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  • 30 Years Ago: How to switch high-voltage RF?

    From Paul W. Schleck@21:1/5 to It was on Sun Jun 20 14:31:42 2021
    XPost: rec.radio.amateur.moderated, rec.radio.amateur.homebrew

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    This is from a web-site that is replaying Usenet, and
    rec.radio.amateur.*, from 30 years ago (currently late spring/early
    summer 1991). The site is:

    http://www.olduse.net

    If you prefer to use your own newsreader, the site also supports an NNTP connection at:

    nntp.olduse.net:119


    From rec.radio.amateur.misc Sun Jun 20 17:51:05 2021
    Xref: utzoo sci.electronics:20315 rec.radio.amateur.misc:2773
    Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!ksr!jfw@ksr.com
    From: jfw@ksr.com (John F. Woods)
    Newsgroups: sci.electronics,rec.radio.amateur.misc
    Subject: How to switch high-voltage RF?
    Message-ID: <3636@ksr.com>
    Date: 20 May 91 14:11:24 GMT
    Sender: news@ksr.com
    Organization: Kendall Square Research Corp.
    Lines: 8

    Having recently seen an advertisement for a "smart" antenna tuner, I
    became curious about how they switch the inductances and capacitances
    in and out of the circuit. Since the smart tuner claims to be good
    for 300 watts, it would seem that they need switches that can
    withstand several hundred volts when open, but the case seemed a bit
    small for 11 high-voltage relays ("64 input capacitances, 32 output capacitances, and 256 values of inductance"; 11 binary switches).
    So, what are they likely to be using?


    From rec.radio.amateur.misc Tue May 25 12:43:16 2021
    Xref: utzoo rec.radio.amateur.misc:2804 sci.electronics:20328
    Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!lll-winken!aunro!ve6mgs!mark
    From: mark@ve6mgs.uucp (Mark Salyzyn)
    Newsgroups: rec.radio.amateur.misc,sci.electronics
    Subject: How to switch high-voltage RF?
    Message-ID: <1991May21.042050.5040@ve6mgs.uucp>
    Date: 20 May 91 14:11:24 GMT
    References: <3636@ksr.com>
    Sender: news@ksr.com
    Distribution: na
    Organization: Kendall Square Research Corp.
    Lines: 8

    In <3636@ksr.com> It was said:
    Having recently seen an advertisement for a "smart" antenna tuner, I
    became curious about how they switch the inductances and capacitances
    in and out of the circuit. Since the smart tuner claims to be good
    for 300 watts, it would seem that they need switches that can
    withstand several hundred volts when open, but the case seemed a bit
    small for 11 high-voltage relays ("64 input capacitances, 32 output >capacitances, and 256 values of inductance"; 11 binary switches).
    So, what are they likely to be using?
    I have the `smart' tuner in question. Regular relays (well, higher quality
    that Radio Shack) are used. No Gold or Silver contacts. No special
    precautions on the input side of the Pi tuning network. The middle `L'
    of the tuning circuit has the inductors shorted by the contacts, most are toriod, but all, I am sure, have no mutual inductance. The output caps, however, have TWO separate relays with their contacts in series. This is
    where the voltage can get rather high.

    Have Fun. 73 de VE6MGS/Mark -sk-


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