QST via Paul Grigorieff, PIO / Half Moon Bay ARC
[email protected]
March 8, 2021
SAN MATEO COASTSIDE HOLDS 37-STATION SIMPLEX TEST
On Saturday, February 20th , the Half Moon Bay ARC and the Coastside CERT organization (sponsored by the Coastside Fire Protection District), conducted a very successful test of 2 meter simplex (point-to-point) communication along a 10-mile stretch of the northern San Mateo County coast (which extends from south Half Moon Bay to Moss Beach). The number of stations participating in this drill (37) roughly doubled from last year, and the average of all Circuit Merit readings reported by our participants also increased by about 25%, from 2.3 to 2.9.
Simplex networks like ours are an important part of ham radio emergency communication, since they prepare us for emergencies during which local repeaters are disabled by heavy winds or rains, or by earthquakes. Drills like ours also get new hams accustomed to using simplex frequencies, which are known as tactical channels under our coordinated Coastside Band Plan, and demonstrate that even small handhelds (when equipped with whip antennas) can reach out for quite a distance.
About half of this year’s participating stations employed external antennas, and more than half of these were J-Poles. After conducting last year’s simplex test, we made a Club purchase of the OSJ 146/440 J-Pole from Arrow Antenna [arrowantennas.com], and found that subsequent installation of these antennas greatly increased our Coastside connectivity and signal strength. Based on this year’s results, we intend to repeat this strategy for the benefit of our rapidly growing group of new hams.
However, like many California coastal areas, the north San Mateo County coastside has many ridges and canyons, which, no matter what type of antenna is used, give rise to significant “dead spots” for 2 meter simplex transmission and reception. The resulting Circuit Merit 0 reports in our drill significantly reduced the average of reported signal levels for our 37-station group. We also found that the stations within these “dead zones” also logged significantly lower Circuit Merit reports for other nearby stations that were also within the zones.
One strategy that seemed effective in dealing with these “dead zones” was dispatching a mobile station with a strong (20w-50w) transceiver up to a high point along one of our ridgelines. Such a station succeeded during the drill in pulling out many otherwise inaudible signals. This has caused the Club to consider dispatching such a “highpoint relay” station to function during emergencies, and to consider putting together a temporary, mobile repeater which could be located on one of our ridgelines during emergencies.
With their kind permission, during the test we made use of the CARLA-32 repeater, which is maintained by the California Amateur Radio Linking Association atop nearby Montara Mountain. [CARLA’s website can be found at www.carlaradio.net.] We used the repeater to call the roll of participating stations,one at a time. Then each station made a simplex transmission on 147.555 MHz which all participants evaluated and reported on. These reports were arrayed in a large to/from Excel spreadsheet, in which was painstakingly assembled by Lee Copeland, our Emergency Coordinator. Anyone wishing a copy of the script we used for the drill is welcome to email Paul Grigorieff, [email protected].
