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Standard Communications Corp.

Element type : Dynamic

Before installing this microphone for portable use in my amateur transceiver, I decided to check the wiring assembly by dismantling its shell to record the factory configuration. Interestingly, I found two unique features of this microphone. They are:

1. There is a rubber spacer between the microphone element and the solid metal cylinder. Afterassembly, these parts are held tight by the mounting screws. This design is probably to hold tight the mic element assembly to prevent clatter when jarred during use. Or, perhaps the metal cylinder functions as an anti-resonant/resonant device (or asks the manufacturer!)
2. There is a resistor that is electrically connected to the hang mount. This feature is common to communications equipment that incorporate a tone squelch system. When the microphone is returned to its hang mount (normally installed at the side of the transceiver’s case - grounded), the tone squelch system will mute the receive audio. When a set tone is received, the radio will wake up, the receiving operator will pickup the mic from its mount and communiocation between the caller and receiver is established. When the mic is retuned to its mount, the radio will return to mute condition. Hence, the radio will remain silent until a tone recognized by the radio’s tone squelch system is received.

The audio quality of this microphone is good and its spectrum is typical to the required bandwidth for telecommunication purposes.

This microphone apparently was intended to be used for commercial and private communication transceivers.

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Before indulging directly in the design of VHF colinear antennas, it is worthwhile to review our antenna theory and practice of antenna home brewing. The basic principles presented in this article are standard techniques used by the radio industry to come up with finished products for commercial purposes. There is no doubt that the home brewer can similarly construct his own antenna, resulting in a finished product of equal or even better performance than the commercial ones. The beauty of home brewing is clear. It gives complete satisfaction to the builder that leads him to that great feeling of “ownership”. Some general principles of the design of colinear antennas, matching and feeding techniques are presented. These principles and techniques however can be applied to other antenna projects in mind. Actual construction techniques are left to the home brewer to use his own skills and aesthetic tendencies to produce his finished project. As long as the design and electrical characteristics are met, the finished product will perform work efficiently to provide years of service.