Scout Camp Repeater Project

by James Alderman, KF5WT

After two successful GOTA operations, and two Merit Badge classes, ham radio activity at the Clements Scout Ranch is about to expand even more!

Permanent HF Antenna

A club in Greenville, Texas has donated a Cushcraft R8 vertical antenna for permanent installation at the camp. This antenna will cover all bands from 6 to 40 meters, including the WARC bands.

The purpose of the antenna is to provide a permanent installation which makes ham activity more convenient. Either our club, or any club from Dallas, or any Scout leader attending the camp can set up a rig in a matter of minutes and conduct a class or GOTA activity.

The vertical will be installed on one of the up-croppings on the roof of the dining hall building. The feed line will run to an electrical box containing a coax switch located in the covered area of the dining hall.

One switch position will route signal to a wall-mounted coax connection inside the adjacent classroom. This is where classes are normally taught. The other position will route signal to a connection on the electrical box for setting up a station in the more open area of the dining hall.

The new permanent antenna will be a much better installation than the portable vertical which we have used in the past.

Merit Badge Classes

Within the next few days, at least one session of the Radio and Weather Merit Badges will be taught. These classes were extraordinarily successful during winter camp, with dozens of students being turned away because the classes filled so quickly.

This time around we will double class capacity. Even so, it’s expected that more Scouts will want to take Radio and Weather than we have spaces for. The club will continue to expand class opportunities by recruiting additional instructors. Our aim is to pass the excitement of Amateur Radio on to the next generation.

Scout Camp

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Camp Repeater

The Athens ARC is applying for a $1000 youth incentive grant from the ARRL. The broad purpose of the grant is to fund an “emergency communications and Amateur Radio training program” at the 3300 acre camp.

The 3000 word, 20-page grant application makes the case that present emergency communications capabilities at the camp are very limited. Cell phones don’t work there. Even 2-meter repeater coverage is spotty with an HT.

The proposal requests funding for a UHF ham repeater at the camp. The new repeater will be used for training and emergency purposes, and will serve as an additional courtesy and convenience to the thousands of Scouts and leasers who visit the camp each year, many of whom are hams.

As far as we know, Clements will be the first BSA camp in the nation with its own Amateur Radio repeater. No doubt it will generate great PR for the cause of Amateur Radio.

The total cost of the repeater is expected be in the neighborhood of $1300. However, some materials are even now being obtained from inexpensive surplus sources. A block diagram, technical description, and coverage plot of the repeater shown below.

If you have any of these materials lying around gathering dust, please consider donating them to the club for use in this project.

Appendix I – Technical Description

Antenna System: Two separate antennas will be utilized for transmit and receive, rather than a single antenna, to preclude the need for a costly duplexer and save over $1000. Two feed line runs of approximately 50 feet each will be of ½ inch diameter Heliax. Antennas will have of at least 6 dB gain. Each antenna will be located on top of a water storage tank at the camp’s pump station.

Controller: The controller will be an economical model NHRC-4 kit capable of operating the repeater as well as an optional link radio. (www.nhrc.net)

Physical Enclosure: The entire repeater will be enclosed in a weatherproof stainless steel electrical enclosure which will be mounted on a wooden pole. The enclosure is equipped with its own internal cooling fans.

Radio Units: Both the transmitter and receiver are Hamtronics kits. Both will be assembled and calibrated in a static safe, ISO-9000 certified radio shop in Dallas. The receiver will have a sensitivity of approximately .2 ¼V. The transmitter will put out approximately 2.5 watts to drive the PA, which will in turn put out approximately 12 watts into a 6 dB gain antenna for an ERP of over 40 watts.

Power Supply: The repeater will braw a maximum of 7 amps at 13.8 VDC. Batteries will provide backup power for several hours of operation. If AC power is lost, the PA will be disabled to switch the repeater to QRP mode. The power supply enclosure will also house the battery charger, AC/DC cut-over circuit, and a low voltage cut-off circuit.

Location: Latitude = 32° 05’ 07” North; Longitude = 95° 53’ 12 West; Elevation = 495’

Frequency: 441.725+ (100 Hertz sub-tone)

Repeater Block Diagram

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Repeater Coverage Map(Projected)

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Appendix II – Repeater Cost Breakdown

73, James Alderman, KF5WT