I used my Johnson Matchbox at our Field Day event about 3 years ago. I
went through each band and several frequencies on each band and compiled
a written chart identifying the settings for each band/frequency.
After 2 hours of trying to work stations on 20M, the radio failed and
they came to wake me from my late night nap. The result is the
Matchbox was adjusted for 80M in the CW portion and the operators were
complaining of high SWR and no power output on 20M. It took 2 hrs for
them to observe this? I was amazed at the number of "Extra Class"
operators at the site that thought the tuner was automatic and would
change with band / frequency changes on the radio. The radio by the way
WAS NOT an Elecraft product.
73
Bob, K4TAX
On 10/10/2019 7:35 PM, Don Wilhelm wrote:
Joe,
I agree completely, bring your Johnson Matchbox to the next Field Day!
Or even your old plug-in coil open frame link coupled balanced tuner.
Who has a link coupled tuner (like the Johnson Matchbox) these days?
Those are big boat anchor box these days (and hard to find). I have
one that sees little use, but I am not willing to part with it. It
does a good job when needed.
Most autotuners are of the L-network design and the manual tuners are
typically T-network - the L-network can be a high pass or a low pass
filter, but the more common T-network is always a high pass filter.
If one has an old Collins tuner, it may be a Pi-network which is a low
pass filter.
As you pointed out, the link coupled tuner is a bandpass filter, but
fixed tune bandpass filters will do just as well for multi-station
operation.
73,
Don W3FPR
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