Belmont Radio Corp. 8AF25 Schematic

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Product Information:
Model:8AF25
Manufacturer:Belmont Radio Corp.

Schematics Content:

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Page 1:

.3.o>oo..._ com 2 u1:o&oteo ...1 of :o on

?John F. Rider

Page 2:

BELMONT PAGE 20-11
MODEL SAFE]

ALIGNMENT PROCEDURE
Broadcasr Band Sedion l. F. and R. F.

The alignmeni procedure below includes 'Ihe sensiIi-

viIies aI 'Ihe inpuIs of various slages. AII signal inpuI czre eve/GT To izASELUY mms
values are based on' an oulpui of 500 milliwaHs. This gil; 6Av6 POWER "NS
may be measured by disconnecling Ihe speaker voice coil
and subsliluiing a 3.2-ohm resislor across Ihe secondary 55M l
winding of *he oulpur Iranslormer. A reading of 1.27 l
voIIs AC across Ihis resisfor will be approximaIer |2AT7 l n TH r9\ _
equivalenl Io 500 milliwaH oufpul wilh Ihe speaker con- o i A g _A sys/GT
necIad. The volume conirol musf be seI aI maximum. T5
The Iona conIroI musI be sei lor maximum freble. ,5A tn l`l 1 'J

The signal source musI' be an accuraIer calibraled "5er PM \\ Mu; 5AL5 \
signal generanr capable of supplying Ihe frequencies MSW 'NWT no INPUT
designaIed, moduIaIed 30% wiIh a AOD-cycle audio sig- GaAs F" ANTENNA "m

nal. A 400 cycle audio signal is required for Ihe audio
measurement Variaiions in sensilivilies of plus or minus
25% are usually permissable.

Chassis View

Bond Swift/l in AM Posifion. Gong Open, Dummy Anfennu .1 Mid.

SIGNAL
GENERATOR

T0 RADIO

ADJUSTMENTS T0 I! IAAD! ADJUST FOI

High Side of
Volume Conlrol
and chassis

455 Kc. Use Pin 1 of bBAb
microvolls and chassis

Pin 7 of bBA7

Maximum oulpuf
Should be 500

400 cycles. Use

Maximum oulpul
Should be 500

Primary and Secondary of T8.
See chassis view.

Maximum oulpuI

Prlmary and Secondary o T6 Should be 500

See chassis view.

455 Kc. Use

and chassis MilliwaHs
BROADCAST BAND-Il. F. ALIGNMENT
cleat pair-m .a me ni. righr Inna .dp af ilu palm' .lin wma" 'mi ih-
righI hand edge of dial marler a' 'he "frame Ie" when gang is closed.
For adiusfmenf. see dial mechanism illuxlraIion.
SIGNAL GENERATOR
FREQUENCY SIT POINT!! AT CONNECT T0 RADIO ADJUST
'no Kc' Calibralion Marker RADIATION cOUPLING CZ-B for maximum
Use xix fum loop across
_ generator oquui. .
Third Calibrailon ,I | y |,~ , b L AnIenna Trimmer
"oo Kc' irom RighI lc' cm. o c. m. I: CZ-A for _maximum

Check Iraclling aI* 1000 Kc, 600 Kc, and 535 Kc Io be sure osciIIanr is seI correcrly.

Power Supply 105 Io 125 voIIs, AC, 60-cycles; FM Sensiliviiy . (For .5 we" oulpull-SO micro-
Chassis only 75 waHs. volls average.
Frequency Ranges BroadC-'SI' Band-535 l? 162? llc* Power Ouipul ., v. 1.5 walls. 10% disIorIion. 3.0

5"): 7" PM. Voice coil impedance

Seledivi AM-47 kc. broad al 1000 I'imes
*y signalI measured aI' I000 lic. 3'2 ohms' 400 Cycle"
|.F. FM-zso kc. broad a+ 2 rim" Tu!" C?mP|?meM
I.F. FM-470 Irc. broad al 10 limes bBA7, AM converlerl FM 6AVb, AM deIecI'or;

voIIs per meIer average.

