Yaesu FT-767GX, Руководство по эксплуатации

Страница: 34 / 40

4. 1 5 Tips for AM Broadcast Reception
The FT -767 GX is i d e a l for serious s h o r t w ave
b r o a d c a s t reception - especi a l l y i f you h ave
an a n t e n n a t u n e d for the s h o r t w a v e b r o a d c a s t
b a n ds.
Tune to t h e desired b a n d a n d s e t up
t h e r e c ei v e r s e n si ti vi t y a s d e s c ri b e d in
§ 4. 13. 1 and § 4. 13. 2. Then s e l e c t slow A G C,
and key i n a frequency t h a t is a n even m u l ­
tip l e o f 5 kHz.
Since nearly a l l s h o r t w ave
broadcasting signals are spaced in 5 kHz chan­
nels, press D LO CK and M I C U/D, and use the
PROGRAM or microphone DOWN UP keys for tuning
in 5 kHz steps (we suggest you leave these set
as the program med steps for AM and S S B ) .
Very s t ro n g sign a l s wi l l provide b e s t fid e li t y
when t h e NAR switch i s off, but for weak sig­
n a l s you can reduc e noise by t u rni n g i t on,
which causes the S S B filter to be used for AM.
U n f o r t u n a t e l y, t hi s a l s o r e d u c e s fi d e l i t y
qui t e a bit, and m ay b e unco m for t a b l e for
m u sic, o r long periods o f lis t e ni n g.
A l so, if
rapid fading occurs, you should move the AGC
s e l e c tion to m ediu m.
o c c u r d u r i n g t h e
fadi n g.
Even so, dis t o r tion m ay
f a d e s d u e t o s e l e c ti v e
B o t h o f t h e s e prob l e m s c a n be s o l ve d by using
an S S B m o d e for A M reception ( t his is c a l l ed
E C S S, Exhaul ted C arrier Single Sideband mode ).
M e r e l y se l e c t the sid e b a n d ( L S B or U S B ) t h a t
provides t h e b e s t r e c e p tion.
This m ode h a s
t h e a d d e d b e n e fit o f a l l o wing you t o s u p p ress
int e r fe r e n c e that mi g h t b e caused by an adj a ­
ce n t s t a tion, by s e l e c ting t h e sid e b a n d o n t h e
opposi t e sid e of t h e c a r rier.
H o w e v e r, for
this f e a t u r e to be use fu l, the receiver m u st
be t u n e d ex a c t l y t o the c a r rier f r e q u e n c y o f
t h e sig n a l ( or it wi l l s o u n d a w fu l ) : t his i s
where the 5 kHz program med tuning steps o n S S B
m o d e s a r e u s e ful.
O nce y o u h a v e k e y e d in a
frequency wi t h 5. 00 as t h e l a s t t w o digit s,
the up/do w n keys wi l l k e e p you t u n e d to the
carrier channels when you change stations.
Not e : When the FT-767GX is first turned
on abou t 15 to 30 minutes m ay be required
f o r t h e o s ci l l a t o r s t o s t a bi li z e . T h e
receiver i s s t a b l e en ough for c o m fo r t ab l e
E C S S reception after i t has warmed up.
During AM or E C S S reception, use the S H I FT and
TONE c o n t r o l s to t ai l o r the audio of a b r o a d ­
c a s t as y o u desire. I f t w o A M s t a tion s a r e
c l ose t o g e t h e r y o u wi l l h e a r a h e t erodyne o f
t h eir c a r riers. Use t h e NOT C H fi l t e r t o r e ­
m o v e t h e u n d e si r e d c a r ri e r i f i t i s c l o s e
( under 2.5 kHz ), or the S H I FT control (in E C S S
m ode ) i f i t i s f a r t h e r away ( higher pi t c h ) .
4. 1 6 Tips for
FM
Communications
F M o p e r a tion wi t h t h e FT -767GX uses ± 5 k H z
deviation, which mode i s used o n the upper end
of the l Om am ateur band, and on VHF and UHF.
By conve n tion, e a c h b a n d h a s c e r t ain c h a n n e l
s t eps, which s h ou l d b e set u p f o r s e l ection b y
t h e PRO GRA M a n d microphone u p/down keys
( § 4. 8 ). Press the MI C U/D switch, and set the
S QL con t r o l so t h a t the noise is j u s t si l en c e d
on a c l e a r c h a n n e l .
When fine tuning t h e receiver i n between chan ­
n e l s t e p s, press t h e D I S C b u t t o n a t t h e t o p
l e f t c o r n e r.
This c a u s e s t h e m e t e r to indi ­
c a t e discri m i n a t o r c e n ter tuning : w h e n a
sig n a l is t u n e d in correct l y ( o r w h e n n o sig ­
n a l i s p r e s e n t a t a l l ) , t h e m e t e r d e f l e c t s t o
t h e cen t e r o f i t s ran ge. If t h e m e t e r de -
f l e e t s t o ei t h e r side o f c e n t er, a sig n a l is
b eing r e c eived o f f - c e n ter. You c a n a l w a y s
turn t h e D I S C swi t c h o f f to check sig n a l
s t reng t h a f t e r a signa l i s ' c e n t ered ' .
F o r w o rki ng t h r o ug h r e p e a t e r s, s t o r e t h e
s t an d a r d r e p e a t e r shi f t s for each b a n d i n t h e
o f f s e t m e m o ri e s ( § 4. 11 . 1 ) .
S t o r e y o u r
favori t e repe a t e r o u t p u t frequencies i n t h e
memories for scanning, and use t h e TRA C K func ­
tion when tuning repeater sub-bands.
Use the YM- 48A DTMF microphone to generate
DTMF t o n e s for a u t o p a t chi ng. C l ose t h e PTT
switch while entering digits on the microphone
keypad.
S e e § 4. 7. 4 and § 4. 12 for t o n e b u r s t and t o n e
s q u e l c h o p e r a tion.
- 32 -