The question to be answered, is 0 maximum inductance or minimum inductance?
If it is minimum inductance then the position of C would be on the input
side of of 0 inductance or on the output side of 0 inductance. There would
be little to no apparent difference as a starting point. Therefore one can
not determine the best starting point for the Z siwtch position. Now if the
inductance is maximum value then it is very apparent where Z should be
located, either on the input of L or the output of L. I believe it general
practice to start with maximum inductance for adjustment of any L network.
I do not change the BYPASS switch with any power applied. My practice is to
set the tuner values using my analyzer and then record the values based on
frequency and band for future reference. Bottom line, I do not tune with
any power as it causes QRM on the band.
73
Bob, K4TAX
----- Original Message -----
From: "Marshall Stewart" <marsh@ka5m.net>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Saturday, July 27, 2013 9:49 AM
Subject: Re: [TenTec] TT 238C will not tune
I have a new T-T 238C impedance matching network. A gear reduction system
behind the front panel of the 238C is connected to a concentric skirt
turns
counter numbered 0 - 30 in a 180 degree arc over the top of the inductor
tuning knob. The operator's manual suggests that tuning start with the
inductor set fully counterclockwise at 0. It is okay to adjust the
capacitor
and inductor while transmitting with low power, 50W or less, but do not
turn
the rotary impedance switch with power applied. The length of the
transmission line, coax or Windowline, from the antenna feed point to the
tuner can make the difference between a load that can be matched and one
that is outside the range of the tuner.
73,
Marsh, KA5M
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