[AMRadio] Balanced tuner

[Mark Foltarz]

I did add the series capacitor and also added the tap switch for the primary  of the coupling inductor.The plate spacing of the added series capacitor  happens to be  smaller than the original capacitor there.
I use the tuner regularly with the T-368 without any arcing.
The primary tap switch is old surplus, the type used in the  BC375 tuners.
I used #14 solid copper wire to wire up the taps.

de ka4jvyMark


      From: Mike Sawyer <w3slk at verizon.net>
 To: 'Mark Foltarz' <Foltarz at rocketmail.com>; amradio at mailman.qth.net 
 Sent: Saturday, April 28, 2018 8:16 AM
 Subject: RE: [AMRadio] Balanced tuner
   
Nice website Mark,
    I went and book-marked it. DJ0IJ is very articulate in his reasons and methods. I'm going to be reading over some of the remainder of his site to glean any other useful information. With regards to the 'Matchbox', he advocates adding a 3rd capacitor in series on the input side of the 'box'. One has to be reminded that capacitor needs to be as large, (voltage wise) as the final's 'tune' on any 'boat-anchor' or amplifier! Component selection must be made accordingly. Remember the original Johnson KW Matchbox was designed at the time for a 1KW input. The closer you are to a match on the frequency of selection, the lesser your chance of 'fireworks!'
    Of course, your mileage may vary!

Mod-U-Lator,
Mike(y)/W3SLK



-----Original Message-----
From: amradio-bounces at mailman.qth.net [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Mark Foltarz via AMRadio
Sent: Friday, April 27, 2018 11:36 PM
To: CL in NC; amradio at mailman.qth.net
Subject: Re: [AMRadio] Balanced tuner

Charlie,
  I have a Johnson KW matchbox that I picked up years ago.When I got it it was a junker. Lots of extra holes and  the cabinet was ugly.
I believe it was used for a magazine article some years back where the tuner had 160 meters added.
I also had trouble matching  various dipoles with it. Some worked great while others would not.
I found this link http://www.dj0ip.de/antenna-matchboxes/symmetrical-matchboxes/j-viking-upgrade-1/
Since the match box was sort of ugly  to begin with I took the plunge and did the mods.
Wow, the improvement is significant. The tuner actually works well now. As well as any balanced tuner I have seen -including my TMC TAC-1,
Just  a thought 
de KA4JVY
Mark