NEWS
NEW REPEATER AT W5PDO - THE END OF AN ERA
by Alden Oyer, AG5S
April 11, 2001 (Los Alamos, NM) - What might be the longest-running repeater chassis in the world was retired on Wednesday when the 146.88 vacuum tube repeater was replaced with a new solid state version. The original repeater was placed in service at its present location in the base of the "white golfball on at Tee" water tower on Baranca Mesa on October 18, 1968. It has remained on the air continuously since then except for short intervals when power service was interrupted or the machine was down for repair. The transmitter and receiver were a Motorola Mobile 80D, modified for fixed service by replacing the dynamotors with a power supply fed from the commercial mains. The RTL controller was home brewed by the club. The Morse ID was generated electro-optically by shining a light onto a photocell through a rotating, perforated disk. Although many tubes were replaced over the years, the Morse ID light is the original bulb, having never burned out.
In the past year or so, age was beginning to take its toll. In addition to occasional tube replacements, passive components including resistors, capacitors and transformers were failing with increasing frequency. Bob Cowan, K5QIN, acquired and assembled the components for the new solid-state repeater - a transmitter strip from a Motorola Motran, a receiver strip from a GE MASTR, and an NHRC-2 controller. Bob has programmed a short squelch tail and no courtesy beep, and has added an audio delay circuit to eliminate squelch pop. The repeater uses the same home-built duplexer of the old repeater, a 4-cavity hybrid ring. Some work still need to be performed to lessen the 6 db loss through the duplexer, and the antenna, several hundred feet up on top of the water tower, needs to be checked. Any volunteers for the latter task (or should I say ladder task)?
The simplex autopatch, previously on 147.99 MHz, has QSYed to the repeater. To access this open autopatch, identify yourself, send *88, and release the PTT. Wait for the dialtone to disappear and then enter your number. Remember, this is a simplex autopatch. Only one person talks at a time. When you are finished, press # to hang up. A rapid Morse ID will indicate success.
Please use the repeater and let us know its coverage and how it performs. You can e-mail comments directly to K5QIN or the webmaster.
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Last updated Saturday, April 14, 2001