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I MODEL
4OO TRANSCEIVER
B.
Installation
(Cont)
seLector s\ritch
should be installed
to
s e l e c t e i t h e r t h e b r o a d c a s t r e c e i v e r o r
tranaceiver
output.
MICROPHONE
The rnicrophone
input is designed lor
high impedance rnicrophones
only.
The
c h o i c e o I m i c r o p h o n e i s i m p o r l a n t ,
f o r
good speech quality,
and ehould be given
s e r i o u s c o n s i d e r a t i o n .
T h € c r y s t a l
lattice
filter
in the transceive!
provides
a l l t h e r e s t r i c t i o n n e c e s s a r y o n a u d i o
response,
and fr.rrther restriction
in the
m i c r o p h o n e i s n o t r e q u i r e d .
l t i s m o r e
irnportant
to have a mic rophone with a
smooth,
flat response throughout
the
speech range.
The microPhone
PIug
s h o u l d b e a s t a n d a r d l / 4 i n . d i a m e t e !
t h r e e - c o n t a c t t y p e .
T h e t i P c o n n e c t i o n
i s f o r p u s h - t o - t a l k
r e l a y c o n t r o l , t h e
r i n g c o n n e c t o r i s f o r t h e m i c r o p h o n e
terminal,
and the sleeve is for the com-
r n o n c h a s s i s g r o u n d .
T h e m a n u f a c t u ! e l i s
instructions
should be followed in connect-
ing the lnicrophone
cable to the Plug.
W i t h m a n y m i c r o p h o n e 6 , t h e p u s h - t o - t a l k
button rnust be pressed to make the
rnicrophone
operative,
even though the
panel function switch i5 in the transmit
position.
This leatule
rnay be disabled,
i J d e s i r e d , b y o p e n i n g t h e m i c r o p h o n e
case and permanently
connecting the
contacts which control
the microPhone.
ANTENNA
Any of the common antenna systems
de-
signed for uEe on the high frequency
amateur
bands may be used with th€
Swan transceiver,
provided
the input
impedance
of the transmission
line is not
outside the capability
ol the pi-output
matching
network,
An antenna which
reflects
a standing wave !atio on 50 or
? 5 o h m r r a n s m i s s ; o n l i n e , b e l o w a P p r o x i -
matety 4: I at the proposed oPerating fre -
q u e n c y , o r a s y s t e m t h a ! r e s u l t s i n a
transmission
line iiput
impedance
that
is essentially
resistive
and between l5
and 500 ohlns will
take power from
the
transceiver
with little
ditficulty.
If tuned
open-wire
trallslnission
line is used to
excite the antenna,
a suitable antenna
tuner should be used between the trans -
ceiver
and the antenna to Provide a
reasonable
irnpedance match between the
unbalanced coaxial output and the balanced
open-wire
line.
Methods
oI constructing
a n d o p e r a t i n g s u c h t u n e r s a l e d e s c r i b e d
in detail in the ARRL
Antenna Handbook,
and sihilar
publications.
Fo!
oPeration
o n t h e 7 5 - a n d 4 0 - m e t e r b a n d s , a s i m P l e
dipole antenna,
cut to resonate in the
rnost used poltion
oI the band' will
Per-
forrn satisfactorily.
For operation
on
t h e 1 0 , I 5 , a n d 2 0 m e t e r b a n d s , t h e
efficiency
of the station will
be Sreatly
i n c r e a s e d i f a g o o d d i ! e c t i o n a l
r o t a r y
antenna is uBed.
MOBILE
ANTENNA
M o b r l e a n t e n n a r n s t a l l a t i o n s a r e c r i t i c a l ,
since any mobile
antenna fo! use on the
h i g h f r e q u e n c y b a n d s r e p r e 6 e n t a a n u m _
ber oI cornpromiBe6.
Many alnateurs
Iose the ef{iciency
oJ their antenna through
improper
tuning.
Points to remernber
about the rnobile antenna used with the
Swan 400 are:
I,
The rO" o{ the antenna loading coil
BhoIrId be a6 high as possible.
There
a r e s e v e r a l c o m m e r c i a l m o d e l s
a v a i l a b l e w h i c h u s e h i g h " Q " c o i l s ,
including the Swan Model 45 and
M o d e l 5 5 5 b a n d " S w a n t e n n a s . '
2.
The loading coil must be caPable oJ
handling the power of the Model 400
without overheating.
In TUNE
position,
the power outPut of the
t r a n s c e i v e r I n a y e x c e e d 2 5 0 w a t t s .
wide
spaced, heavy wire loading
coils are e s sential,
9
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