GAM SS-2 Antenna Fails after 12 years

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
jimh
Posts: 6905
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

GAM SS-2 Antenna Fails after 12 years

Postby jimh » Fri Sep 13, 2019 10:33 am

During our cruise with the Great Lakes Boston Whaler Cruising Club in July 2019, I received a report that my radio was not transmitting at its usual strength. I also noticed it was not receiving very well. Diagnosis of the cause while on the cruise was difficult. The radio had just been changed for another transceiver, and I had not measured the power output or the receiver sensitivity of the newly installed radio. The new radio might have been the cause of the problems. I also was suspicious of a transmission line connector that I had somewhat hastily installed 12-years ago. After the cruise I replaced the connector, but the radio operation was still suspect. Upon closer examination, the problem was not in the radio, the connector, or the transmission line, but in the GAM ELECTRONICS SS-2 antenna itself.

The "closer inspection" I mention above was a closer visual inspection of the antenna. The antenna consists of two components: a metal whip, and a base transformer enclosure with a receptacle for the whip and a SO-239-type connector for the transmission line PL-259 connector. I discovered that there was a mechanical breakdown in the base transformer assembly. The top plastic insulation cap that seats onto the stainless steel tubular transformer coil enclosure had mechanically become loose. The cap is a press-fit onto the tubular transformer enclosure, and an adhesive is used to seal and retain it. After 13-seasons of use, the adhesive failed, and the cap vibrated loose from the transformer assembly. The soldered attachments of the transformer windings to the SO-239 connector were all that retained the cap and its attached whip to the transformer. With this mechanical strain, the solid wire conductors were subject to vibration movement and eventually failed.

Restoring the antenna to working condition required only replacing the transformer coil. The ADAP-II mount was still in good condition. A new transformer coil was obtained. The whip was removed from the old transformer and moved to the new transformer. The new transformer was threaded onto the ADAP-II mount. The total time to replace the antenna was about 90-seconds.

In my particular installation of this GAM SS-2 antenna and an ADAP-II mount, the antenna mast on which they are mounted spends about 97-percent of their life in a horizontal position. This means the weight of the whip is exerting a bending moment onto the plastic top cap of the transformer. Also, the boat is towed at highway speeds on the trailer with the antenna in this orientation, and there is a lot of oscillation of the whip in the air stream, exerting flexing onto the plastic cap. I believe that the almost constant horizontal orientation and the oscillating motion while the boat is towed on the trailer probably contributed to the mechanical failure of the joint between the transformer housing and the insulating plastic cap. In any case, almost 13-years of service is still an acceptable service life, and the replacement was very easily accomplished.

To get a replacement transformer assembly alone may be difficult, so the most expedient way to acquire a new one is to just order a new SS-2 antenna. This will provide a new transformer assembly and a new whip. The SS-2 is still available at a rather modest price from DEFENDER.COM at $55.

In some communication with GAM ELECTRONICS, I also learned that the former owner has retired and has sold GAM ELECTRONICS to a new firm, YANKEE MICROWAVE. The company continues to make the SS-2 and ADAP-II. They are now located in Maine and are no longer in New Hampshire. The antenna website continues to be

http://gamelectronicsinc.com/

The website also notes the antenna gain as 3-dBd (reference to a dipole) or 5.1-dBi (reference to isotropic). The ADAP-II mount has also been redesigned slightly.