[Johnson] 275 watt Matchbox Coil Setting

[pulsarxp at earthlink.net]

I have been using a Johnson Matchbox for years with 400 ohm ladder line.  I
have a 40 meter and a very long 80 meter inverted V up around 55 foot and
both of them are fed with the same 400 ohm ladder line.  I use this system
for MARS and go down about 200 khz below the 80 meter band and also up
around 500 Khz above the 75 meter band plus just above and below the 40
meter band.  The feedline is 100 foot long.  The matchbox nulls out the SWR
on all these frequencies.  I have tried 2 275 watt matchbox tuners and one
KW Johnson Matchbox.  They all work equally as well as the others and I get
great signal reports with them.  

The other day I hooked up a Nye Viking MB-V-A tuner to the same antenna
system.  I got exactly the same reports using either type tuner. 
 I had suspected the MB-V-A  would not do as well because of the internal
balun when using open wire line.  This turned out not to be the case at
all. It performed just as well as the Johnson tuners and frankly was easier
to tune due to its reduction drive and built in automatic SWR/Power  meter.
I went back and forth between the different brands of tuners and even
though the circuits were entirely different,  I got the same great reports
with any of them.  I have always felt the need to stay away from a balun
within a tuner but this test has changed my view of all this.  At least in
my case, a balun within the tuner did not degrade my antenna's performance.
Lee
w0vt
AFA4CM





> Subject: RE: [Johnson] 275 watt Matchbox Coil Setting
>
> Congratulations. I am afraid you may have discovered the dirty little
secret 
> of the Matchboxes. They will not handle very large impedance excursions.