That switch is rated at 2500W PEP but only 1000W CW. Has anyone used them at 1500W CW or RTTY?
73, Jim N7US -----Original Message----- Let's add some real numbers. I have a mechanical A/B switch DIAWA Model CS-201. Fairly inexpensive. Internally, it has a cavity design to provide isolation between the ports. Using an HP signal generator and an HP-3586C selective level meter the isolation of the switch was measured. The used port was terminated in a 50 ohm dummy load. The "open" port went into the selective level meter which had a input Z of 50 ohms. The HP-3586C can measure RF power levels accurately within a few tenths of a dBm. Differences are at least as accurate. Here are some numbers: 160M/80M 80 dB isolation 20M 69 dB isolation 10M 60 dB isolation 6M (by extrapolation) 46 dB. YMMV Note the frequency dependence. This switch provides the 40 dB isolation necessary. I have no connection with DIAWA but was interested in this topic. I suspect there is some real junk out there. Obtaining 60+ dB isolation isn't easy. The slide switch "designs" described by some are likely in that junk category. If in doubt measure. You have two rigs and an S meter. Input .1 or 1 watt to the switch terminated as above and look at the S meter for the rig on the open port. Scale the results to 100 W. If it shows S9+80 dB or less, you are likely OK. Keep in mind many S meters are horribly inaccurate. They tend to be too generous at around S9. Not knowing could be expensive. 73 de Brian/K3KO ______________________________________________________________ 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 Message delivered to [email protected]
