Alignment Procedure - GE MASTR II Maintenance Manual

MODULATION LEVEL ADJUSTMENT
The MOD ADJUST (Rl27) was a d j us t ed to the prope r sett i ng b e f o re s hipment and shou l d
not normally requi re r eadj ustmen t, Thi s sett inv; permi ts app r o x imate l y 75';:f. modulation for
the avera g e voice l evel . The audio p e aks which would cause ovormo du l a ti o n are clipped by
the mo dulat i on limi ter , The limite r, i n c o njuncLiun with the de-em p h a sis network , i nstan -
t aneou s l y limi ts t he s l ope of th e aud j o wave to t he mod<.ll.ator, th ere by tH'oven tin g over -
mo dulat ion wh i le p reserving in t e l l igib ili t y .
TEST ~U IPMENT
1 . An aud io osc i llator (GE Mode l 4EX6A l 0)
2 . A frequen c y modulation moni tor
3. An output met e r or a VTVM
4 , GE Test Set M o d els 4 I:X3Al l or 4 EX8Kl2
PROCEDURE
1. Connect the audio oscillator and the meter aeross audio input t ermina ls JlO
(Green- Hi) and ,Jl l ( Blac k - Lo) o n GF. Tes t Set , c, r a c ross P90 2-6 ( Mik e Hig h )
th rough a 0. 5 microfarad ( or l a r ger) DC blocki.n g c apac itor, and P902 - 5
(Mike - Low) o n t he Sys t e m Boa rd.
2. Adjust the audio o s c illator fur 1 - Vo lt RMS a t 10 00 Hz .
3. For transmitters wit hout Cha nnel Gua rd , s e t ' • !OD ADJUST HJ 27 f o r a '1 , 5-kilo-
h ertz swing with the d evi at i o n polari ty whic h g ive s t h e hi g hes t re a di ng as
indicated on t h e frequency mod u lati on moni tor .
4 . F o r transmi tters with Chan n el Guard, set Channe l Guard
~IOD
MlJ UST Hl28 for
ze r o tone devia t i o n. Ne xt , with th e 1-Volt :-d .,n<t l at 1000 Hz app l i e d , set
MOD ADJUST Rl27 tor a 3 , 75 kHz d e viati on .
ThL'" t'L'I• lOV<• i:l1e
sil-{na 1 fl·om the
aud io oscillator a nd s et Cha nnel Guard MOD
.IIJ.Il
'iT 1( 12~
I'm·
0 .75 kHz t o n e
d eviation .
5. F or multi-fr eq u ency transmi tte rs, set the deviatio n a s d esc ribed i n Step s 3
or 4 on the channel produc i ng t he l a r gest amo un t o f devi a t i o n .
PA POWER INPUT
For FCC p u rposes, t h e PA power input c a n be determ i n e d by measuring the PA suppl y
voltag e and PA current , and using t!1e f o l l owi ng f ormula;
.Pi = PA voltage x PA c urnent
wh ere :
Pi i s the power i nput i n Watts,
PA v oltage is meas ured with Te st Set Mode l 4EX3All in Po;;itirHl G o n the
15- Volt r ange (read as 15 Volts f u l l sca l e ), a nd wi th t h e pnL1t"i t v s witc h
in t h e (-) positio n. With T est Set Mode l 4EX8Kl 2, use th e fl• l'u -.J. tio n a nd
the 1 - Volt range ( rea d as 15 Vn lts full s r ale) , wi th the
ll l GI!
:::.E~ S ITIVITY
button pressed an d the pol ar ity switc h i n the (-) p o:;;i i.i o n .
PA cur ren t i s measured with the Test Set in Posi tion G in
t ih!
'l'e :-;t 1 position,
and with t he HIGH SENSI TIVI TY bu tton p r e ssed ( 3 0 ampere s fl;l l sca l e ) .
Example:
P 1 = 12 . 4 Volts x 8.5 amperes
· ~
10 5 , 4 W a tts
ICOM FREQUENCY ADJUSTMENT
Firs t , che ck t h e f req ue1 1cy to d e ter mine if any adjus t me nt is requ i red. The f re-
q uency Nhou l d b e set wi th a f r equ e nc y me ter or cou nter with a n a bso l ute a c c uracy t hat
is 5
to
10 t imes better than t he tol erance to be main t a i ned, and wi t h t he e ntire radio
as near as possi b l e t o a n ambien t temp er a ture o f 26,5 "C ( 79.8 "F ) .
llASTR I I I COMs s hou l d be rese t only when t he freq uency s hows dev iati ons i n exc e ss
of the fo l lowing limits :
A.
