[Repeater-Builder] Re: DB Products VHF UHF on same mast?
Hi Jim, Thanks for the info. I will probably not put the 440 antenna up - I don't plan on having a 440 repeater out here, just need to receive a control signal. So I'll probably put the diplexer at the bottom just use the db-224 for 440 receive. Tim W5FN --- In Repeater-Builder@yahoogroups.com, Jim Brown w5...@... wrote: I operate an antenna with a full size DB-224 and an 8 dipole 440 antenna on the same mast and found that the 2 meter transmitter does not bother the 440 receiver, but I do get some desense with the 440 transmitter into the 2 meter radio. An extra bandpass cavity on the 2 meter receiver cleared that up. GE Mastr II on both bands. I think that the 2 meter dipoles can absorb more power from the 440 antennas than the other way around, since the third harmonic is resonant on the 2 meter dipoles. I have also operated a DB-224 on 440 with some success. I tried a diplexer to combine the two antennas to one feedline without much success. I wound up using a separate feedline for each antenna and it worked much better. 73 - Jim W5ZIT --- On Mon, 7/20/09, tahrens301 tahr...@... wrote: From: tahrens301 tahr...@... Subject: [Repeater-Builder] DB Products VHF UHF on same mast? To: Repeater-Builder@yahoogroups.com Date: Monday, July 20, 2009, 10:11 PM I've got a DB-224 that is going up the tower in a while when I get the hardline, but control issues have changed from land line to 440mhz control. So I need 2 antennas. Today I saw a hybrid DB antenna, effectively a 224, plus a 16 element DB, all on the same mast. Is this something that can be done without having each antenna interact with the other? Sounds like a good idea to me. Just curious, Thanks, Tim W5FN
Re: [Repeater-Builder] Re: DB Products VHF UHF on same mast?
Someone on this list published an analysis of a DB-224 used on 440 and it showed some interesting results. The antenna exhibits a bunch of narrow lobes in the vertical plain, and has a very narrow vertical angle right on the horizon. For your purpose, I think you will find that it will work just fine with the diplexer at the repeater end splitting the antenna to the repeater and a 440 receiver. We operated a 2 meter and a 440 repeater through a diplexer to a Comet dual band antenna and as long as the two frequencies were not harmonically related, the two repeaters seemed to get along just fine on the one antenna. 73 - Jim W5ZIT --- On Wed, 7/22/09, tahrens301 tahr...@swtexas.net wrote: From: tahrens301 tahr...@swtexas.net Subject: [Repeater-Builder] Re: DB Products VHF UHF on same mast? To: Repeater-Builder@yahoogroups.com Date: Wednesday, July 22, 2009, 10:17 AM Hi Jim, Thanks for the info. I will probably not put the 440 antenna up - I don't plan on having a 440 repeater out here, just need to receive a control signal. So I'll probably put the diplexer at the bottom just use the db-224 for 440 receive. Tim W5FN --- In Repeater-Builder@ yahoogroups. com, Jim Brown w5...@... wrote: I operate an antenna with a full size DB-224 and an 8 dipole 440 antenna on the same mast and found that the 2 meter transmitter does not bother the 440 receiver, but I do get some desense with the 440 transmitter into the 2 meter radio. An extra bandpass cavity on the 2 meter receiver cleared that up. GE Mastr II on both bands. I think that the 2 meter dipoles can absorb more power from the 440 antennas than the other way around, since the third harmonic is resonant on the 2 meter dipoles. I have also operated a DB-224 on 440 with some success. I tried a diplexer to combine the two antennas to one feedline without much success. I wound up using a separate feedline for each antenna and it worked much better. 73 - Jim W5ZIT --- On Mon, 7/20/09, tahrens301 tahr...@... wrote: From: tahrens301 tahr...@... Subject: [Repeater-Builder] DB Products VHF UHF on same mast? To: Repeater-Builder@ yahoogroups. com Date: Monday, July 20, 2009, 10:11 PM I've got a DB-224 that is going up the tower in a while when I get the hardline, but control issues have changed from land line to 440mhz control. So I need 2 antennas. Today I saw a hybrid DB antenna, effectively a 224, plus a 16 element DB, all on the same mast. Is this something that can be done without having each antenna interact with the other? Sounds like a good idea to me. Just curious, Thanks, Tim W5FN
[Repeater-Builder] Re: DB Products VHF UHF on same mast?
