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TM
11-5820-919-40-1
The  antenna  tuner  hybrid  A1  pulses
101 - KL3 is in, KL2 is out, KL1
1.
the  set  driver  transistor  with
is in.)
The  L-C  clock  determines
+0.8v.
the  count  timebase.
2.
The output of the set driver tran-
4.
The  count  continues  until  the  Z
sistor  changes  from  +16v  to
drops to indicate 100 ohms or
ground.
less.
At that time, the Z compar-
ator  digital  output  changes  state
The  relay  closes  and  short  cir-
3.
and  signals  the  control  logic.
cuits  the  inductive  element  (a
coil)  connected  in  parallel.
5.
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
the rf pathway,  the reset driver must be
hybrid  samples  the  vswr  voltage
The  capacitive  element
pulsed.
and compares it to a reference at
(KC1-KC8)  is  connected  in  series  with
a
the relay.
When the reset driver is
pulsed,  the  relay  opens  and  switches  the
Capacitance  is  incrementally  added
6.
When  the
element out of the rf pathway.
The
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.
If the
pathway.
1.5:1 vswr is not reached when all
the  capacitors  are  added,  they  are
The
tuning
cycle
Tuning  Cycle.
reset.  Another  inductor  is  added
consists  of  the  following:
and  the  capacitor  count  begins
again.
1.
When  the  Keyline  is  grounded  after
a Tune Start or Tune Check Enable
When  the  vswr  is  1.5:1,  satisfac-
7.
has  occurred,  a Tune In Progress
tory  impedance  match  has  been
signal  (active  state  is  +0.7v  or
achieved.
The  control  logic  dis-
less) is routed to the power
continues  the  ground  on  the  Tune
The  transfer
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
The  supply
voltage  to  the  relays  KL1-KL11,
through  the  energized  contacts  of
transfer  relay  to  the  rf  sensor
KC1-KC8  is  removed.
The  relays
bridge  (R6-25,  T2).  The  rf  sensor
are held in place by magnetic
latching.
bridge  outputs  Z  (impedance),
vswr,  and  ALC  analog  voltages.
The
Frequency Select  Logic.
The  antenna  tuner  hybrid  A1  places
Frequency  Select  Logic  signals  from  the
2.
control  panel  are  applied  to  the  control
the  inductors  KL1-KL11  in  a  binary
The
logic  in  the  antenna  tuner  hybrid.
count in the rf path by opening
control  logic  selects  which  inductors
The  hybrid
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
3.
least  significant  bit.
The
added in a binary count.
inductance of KL2 is twice KL1;
2-131.
KL3 is twice KL2; KL4 is twice
The  average  tuning  time  is
approximately  3  seconds,  but  may  run  as
KL3,  etc.
(For example, on the
fifth  binary  count  -  binary  number
long  as  12  seconds.  If  the  tuning  has


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