[Elecraft] Auto Tuner Wish List

[Don]

Mike,

Trouble with that is you can't predict which of the 8 capacitors will be 
connected.  It may be the ones from only one side of the output bus.  My 
original breadboard, now scrapped, used just one relay per capacitor and I 
found that the circuit was badly out of balance when *no* capacitors were 
connected ... just the capacitance of the wires running to one side of all 
the capacitors was causing it.

The other reason I use two capacitors, one on each end of each capacitor, is 
that it puts two sets of relay contacts in series and so divides the voltage 
that each switch experiences.  I worry about voltage breakdown under high 
swr conditions when the voltage node occurs near the tuner and the two 
switches in series just doubles the ability of the tuner to survive that 
stress.

My antenna is a full wave horizontal loop for 160M which is a very forgiving 
antenna to match.  I feed it with ladder line and find that with all of that 
wire out there the voltages and currents do not seem to build up as badly as 
can happen with shorter antennas which are much more of a challenge for a 
tuner .. especially when operating at higher power.  What works for me may 
not work for others.

Don K7FJ



         < Don,
         < Rather that switching both sides of the caps, what about 
alternating which side they are connected to and which side is switched. 
That
         < should    keep things fairly well balanced and cut the relay 
count in half.
         < 73/72 - Mike WA8BXN


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