Greetings All: While reviewing the text of CTR 38, I noticed that the range of feed resistances called out for the tests has been reduced from what is called out in CTR 21. In CTR 21, the range is 230 ohms to 3200 ohms, while in CTR 38 the range is 500 ohms to 2800 ohms.
I am particularly interested in the reasoning behind the change in the lower end of the range, from the 230 ohm value in CTR 21 to the 500 ohm value in CTR 38. As we have discussed in this forum in the past, many people feel that the 230 ohm condition in CTR 21 is unreasonable and perhaps outdated. This condition results in about 2 watts being dissipated in the TE, which is difficult to contend with in space-constrained TE devices. With the 500 ohm lower limit in CTR 38, the maximum dissipation in the TE is reduced to about 1.2 watts. This is still high, but it is much more manageable that 2 watts. My question is whether the 500 ohm value in CTR 38 represents an updated view among those who develop the requirements, and if so, is there any chance that CTR 21 will be revised to use this value as well? If any of you have insight on this issue, your comments would be appreciated. Joe Randolph Randolph Telecom, Inc.
