Re: [Repeater-Builder] Duplexer vs Split Level Antennas
Allan, my mobile radio was a GE Progress line - either 30 or 60 Watts. I had both and don't remember which I used most of the time. The antenna at 1000 ft was connected to some kind of commercial solid state converter (which I don't recall) and 1000 ft of RG-58 (at 10 meters) carried the signal down the tower. The repeater was an elaborate system with the 146.34/94 as the main machine. There was at least one other open repeater on 146.16/76 which was for use in the Ft Worth area only. The transmitting antenna was on the west side of the tower and it was pretty much shielded from the east toward Dallas. Unfortunately, the receive antenna at 1000 ft prevented coordination of another 16/76 repeater for 150 miles to the east. At 90 miles we asked for 16/76 but were assigned the 'odd' frequency of 19/79. I think there were other 'private' repeaters as part of the system using CTCSS access. The trustee was Harold Reisor W5SXK and he had the hub for the system at his QTH. I never got to see any of the gear, but heard about it in bits and pieces over several years. As I understood it, each receiver connected to the 10 meter down converter was connected to a 420 transmitter linking to Harold's house. There he cross connected to a 420 link back to the transmitter site for each of the transmit frequencies. Interestingly enough, he also had a 94 receiver linked to his house, and one evening when we had some extended propagation, he linked the 94 receiver to the 94 transmitter. The Little Rock Arkansas 34/94 repeater was loud and clear on the 94 receiver in Ft Worth and although there was a honk each time a local station on the Ft Worth 94 repeater let up, as soon as another station keyed down on 34 he was repeated on 94 with no problem. This just illustrates how much isolation the 34/94 system in Ft Worth gained with the 500 ft separation on the receive and transmit antennas. The signal on 94 from Little Rock was that much stronger than the local transmitter on 94. As I understood it, the 34/94 repeater in Little Rock also had the capability (by the control op) of listening on 94 and retransmitting on 94 and several QSOs were had between stations in the coverage of the Ft Worth repeater with stations on the Little Rock repeater, with the two repeaters linked on 94. This is a recollection from back in the early '70s' in the last century so hope I have remembered it right. It was the most robust repeater we had in the area till they put up the big towers at Cedar Hill and a few repeaters gained access to antennas at 1500 ft. 73 - Jim W5ZIT --- On Fri, 1/29/10, allan crites wa9...@arrl.net wrote: From: allan crites wa9...@arrl.net Subject: Re: [Repeater-Builder] Duplexer vs Split Level Antennas To: Repeater-Builder@yahoogroups.com Date: Friday, January 29, 2010, 5:13 AM Jim That's a very interesting posting of the repeater(s) you were aware of and worked reliably from some 90 miles away in Texas. Perhaps you could provide us some of the parameters of the installation, like the receive antenna used at the 1000' level, the type converter used to convert the received signals to 10 M , the transmit antenna (any one will do) at 500', the coax used to connect it to the transmitter, and the PO of the transmitter. I'm not sure I understood you correctly about the coax downlead you indicated was connected to the receive antenna, was it RG-58 from the top of the tower to the receivers below or some other type coax? Also what was the PO of the GE mobile you were using? Thanks Allan Crites WA9ZZU
RE: [Repeater-Builder] Duplexer vs Split Level Antennas
Have chance to install a DB 224 at 450' and another one anywhere below it. Using LDF6 on both runs. RF solid state 110 watts out. Wanting to know the pros or cons of running both antenna close together for more height with duplexer or spacing antennas for isolation without duplexer? All other things being equal, I'd take split antennas over duplexing any day. But I'd never connect a transmitter (or a receiver for that matter) directly to an antenna without proper filtering. So if you're asking if it's OK to just connect the transmitter and receiver to separate antennas and let 'er rip, my answer would be no, don't do that. Assuming you already have a suitable duplexer, split it in half (remove the antenna tee), and use it as two separate filters to connect to the two separate antennas. Space the antennas some nominal amount (greater spacing = more isolation, but also more disparity between Tx and Rx coverage), and you'll do quite well and have far fewer issues and sources of aggrevation in the long run as compared to duplexing on a common antenna. --- Jeff WN3A
[Repeater-Builder] Duplexer vs Split Level Antennas
Have chance to install a DB 224 at 450' and another one anywhere below it. Using LDF6 on both runs. RF solid state 110 watts out. Wanting to know the pros or cons of running both antenna close together for more height with duplexer or spacing antennas for isolation without duplexer?
RE: [Repeater-Builder] Duplexer vs Split Level Antennas
I'll chime in. I would definitely mount the 2nd ant low enough below the 450 ft one to provide enough vertical separation to run without the duplexers. That way you always have the option. 60 plus feet on vhf. Somebody can run you the numbers if you provide station specs. It's a trade off. DB Loss of the stand alone ant receive path vs rx loss of a duplex antenna through the duplexer path. Not to mention the cost of the 2nd feedline and ant. I have a system on the air using the top ant for RX, works well. Don -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wb0goa Sent: Thursday, January 28, 2010 1:50 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Duplexer vs Split Level Antennas Have chance to install a DB 224 at 450' and another one anywhere below it. Using LDF6 on both runs. RF solid state 110 watts out. Wanting to know the pros or cons of running both antenna close together for more height with duplexer or spacing antennas for isolation without duplexer? Yahoo! Groups Links
Re: [Repeater-Builder] Duplexer vs Split Level Antennas
One of the best working repeaters I have run across was located on the outskirts of Ft Worth Texas on a 1000 ft tower. It used a single receive antenna at 1000 ft into a down converter that output on 10 meters. Several 10 meter receivers were connected to the RG-58 downlead in the radio room at the bottom of the tower. Each transmitter used a separate antenna at 500 ft and it was one of the best coverage repeaters for the flatlands that I have seen. I could reliably work it from 90 miles away with my mobile GE Prog. Vertical split antennas can work very well indeed. 73 - Jim W5ZIT --- On Thu, 1/28/10, wb0goa aero...@gmail.com wrote: From: wb0goa aero...@gmail.com Subject: [Repeater-Builder] Duplexer vs Split Level Antennas To: Repeater-Builder@yahoogroups.com Date: Thursday, January 28, 2010, 1:49 PM Have chance to install a DB 224 at 450' and another one anywhere below it. Using LDF6 on both runs. RF solid state 110 watts out. Wanting to know the pros or cons of running both antenna close together for more height with duplexer or spacing antennas for isolation without duplexer?
