You don't see an antenna tuner made like this everyday

Discussion in 'Homebrew and Kit Projects' started by KD8UYQ, Jun 29, 2017.

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  1. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello all,

    All most every week it is like Christmas at the Museum of Radio and Technology. I volunteer there two to three days a week giving tours, doing maintenance work, and whatever else needs to be done.

    This piece of homebrew art came to us from a daughter of a SK.




    We can't tell for sure but we think these two variable condensers were made by the builder.


    This antenna tuner, and some tube based liner amplifiers that he also built came to us back in February but we just now got around to deciding what to do with his treasures. I was asked to clean this piece up because I believe it will be going into the ham radio section at the museum. The well crafted linear amps that he made will most likely be sold at our auction in July.

    AF6LJ and KB4QAA like this.
  2. KL7AJ

    KL7AJ Premium Subscriber QRZ Page

    Link coupled tuner.....a Matchbox on steroids.
    AF6LJ likes this.
  3. RICHS

    RICHS QRZ Member

    "You don't see an antenna tuner made like this everyday"

    That's good you don't. These old ball buster massive tuners don't work at 20 meters or higher and if they do they have very poor matching range on all the HF bands especially on the lower frequencies. I'll take a small compact tuner with vacuum caps and reasonable size inductors. These tuners have very wide matching range and high power capability too. Sometimes huge isn't better.
  4. KG7SWP

    KG7SWP Ham Member QRZ Page

    To me, 20 meters & up would not be important. They can be covered with a simple & relatively small fan/parallel dipole. It's 80 & 160 that really need a heavy duty tuner for covering the band. Heck, 40 can usually be covered with a single dipole.

    K8AI and AI3V like this.
  5. N5DMC

    N5DMC Ham Member QRZ Page

    Those are my kind of knobs, what kind are they, resistance test set? Simpson maybe?
    AF6LJ likes this.
  6. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    Oh I don't know..
    My KW matchbox works fine on ten, fifteen, and twenty.
    KD9CKB likes this.
  7. RICHS

    RICHS QRZ Member

    Take a hard look at the caps in the above tuner. I will bet their minimum capacitance is so much higher than the Johnson's in your tuner, the above tuner would not work as well as a Johnson. On the other hand, a well designed T network will have a much wider matching range than a Johnson tuner if for no other reason Johnson's method to vary the coupling between tuner and load is very limited. Those differential caps don't work as well as double L networks in a T network. Every tuner design has advantages and disadvantages compared to other tuner designs. It's everybody's choice to choose what they want.
  8. N2EY

    N2EY Ham Member QRZ Page

    N2SR likes this.
  9. N2EY

    N2EY Ham Member QRZ Page

    No, it's a homebrew copy of an EFJ KW Matchbox.
    N2SR likes this.
  10. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hi Doug,

    I don't the origin of those knobs but we have a box filled with all sorts of vintage knobs like that.

    As far as how well this home made Matchbox works That is unknown. It has switch and tuning range marking for 80 through 10 meters and as far as we know it was used regularly.


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