On 2/17/2019 6:26 PM, Randy Farmer wrote:
I concur with the comments on the Top Ten 2-way switches. I'm using about 10 of them at various places in my SO2R contest station antenna and BPF switching networks. They work well and have good isolation. I
On the basis of my measurements with a Vector Network Analyzer, I am NOT impressed with these switches, and consider them poorly designed. The major design flaw is that they depend upon the chassis for signal return, so the signal path gets increasingly badly mismatched at 15M and above. I didn't measure crosstalk, but this design error would certainly impact it. I reduced the mismatch by about half by adding braid from the coax connectors to the circuit board and following (as best I could) the signal path to provide a return. Why? Because the "ground" layer is broken under the top layer, so it can't act as a return either!
Someone cited 50 dB as "good isolation." When I replaced my WX0B 6x2, I measured isolation of about 55 dB. The replacement, a 4O3A 6x2, measured 75 dB worst case. And other one I'm using now, the 4O3A Antenna Genius, measures better than 95 dB worst case.
If you look inside a well designed power amp, you'll see transmission line running from input and output for both TX and RX path. My Ten Tec Titans were built that way, and so is the KPA500. You'll also see mini-coax jumpers tying sections of the K3 together.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
