I happen to have been at both ends of that site, the 900' level and the cabinets on the ground.
As Jim says, this was in the early 70's. Configuration: 1000' tower with an inside "work" platform at 300, 600 and 900' (which were also the guy points - just 3 sets of guys! Yep, no elevator - manual climbing - ugh! A 3'x 3'x 1' weatherproof cabinet was installed on the 900' grating. Inside were two Janel receiving converters. The 2m one converted 146-148 MHz to 28-30 MHz. The UHF one converted 448-450 MHz to 30-32 MHz. Both fed RG-59 cables (that we unrolled from "backpacks" starting at the top while climbing down. Have you ever put a 1000' spool of RG-59 on your back and tried to climb down a tower? Ground equipment: In the outdoor racks back on the ground, power for both converters was fed up the RG-59. Testing prior to installation determined how much voltage to put in at the bottom to get the desired voltage at the top. The receivers were 30 MHz Mocom 10 units. To receive 146.340, the Mocom listened on 28.340. Back then the UHF repeater in town had a 200 KHz split - specifically so that our tube mobile radios could do repeat and simplex with F1/F2. So, for 448.900, another Mocom 10 was on 30.900 on the UHF converter. The 146.940 transmitter was a solid state 25w unit, built by one of the local broadcast engineers. It fed 7/8" Heliax to the 600' platform where another home built crappie pole hung off the tower. The isolation between the antennas was "measured" to be over 90 dB. As mentioned, in addition to the 16 and 34 receivers, a 94 receiver fed a 10w UHF transmitter on a yagi at about 50' to Harold's house. It was very easy to "cover" the local 94 repeater transmitter into this 94 receiver so we often got to listen in on simplex or distant repeater conversations on 94 even while the local repeater was in use. Repeating 94 to 94 was always one of those "tricks" for those that didn't know how the Starship worked. But that tower is no more... The TV station still exists and they built their current studios on the location. Mike / W5JR --- In [email protected], Jim Brown <w5...@...> wrote: > > 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...@...> wrote: > > From: allan crites <wa9...@...> > Subject: Re: [Repeater-Builder] Duplexer vs Split Level Antennas > To: [email protected] > 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 >
