Ed-
I did find one website touting the Annecke tuner and suggesting a mod for
the Matchbox that I might try.
It involves adding a 4 position switch and using it to tap the link coil in
several places, along with a 270 pf variable cap in series with the input.
I have long since gotten my money's worth out of the MB so not afraid to
drill a couple extra holes in the front panel.
I would love to hear from anybody on TT (or elsewhere) that has tried this.
Re the TenTec 238, I have one of those also. It's been a good tuner up
until ARRL DX CW a few weeks ago.
I hooked it up to a 75 meter dipole fed with about 70' of 450 ohm line.
Worked OK for a while until I hit it with a KW. The SWR meter indicated an
arc or flashover, but didn't see anything obvious upon removing the cover
and inspecting. My money is on that it's the balun.
73
Tom
K0SN
On Mon, Mar 14, 2022 at 8:49 AM Edward Mccann via TowerTalk <
towertalk@contesting.com> wrote:
> Interesting trip down memory lane re EFJ.
>
> Internet posts elsewhere show back in the day then-available Annecke
> tuners best the Matchbox; various mods suggested. Unfortunately,
> suggestions present minimal proof of results, however, probably due to
> determining “performance” actually dependent on the aerial used and
> environment.
>
> It seems the manufacturing rage that followed in the search for tuners
> offering solutions for “balanced”
> antennas led OEMs to inclusion of baluns in the output circuit. Most of
> them appear to be voltage baluns as opposed to 1:1 current baluns,
> apparently chasing the notion that a 4:1 transformation at the back of the
> box made an efficient hook-up to twinlead or ladder line at the shack wall,
> without consideration of Z shack not necessarily Zo.
>
> Another website has recently tried ti evaluate the balun of the
> then-popular Heathkit 2040/2060 series, with the observation they used a
> ferrite transformer design.
>
> Does anyone have any accurate observations on the characterization of Ten
> Tec 228/229 tuner baluns? Would be interesting to know.
>
> Best from the West,
>
> Ed McCann
> AG6CX
>
>
> Sent from my iPhone
>
> > On Mar 14, 2022, at 4:13 AM, Rob Atkinson <ranchorobbo@gmail.com> wrote:
> >
> > The "link" (that's the larger outer coil) originally had two taps.
> > One just one or two turns from the grounded end. That was the 50 ohm
> > unbalanced input. A second tap was a few turns over from that. It
> > was for 300 ohm receiving line. A lot of receivers had terminal
> > strips on their back panels for the option of 300 ohm twin lead
> > balance line for receiving, in the 1950s and '60s. A Matchbox that
> > doesn't have the link has been extremely modified into something else.
> > It can no longer be a link coupled balanced line network. Which
> > brings me to a question: Are you using your Matchbox for coax, or
> > ladder line to your antenna?
> >
> > I have one in regular use here with ladder line and a dipole. It will
> > be easier to determine what's going on with it if you get it out of
> > its cover and run it in the open so you can see what's going on WRT
> > capacitor meshing. Just unscrew the zillion screws and put the knobs
> > back on and connect the feedlines back up and you'll be able to see if
> > you are running out of capacitance, or don't have enough etc.
> >
> > 73
> > Rob
> > K5UJ
> > _______________________________________________
> >
> >
> >
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