±0 . 5
PPM ,
when the r adio i s at 26 . 5 'C (7 9, !l "F).
B. ±2 PPM a 1 . any other t e mpe r a t u r e withi n t he ra ng·e o f - 5 ' C t o +55 "C
( +23 °F to + 131 " F ) .
c . The s peci f i ca t ion limit (+2 P PM o r ± 5 P PM) a t any tempera ture within
Lhe rang es of -40 "C t o -S " C ( - 4 0 "F to + 23 " F ) or + 55 ' C to +"/O ''C
(~ l3l " F t o +1 58 ' F) .
l f an adjus tmen t i s r equ i red, p r y u p lhe ~over on the to p of the I COM t o expose
the tr i mmer , a nd u s e o ne of t h e f o llowing pro c erlu ,· e s:
Jf ~he radi o is a t an ambi ent t emper a tur e o f 2 6 .5 "C ( 79 . 8 "F ) , s e t t ~e osci llator
f o r the correct operat u t g f r e qu ency . · .. - -
If the ra d i o i s not at an am bitml
t emper n ~_uJ:~
... _ o f
2~vc, _
s et t i ng error s can be
minimized as follows:
A . To ho l d se t ting err or t o :t0 . 6 PPM ( which i s c onside r ed reasonable for 5 PPM
I COMS) :
1 . M ain t ain the r arl i o at 26.5 •c ( ±5 ' C) and s et t he o s c i l l ator t o
d es ired frequency, or -
2. Ma i n t a in th e r adio
at
26.5 " C ( ±lO''C) and o ffset t he osc i l l ator , as a
fu nctio n o f ac t u n l t e mpera t ure , by the a mount shown i n Figure 9 ,
B . To hold se tt i ng e r rm· t o ±O . :l~ > PPM ( wl1i c h i s c onsider e d reasona ble for
2 PPM ICO~ls ) : Ma in ta i n uni t at 26 . 5 "C (±5 °C) and o f f se t t he os cil l ato r ,
a s a f u nction o f actual t emperattu·e , by the amou nt sho wn i n Fi gur e 9 .
For exanple:
~ ssu me
the a n bient temperature of the radi o
i~
18 . 5 ' C (65.4 'F) . At
tha t temperature , the curve s h ows a c orrect ion f a ctor o f 0 . 3 PPM. (At 25 MHz , 1 P PM
is 25 Hz .
A t
50 MHz,
1 PPM
i s 50 Hz) .
W i th an operating frequency o f 50 MHz , set the osc il lator Cor a re~ding of 15Hz
(0 . 3 x 50 Hz) higher t h an the licensed operati n g f r equency . I f a ne ga t i ve correc ti o n
fa ctor is ob tained (at temperatures above 26.5' C) , ~et t he osci llat or for t he i ndi-
cat ed PPM lowe r t h an the licensed o per a t ing f requenc y .
DEGREES FAHRENHEIT
61.8 65.4 69.0 72.6 76.6 79.8 83.4 87.0 90.6 94.2 97.8
-
~ + 0.6
~
+ 0 .5
.._, +0.4
a:: +0.3
~
+0 .2
a:::
+0.1
L.&..J
0
>-
-0.1
u
z
-0.2
w -0.3
::::>
0 -0.4
~
- 0.5
u..
- 0 .6
~
~
I
I
I
I
~
,
......
I
I
I
I
I
I
I
I
I
..........._
~
I
............... ..........._ I
~
, ......
"'
I
..........._
I
I
I
16.5 18.5 20.5 22.5 24.5 26.5 28.5 30.5 32.5 34.5 36.5
I I I
-5° LIMIT REF. +5° LIMIT
DEGREES CENTIGRADE
RC-2453
Figure 9 - Freq u ency Char acter i st i cs Vs . T emperatu re
EXCITER
METERING
JACK
J103
MOD
ADJUST
R127
CHANNEL
GUA RD
MOD
ADJUST
R1 28
PA
METE RI NG
JACK J205
5 l ll l1 A l . I I I CI RI C
SYST EM
BOA RD
METERING
JACK
' AN T ENNA
JACK
J906
TRANSMITTER ALIGNMENT
EQU lP~IENT R. E QUIH · , -u
1. GE Test Set \lo del 4 EX3All o r Te s t Ki t 4 EX8 K1 2 ,
2 . A 50 - ohm 'A>·a t meter c o nnec t ed to nntennn jack J 9 06 .
3 . A f r equ e nc y coun t er .