? John F. Rider

Page 3:

PAGE >20-12 BELMONT
MODEL SAFZS

IMPORTANT

No alignmen* oi ihe FM seciion oi *his radio should be
a**emp*ed unless you are posii'lve fha* *he circuiis are
in need of adiuslmen* and you have *he necessary equip-

All componenis used in *his radio are exiremely siable
and *he *uned circuifs should require no adiusimen*

AllGNMENT PROCEDURE
FM Band Secfion l. F. and R. F. '

NOTE

The 'following alignmen* is based on *he use oi *he new
Simpson vacuum *ube volimeler which has a "floafing
ground". ln o*her words, *he mefer, when used as a
vacuum 'lube volimefer, can have bo*h *he posifive and
negaiive sides connecled *o poinis above ground and
siill give *rue readings. (See noie "C" below.)

over a long period of lima.

Band Swifch in FM Posifion.

A siandard AM signal generaior is required.

Dummy Anfenna .1 Mfd

SlGNAl VACUUM TUBE Vol-T
cinnamon "mmm" neun connrcnou "Tlglasil'mis Aolusr ron
10.7 Mc. - . BoHom Core Resonance
Use abou* TF Pm :3 thisiALs Primary of T9 should Ee abou*
10.7 Mc. Pin No .I Top Core Zero. Use zero
Use abou* of bAUb See no*e "A" Secondary of T9 cenier scale
.05 voli Ra*io De*ecior See no*e "B"
10.7 Mc. >> - Primary and Secondary v Resonance
Use abou* 1800 2'? 215;; Pm :13' ZhgisibsALs of T7. FM Driver lF should be abou* I
microvolfs See chassis view 3 vol*s
10.7 Mc. - Primary and Seconds Resonance
use abou 4oo "ETS ?l P'" thfsf'sALs of Ts. FM inpu IF should be abou
microvolis See chassis view 3 volis

NOTES ON FM-I. F. ALIGNMENT

o John F.

NOTE "A"-Conneci *wc resislors in saries,lDOK OHMS each. from
Pin No. 7 oi bALS lo chassis (Pin No. 5]. These resi*ors musl
be marched wiihin 5%. Conneci vacuum fube volimeiar befween
#he midpoini of ihe resisiors and pain* n.

NOTE "8"-lf T9 has been *empered wiih. ii is possible ihai no
crossover poinf will be iaund ai iirsf. Careful adiusimen! of boih
primary and recondary is neeesary.

FM-R. F. ALIGNMENT

Check poinler so *hal The righl hand edge oi The poinler slir* coincides wifh *he
righi hand edge of dial marker a# *he ex*reme lef* when gang is closed.

For ediusimenl. see dial mechanism illuslraiicn.

NOTE "C"-~To use a VTVM which does no* have *he "floaiing
ground" fealure, in siep Z above, connec* "ground" side of VTVM
io midpoin* of resisiols (Ncie "A") and "high" side To poin* u.
GENERAL-Inpul signals should be adiusled *a give approximafely
3 volh. Tha raiio delacior is operaling a* a reasonable level a*
#his poin* and will give The hues* indicaiion ef correc* elignmen*
wiih ihe procedure specified.

SIGNAL
GENERATOR POINTER ADJUST
FREQUENCY To "mo CONNECTIONS
Marker *ermlnals for maximum Pin No 7 of
98 Tune in See Noie "B" FM Mixer CZ-C bALS lo chassis.
mc' Gen. Signal belowl for maximum

NOTE "A"~|* a signal genereior wiih *he above fundamenial ire-
quancy is ncl available. if is somelimes possible *o use harmonics.
An ellernaie procedure is lo use a local sia*ion carrier oi Known
frequency *o align 'he FM Band and *o use The vacuum *ube voli-
mehr as above *or resonance indica*ion. A veal carrierl hovleverl
will no* produce 3 volh.

Rider

NOTE "8"-Connec* 300 ohms in series wiih "hor" side of gener~
aior and connec* io lei* hand screw of exlernal FM Anlenna Ter-
minals. Connec* cold side of generalor io righf hand screw.

Page 4:

.m-cEEE* mlm O( mf a+ wfuwczou 3162+020 *cz "m 0:) 222:( You 2_5

BELMONT PAGE 20-13

@L, ,L wig

23 22m Saw @,mcmvwi

o John F. Rider

Page 5:

PAGE 20-14 BELMONT

MODEL 8AF25

REPlACEMENT PARTS INFORMATION

Please specify PART number and chassis model number when ordering replacemen'is.

