Timing is everything! But Ironic.
Maybe worth while and informative to the group to perform an autopsy with
pictures of the balun. Would reveal windings, current or voltage, etc.
A non-human sacrifice.
73
Ed
AG6CX
Sent from my iPhone
> On Mar 14, 2022, at 8:19 AM, Tom Hellem <tom.hellem@gmail.com> wrote:
>
> 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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