PRF.LJIH NARY ~HF(' • ;:s AND ADJUSTMEN'I S
1 ,
2 .
3 .
1.
s.
P lac e ! COlts on Exc i t e r .Boar d (c r y s t al fr equ enc y ,- ope nlt i ng f r equency 7 3) .
f' o r a l arge cha ng e i n f r e q u e n cy o r a. b a dly
rnis -a li ~ne d
t l'an s mi t t er, p r e - set t he s l ugs i n T l 01
th rou~h
1'108, and LlOl , L l02 a ntJ
Ll03 t o the bot tom of ·t he coil form.
- - - - -- - - - - - -- - - - - -- - -- - NOTE · - - - - - - - - - - -
The t u ,.i ng f l·e q u c n cy for mul t i - .t.req uenc y transr.ti t t ers 1s determ ined hy t he opEn·a t i ng f )'el)uenc}' and t:he
·f~~-;~~:;--
s p r 0;;;
bet~A=ee n ---~
tra n s m.! ttc r s . Re f e r to t he t able bel ow f o r ma x i mu m f r e q ue ncy s prend . ··- - - - ---- _}
F or mu l t i - f i ··eq u e n c y trans mit t e rs wi t h a
fr eq u e ~\cy
:;:; p r ead
lf~ .S - " :>
Lhan Lh a t s pec. ifie d i n column
(1 ) ~ tu :-~c
t he 1:rar:srni t ter s t o t h e l o\1/es t
f r l~ ­
q u enc y .
For freq uen t: . v s p read e x cee d ing t he limits s pec i f i e d i n column ( 1 ), t une the transmi t t e r s us i ng a, cen t e r .freque ncy tunc up I COM. Except the
maximum f rc~.: tte nc y spr e ad c a n be ext~nded to t l w limi l s s pec i f i e d in column (3 ) wi th 1 dB degr adation .
F'o r tuning- ; . . J. Ol , 1..102 , L l 03 . Always tune LlO l , Ll0 2 , LlOJ o n t h e lowest
fre~-tuenc :-1 .
Mul t i-ft ~eq\l (:nc y Tr ans mi t ter Tun i ng
- - -
-
---~ ----
r-- -· - - -
- -- -- -- - - ---------·- -- - --
·-- ]
- - - :--1
Tr a nsmi
1:
t e r F r e q u e ncy Range
~ '' - 3 0 Mllz
:l;; - 36 lUiz
31> 42 !!Hz
•t :~ - 5 0 MHZ
MAX!IIU>I F REQt:EI\'CY SPIH;A D
( 1) wi thou t
c _ c _n _ t_e_ r_tt- n - 1 i~;j
wi t lt
~ent er
t unin g
-----~-------------
.ORO Mit~t.
, 1 00 lt:~z
, 1 20 lEiz
, 140 Mllz
. 1 6 0 \1Hz
. 200 illllz
. 2 4 0 M llz
. 2~0 M Hz
with
ef"'!n t f~l'
tuni n g ( 1 LIU
dB~rad a t H·Jn~
, 320 MHz
I
. 400 Mllr. ,
. 470 Mil>;
j '
. 5 40 l!Hz
Conn ec t the ··ed p l u g o n the GE Test Set t o t he System Boar d me tering j a c k . and tlw Ul ack plug t.o t.h e Exc i te.t· me l el' i ng- jack . Set the polari t y
to
+,
and
.S B (
t h e rar::ge to t h e Test 1 posi t i on ( l - Vo lt pos ition f o1· 1 ~XSK12) :for all adj u s tmen t !:> . NOTE : W i t h t he Test Se t eonncctcd t o t he
PA :neter i ng :a c; k,
t hr~
v ol t age reac 11ng a t posit i on " F' ' " · " '·i t. h the HI GH SENSI T IV ITY button pressed ma y be convc r ::-t :d to dl·ivcr· collf;;•c tor cur r(.'n t
by t•ead i ng L ~1e c u r r ent a s 1 0 :1.mperes fu l l scale . The vol ta~o readi ng at pos i tion "G " •.~o ' ith the ll lCH SENS ITIV I TY b utt on pees t>ed ma y be eon--
ve rt e d to p ,,
col l ectot·
c ut·1·en t by re~t di ng the ctJr r cn t as 30 ~mperes f u ll sc a l e .
Al l adj us tme •r1t s a r e mad e wi t h the t 1·a n s mitter keyed , UnKcy t he t ra nsmit t e r be t we e n step s to avoid u nneces s ary tw at i n g .
