that run from the ground to approx. 5' above the roof line (25'+/-). My site is my house located on top of a small mountain (2750'AMSL) roughly 1000' above average surrounding terrain. I also have covenents to deal with (no towers). Average coverage has been approx. 40+ miles where not blocked by higher terrain from my NW to NE. Roger on the gravity connection bit on the 2 have but a 3/8-1/2SS bolt thru the joint would solve that problem. -- Doug N3DAB/WPRX486/WPJL709 Jeff DePolo [EMAIL PROTECTED] wrote: = 1. Mounting the dipoles and harness from a UHF DB420 on the same mast as a VHF DB224, or vice versa. (UHF and VHF antennas on the same mast) There will be a lot of interaction between the two. I wouldn't do this. You'd also likely need extra filtering on the ground between the VHF and UHF repeaters since the coupling between antennas will be very high. 2. Mounting the dipoles and harness from a DB420 on the same mast of an existing DB420.(2-DB420 UHF antennas on the same mast) Really bad idea. At that point, you may as well just use one antenna and a combiner/multicoupler at the bottom - you'd likely need almost the same amount of filtering with the two antennas separated on the same mast because there will be so much coupling. 3. Taking an existing DB420 antenna and feeding the upper and lower halves with separate feedlines to make 2-6 Db antennas on the same mast. The lower harness section would be replaced with with the upper harness section from a junk antenna. Better idea. This used to be order-able as a DB420D, which was really two DB408's on the same mast, one stacked above the other, with the feeders for both antennas terminating at the bottom. The isolation between antennas was something like 30 dB, so again, you'll still need adequate filtering downstairs. If any of the above ideas are practical this would allow me to recoup some additonal mounting positions or at the least reduce the clutter of antennas I have now. Can you mount two antennas on the same mount, one rightside-up, and the other inverted? If you do this, be careful if you invert-mount a DB420. The mechanical connection in the center relies somewhat on gravity to keep the two halves together; if you invert-mount, gravity is working against you. --- Jeff WN3A
