The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. However, you are correct that it will not serve as a common mode choke with unbalanced output. And Paul's comments about the placement of the balun are correct. I was surprised to see this from Alpha, whom I would have expected to know better.
I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or hinted at as far as I know!) On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote: > >> The new RF Concepts tuner would not work well for me. It's an >> unbalanced C-L-C design with a CM choke input, similar in design >> with several Palstar tuners, only with much more rugged components >> than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a >> current choke placed at the input to a C-L-C tuner and have concluded >> that placement at the input is not as effective for maintaining line >> balance as a balun placed at the tuner's output. > The common mode choke in the Alpha tuner will be completely ineffective > with any of the coaxial fed antenna outputs in any case! Since it is > *inside* a metal box and the input as well as output connectors are all > connected to the case, any common mode current will simply bypass the > the choke on the case! > > The *only way* to make a common mode choke effective with an unbalanced > tuner is to connect the case of the tuner to a low impedance "ground" > and place the choke in the feedline between the rig/amplifier and the > tuner - external to the tuner. > > 73, > > ... Joe, W4TV > > -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ 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
