Taps For A Toggle Switch

Discussion in 'Ham Radio Discussions' started by N2EY, Jul 4, 2021.

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  1. N2EY

    N2EY XML Subscriber QRZ Page

    The oldest part of the Southgate Type 7 transceiver is a simple 4 x 4 x 2 inch utility box.

    This box dates back to the late 1970s, and contains two toggle switches and a couple of connectors.

    One toggle switch turns the transmitter power supply on and off, and the other controls transmit and receive. (It was done this way so that the transmitter power supply could be located out of reach from the operating position, yet be easily controlled.)

    This little box was used with the Southgate Type 5 and Type 6, long before the Type 7.

    After 40ish years of service, the TR toggle switch failed right in the middle of a CWT session. Not a problem - the box was unplugged, dismounted, a new switch taken from the spares stock while the soldering iron was heating, and the switches swapped. As soon as the solder cooled the box was replaced and back on the air. 27 minutes start to finish.

    The removed switch wasn't new when the box was first built. Who knows how many thousands of Qs it participated in over the decades?

    I think it earned its rest.

    Ironically, after a few hours of use, the replacement switch didn't "feel right", so the spares stock was gone through carefully to find a switch with the right "feel", and a second swap made. That switch already has a few hundred Qs to its credit.

    73 de Jim, N2EY
  2. N2EY

    N2EY XML Subscriber QRZ Page


    The control box with new toggle switch (top) installed.
    N0TZU, G3EDM and AD5HR like this.
  3. G3EDM

    G3EDM Ham Member QRZ Page

    My T/R switch:



    The toggle switch, fronted by a National metal knob, is a cheap modern-day wafer switch. I suspect it will last a lot less time than Jim's switch. One wafer switches the antenna. Also, in the receive position, a 15W resistive dummy load (the gold coloured component) is put across the TX antenna output. Another wafer mutes the receiver on transmit (when you close the contact, it actuates a reed relay inside the receiver).

    The capacitor is an "antenna tune" control active only in the receive position (it is switchable using the black slider switch underneath). The potentiometer, also only active on receive, is an attenuator on the antenna, to prevent overloading of the regenerative receiver with strong signals.


    I bolted a lead weight to the bottom plate to prevent this small unit from sliding around the desk:


    One of my next projects is an extension cord for the headphones so that it doesn't get tangled with the keying position. I will probably bolt a minibox to the underside/front of the desk with a new headphone socket (vintage "tip jacks").

    Will possibly include an output transformer and second socket so that modern low-impedance 'phones can be used; they are much more comfortable than the vintage high-impedance cans you see in the photo!

    This was my spacious shack in America. In my new, much smaller QTH in southern England, the only units at table-level will be the receiver and T/R switch with any other equipment arranged vertically above the much smaller desk.


    It is all very basic, but it works. Among other things, that Novice transmitter includes a two-transistor sidetone oscillator. The headphone output from the receiver (the two white jacks) is wired to the transmitter's sidetone circuit, and the headphones are plugged into the sidetone output on the right hand side of the transmitter. On receive, it operates as a straight-through circuit.


    73 de Martin, G3EDM
    Last edited: Jul 4, 2021
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  4. N2EY

    N2EY XML Subscriber QRZ Page

    Note the metal bracket on the left. It secures the small box to the shelf support so that it can't move. @G3EDM's weight idea would work as well, but the bracket was handy when the station was built.

    The TR switch box is the only assembly in the Type 7 that is fastened to the desk.

    73 de Jim, N2EY
  5. W7HV

    W7HV Ham Member QRZ Page

    Good ol' toggle switches; robust, bold, in-your-face, highly tactile. Rockers, pushbuttons and touch screens are what we get now.
  6. WA1GXC

    WA1GXC Ham Member QRZ Page

    I am always nostalgic for the names of the Grand Old Manufacturers, many of whom are now gone but many of us recognize and
    fondly and sadly accompany us as we speed to the edge of the Universe.

    Looks like it was a standard Cutler-Hammer or an Arrow, Hart & Hageman. Which?


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