The antenna tuner hybrid A1 pulses
101 - KL3 is in, KL2 is out, KL1
the set driver transistor with
The L-C clock determines
the count timebase.
The output of the set driver tran-
The count continues until the Z
sistor changes from +16v to
drops to indicate 100 ohms or
At that time, the Z compar-
ator digital output changes state
The relay closes and short cir-
and signals the control logic.
cuits the inductive element (a
coil) connected in parallel.
The control logic places capaci-
tors KC1-KC8 between the rf path
To switch an inductive element into
and ground in a binary count.
the rf pathway, the reset driver must be
hybrid samples the vswr voltage
The capacitive element
and compares it to a reference at
(KC1-KC8) is connected in series with
When the reset driver is
pulsed, the relay opens and switches the
Capacitance is incrementally added
element out of the rf pathway.
until the vswr reaches 1.5:1.
set driver is pulsed, the relay closes
comparator changes state and sig-
and switches the element into the rf
nals the control logic.
1.5:1 vswr is not reached when all
the capacitors are added, they are
reset. Another inductor is added
consists of the following:
and the capacitor count begins
When the Keyline is grounded after
a Tune Start or Tune Check Enable
When the vswr is 1.5:1, satisfac-
has occurred, a Tune In Progress
tory impedance match has been
signal (active state is +0.7v or
The control logic dis-
less) is routed to the power
continues the ground on the Tune
amplifier and the transfer relay.
In Progress line.
relay is deenergized and the rf
This causes +16v regulated to be
applied to the relays KL1-KL11 and
sensor bridge (R6-25, T2) ceases
to sample the rf.
KC1-KC8, and the rf is routed
voltage to the relays KL1-KL11,
through the energized contacts of
transfer relay to the rf sensor
KC1-KC8 is removed.
bridge (R6-25, T2). The rf sensor
are held in place by magnetic
bridge outputs Z (impedance),
vswr, and ALC analog voltages.
Frequency Select Logic.
The antenna tuner hybrid A1 places
Frequency Select Logic signals from the
control panel are applied to the control
the inductors KL1-KL11 in a binary
logic in the antenna tuner hybrid.
count in the rf path by opening
control logic selects which inductors
the associated relay.
and capacitors will be used at a parti-
samples the analog Z voltage and
cular frequency band.
This is shown in
compares the Z voltage to a refer-
For example, at 2,000 kHz,
ence at a comparator.
inductors KL1, KL2, and KL3 are bypassed
in the binary count.
KL4 becomes the
The inductance is incrementally
least significant bit.
added in a binary count.
inductance of KL2 is twice KL1;
KL3 is twice KL2; KL4 is twice
The average tuning time is
approximately 3 seconds, but may run as
(For example, on the
fifth binary count - binary number
long as 12 seconds. If the tuning has