On 4/25/2012 4:09 PM, Alan Bloom wrote: > P.S. Sorry, I guess I violated the Usenet rule against posting objective > data...
It should be noted that in an earlier post, I noted that I had measured the loss of 1300 ft of coax with characteristics like LMR400 that had been cut into 100 ft and 200 ft lengths for a DX trip. I noted that there were at least 25 PL259s and 13 Amphenol barrels in line, and that the loss at every frequency up to 500 MHz was less than the mfr's spec for the cable at that frequency. While I did not go to the extent of finding and measuring 1,300 ft of the same coax and subtracting out the loss, I submit that my measurements show that the loss in those 38 connectors is negligible to at least 500 MHz. And I also submit that not every small deviation from the ideal MATTERS in every real world conditions. Good engineering is making good choices for a given situation. The world does not need the $800 hammers demanded by certain military specs. Shouting down? Hardly -- when completely illogical arguments were presented as justification for a position I pointed them out. Also -- I don't trust the precision of loss measurements for very small losses -- there are two many factors that can pollute the measurement, and often the accuracy of the instrumentation is a significant.fraction of the result being measured. For example, try getting a good number for the loss of 100 ft of LMR400 at 1.8 MHz. You'd better be measuring at least 1,000 ft to get even 10% accuracy! Several years ago, a VE1 (RGB, I think) sent me data for measurements he had made of a sizable number of UHF connectors in a string. His numbers for loss in a single connector were significantly less than what Alan has posted. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
