Temperature Compensation ICOMs and TCXOs

Posted on Feb 7, 2014

This page deals with the subject of replacing the crystal in any type of Temperature Compensated Crystal Oscillator (TCXO), be it a Motorola `Channel Element`, a GE `Integrated Circuit Oscillator Module` (commonly called an ICOM), or an RCA TCXO. Here we`re going to use the term `element` just to make writing this article easier.

Temperature Compensation ICOMs and TCXOs
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We`re going to describe the problems that can arise by rebuilding them yourself. Most hams are frugal (some are downright cheap) by nature, always wanting to save a nickel anywhere they can. Replacing the crystal in the precision frequency determining element is a necessary task when taking a crystal controlled radio and moving it from one frequency to another. Money can be saved by recrystaling the elements yourself, but there are problems that can arise when doing so. Many folks don`t know about the issues when buying a $10-$15 crystal and stuffing it into the element themselves. Sometimes the issues are with the crystal itself, sometimes they are with the element, and lastly, both can contribute to the end result. One comment I have heard over and over again - places like Sentry and International do not just recrystal an element, they remanufacture it. Unfortunately, the crystal houses and several manufacturers manuals refer to the remanufacturing process as "compensating" the element despite the fact that temperature compensation is only one factor in the remanufacturing process. . There still seems to be a tendency to seize upon temperature compensation as the primary reason for sending the element to a crystal house, and that is not the case. In fact, the temperature compensation is not the most important issue at hand. Transmit elements: Some element designs have the modulator inside, some do not. On those that do,...

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