Hi Mike, It looks like this antenna is a DB-420B. It has 16 elements in groups of 2... 4 groups on the top 'half', and 4 on the bottom. I was thinking of using only 1 run of hardline up the tower putting a duplexer up at the top (and one at the bottom). Thanks, Tim W5FN --- In Repeater-Builder@yahoogroups.com, Mike Mullarkey k7...@... wrote: If you have a VHF 224 just take a DB411 UHF and mount on the opposite side of the mast 180deg from the VHF loops. We do it all the time out here and works great. Just run two coax cables and all is nice and neat. Best of both worlds, you get two antennas on the same mast without using another 10 or so feet of tower space. There is only one catch, you may want to top support the DB224 antenna since you are adding additional loops. Mike Mike Mullarkey K7PFJ 6886 Sage Ave Firestone, Co 80504 303-954-9695 Home 303-954-9693 Home Office Fax 303-718-8052 Cellular From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Monday, July 20, 2009 9:11 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB Products VHF UHF on same mast? I've got a DB-224 that is going up the tower in a while when I get the hardline, but control issues have changed from land line to 440mhz control. So I need 2 antennas. Today I saw a hybrid DB antenna, effectively a 224, plus a 16 element DB, all on the same mast. Is this something that can be done without having each antenna interact with the other? Sounds like a good idea to me. Just curious, Thanks, Tim W5FN No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.20/2251 - Release Date: 07/20/09 18:29:00
RE: [Repeater-Builder] Re: DB Products VHF UHF on same mast?
Tim, If you're just using it for control, you only need to receive on uhf. Just put up the 224 for the duplex vhf on the one feed line. Downstairs use a diplexer to pull off your uhf control receiver signal. It should work fine at that location. We used to have a short link path to a site like that for years. 73 Don W5DK -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Tuesday, July 21, 2009 9:54 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: DB Products VHF UHF on same mast? Hi Mike, It looks like this antenna is a DB-420B. It has 16 elements in groups of 2... 4 groups on the top 'half', and 4 on the bottom. I was thinking of using only 1 run of hardline up the tower putting a duplexer up at the top (and one at the bottom). Thanks, Tim W5FN --- In Repeater-Builder@yahoogroups.com, Mike Mullarkey k7...@... wrote: If you have a VHF 224 just take a DB411 UHF and mount on the opposite side of the mast 180deg from the VHF loops. We do it all the time out here and works great. Just run two coax cables and all is nice and neat. Best of both worlds, you get two antennas on the same mast without using another 10 or so feet of tower space. There is only one catch, you may want to top support the DB224 antenna since you are adding additional loops. Mike Mike Mullarkey K7PFJ 6886 Sage Ave Firestone, Co 80504 303-954-9695 Home 303-954-9693 Home Office Fax 303-718-8052 Cellular From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Monday, July 20, 2009 9:11 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB Products VHF UHF on same mast? I've got a DB-224 that is going up the tower in a while when I get the hardline, but control issues have changed from land line to 440mhz control. So I need 2 antennas. Today I saw a hybrid DB antenna, effectively a 224, plus a 16 element DB, all on the same mast. Is this something that can be done without having each antenna interact with the other? Sounds like a good idea to me. Just curious, Thanks, Tim W5FN No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.392 / Virus Database: 270.13.20/2251 - Release Date: 07/20/09 18:29:00 Yahoo! Groups Links
[Repeater-Builder] Re: DB Products VHF UHF on same mast?
Hi Mike - it's only a receiver. Tim --- In Repeater-Builder@yahoogroups.com, Mike Morris WA6ILQ wa6...@... wrote: Is your control a receive only, or is it a UHF control repeater? I've seen a 2m antenna used to feed both a 2m receiver and a UHF receiver. After all, the third harmonic of 147 MHz is 441 mhz. At 08:11 PM 07/20/09, you wrote: I've got a DB-224 that is going up the tower in a while when I get the hardline, but control issues have changed from land line to 440mhz control. So I need 2 antennas. Today I saw a hybrid DB antenna, effectively a 224, plus a 16 element DB, all on the same mast. Is this something that can be done without having each antenna interact with the other? Sounds like a good idea to me. Just curious, Thanks, Tim W5FN Yahoo! Groups Links