--·----
-- -·----- ......
----·-
STEP
Il l li'J·· ';R POS I TION. TUNI NG CONTROL 1\E'l'EH HI:A 0 1 NC- PllOC EDURE
f=-
1 ,
2 .
~ .
L
.
I
6 .
i--
7 .
A
• \ 100-l
13
c
'·'ULT-1
LlOl
L1 02 & J.1 0 3
'l'l01 & . . Tl 02
-4--------- -------
1'103 , T l 02,
Tl01 & T\ 04
... -
Maximu m Tune Ll Ol for maximum mc t.("r r eading .
Maxi mu m Tum~ Ll02 a nd then LlO:~ i o1· the max;i Jll u m rnc t C I' r e a d in r:· .
- -- - ---+-- - - --
$'c(• Pr ocedtu'a
Sec Pr oc edu re
Tune Ll Ol f o :r· a d ip i n me ter r eadi ng, a n d t hen tune T 102 for
ma ximu m meter r eading .
Tun e Tl 0 3 f o r ma x i mu n 1:1e t (~r reading ~u1 d
re- adju s t
T 10 2 and T l Ol 1
for Irtaxiu!.Ufn meter r ead i n;!; . Then tun~ 'fl04. f o r a t.l i p iu ~~~~ te:t·
,I
F
IIULT-3
readin g ,
1'105, Tl 0-4 -,- - - + - S -e - - c - P-l'O _c _e _ < _ lu _r_e- - -- -+- - Tu - n--e - T _l_ 0- - 5- - for maximum nc::;:::-;i nK : : ; re - adj us t '1 '10 4 f or maxim j
Tl06 & Tl07
;~;e~.~~:.~;,,n~;t~~h~~.~~~~~
n:__ror
a d i p in me t or
r ~a ding
and
~=J
G Tl 08 , Tl 07 See Proc e d lJre
•.\lPL- 1 &. Tl06
-- ------ f--· - - ·--- ----+-- - - -- ---+---
n
q JPL- 1 i
fl.t[t ximum
l'l,.tnt• Tl08 f or max imum me ter r eadi ng , ~~ n c.l then re - ~ d_j u !'" t T l 0 7 :=..nd
Tl OG t or ma x i nl\lm meter rea <l ing .
1
~Iove
the bla ck meteri ng plug to the
Po~-e~<\~plifi~~-=~~~~-·-;a<'k
I
I -+- "~~v~A)
8 .
I
R2n1
___ 1 ,
_•_n_d_t _ u _ n_e--C-143--a~~- C - 1 5 _ 6_ - f r•:.~_ a_ x _ i _ " '_ u ~~~~~- - -r _ e _ a_ d _ i ' _ ' g _ .
___ _ _____
J
W i t h
tiH~
bn t tet·y voltage at L3 . 4 \'o lt s o r the l> . .\ collector v e l tage ;
at 1 2 . 4 Volts , s e t Power Ad j us t potent i o meter R26 l on t he PA !.hJa rd
I
f o r the des.i r(~d power o u tput ( f r o m 5 0 to 100 \~a t ts. a t 30- 5 0 i>tllz,
. _ _ _L
o r f r om 7:i t u 100
Wa t t ~
at 2 fl- :30 MiV, ) .
I
t f t he
hat tt.~ ry vo l"!:l~··
Js uu t
a.t
13 . - t .
Vo lt ~ or
t he c o llect or· v o l -
t age a t L2. <1 Vo l ts ana fu .I l r at e d o u t pu t is dcsil•cd ~50 to 100
W a tts <. . t t :lo- r;.o mi., . , o r r r o iJi 75 t o 1 0() Wa t t. ~ a t 25 - : W MH.t.), ~e t
H26l for t he o u tput pov:tlr according to the battery vol ti:t~·e or col-
l ee tor v ol t ap,c shown in "F'ig·u re 10 .
, -
1
- - -- - -- - - -- - - - - NOTE - - -- - - - - - - ---- - --
I
\
~~~~
p;\ co l l ec t o r
voJt a~e
lS met ... ul'€d
a~
ctese1 1hf:d 1n
J
: ~ I' \ POWER I NPLT ">e~t ion .
----~-------------'------
----==--==:.=--·- --:::-==-=---
0 - - • _ _ _ _ ,
LBI - 48 98
DC VOLTAGE
Figure 10
Powe r Outpu t Se tt i ng Chart
ALIGNMENT PROCEDURE
25-- 50 MHz, 100- W ATT TRANSM I TTER
Iss ue 1 9