REPlACEMENT PARTS lIST
Use Only Genuine Faci'ory Replacemenf Paris

(C)John F. Rider

Ref. Na. Pm Nal nemipnon my, Ref. No. Parr Ns. Descripnan Q1y1
CAPACITORS (OllS, TRANSFORMERS, (HOKES
C1A,B,C,D B-BA-17673 Gang inning condenser 1 T1 C-13E-18179 Loop anienna assembly 1
C2A,B,C, Trimmers on gang 3 T2-T13-T14 A-16B~16023 RF choke coil assembly 3
C3 A-201-15142 Trimmer condenser 1 TS 31130-16611 Oscillaiar coil (AM) 1
C5 0-86-12166 5 mmf, ceramic, 10% 1 T4 A-13D-16617 Oscillaior coil (FM) 1
013-49 C-BD'10770 .05 mfd, 200 VolfS, 20% 2 T10 A-165-16613 RF choke coil 1
C1533 C-BD-11730 .01 mfd, 200 vol1's, 20% Z T11 A-13E-1661B RF coil (FM) 1
C1748 A-8F-13127 .0001 mid-dual mica, T12 A-16A-16637 RF choke coil 1
011-34 C-SG-11734 100 mmf, ceramic, 10% 2 T16 B_12A_18137 power hansformer 1
C22 C-BFB-IZO 390 mmf, mica, 10% 1 MISCELLANEOUS
Cz; A436151" 10 mfd| 50 vous 1 A-158-13430 9-prong. miniafurs tube seeker 2
C2440-4Z A-SG-13962 .005 mid, ceramic 3 A-153-10440 8-prong, oc1al sockel' 2
c26-21-2s-ao oss-11732 470 mmf. wanna 20% 4 A~15C-16007 7-Pr?r\9- miniahue 1111" S?=1w1 4
Caz cas-13201 1000 mmr. ceramic 1 MOA-18118 Band change swim' 1
C37-A-B.c~D A.sc-1s1zs 40-40-40 m1111350 vom. 11-14M-18147 AC line cord and Plus 1
40 mfd X25 VOlfS 1 A-23A-16328 Line cord lock 1
C39 CJD-10935 .005 mid, 600 volis, AJR-13050 Dipole socks* 1
"140% _15% 1 AeA-10116 Tuning 511.111 1
C45 C-BJ-11321 .02 mid, 600 voiis, 20% 1 A_2D_10033 Tuning shun bucks* 1
RESISTORS B~18A-17637 5"x7" PM speaker 1
R1 A-ibB-IbbiS Suppressor 1
Ra Mas-15016 suppressor 1 DIAL PARTS
R444 C-qBi-78 22K ohms, l/1 wa", 10% 2 C-6D-17737 Dial scale 1
R540 C-9BI-43 27 ohms, l/z waH. 10% 1 A-ZM416034 Dial mouniing bracke* 2
R6-3-12-19 C~9E1~58 470 ohms, l/z wali, 10% 4 B-6M-17622 Background diifuser 1
R7 C-951-40 68 ohms, V2 Wahl, 10% 1 B-2M-16656 Poinfer bar 1
119-32 0-981-82 47K ohms. l/1 we". 10% 2 A-2D-17627 Poinfer bar brackef 1
R11-23.14 011131.94 4701( ahm., 1/2 wsu, 10% 9 11.31.1402" Pulley 2
R13 C-9Bl-79 27K ohms, 1/2 WEH, 10% 1 B-27A-10102 Shoulder rivei 2
R16 C-YB1-34 3.3 megohms, l/z we", 20% 1 A-53A-10989 Dial strings 60" yd.
R17 C-9BI-54 220 ohms, I/2 waH, 10% 1 8-26118119 Dial poinfer 1
R19 C-9Bi-60 680 ohms, l/1 walf, 10% 1 A-50A-16434 Poli sirip for poinier 1
R20 A>>10A-18117 1 megohm, (volume conirol and A-49A-11324 Tension spring 2
R22 A-11l1-15852 1 megohm, (fone confrol) 1 (ABINET PARTS
R25 093155 270 ohm, 1/2 wa", ,0% 1 msc-1015946 meme cabinef 1

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