Belmont Radio Corp. 889 Schematic

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Manufacturer:Belmont Radio Corp.

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Page 1:


Schematic ,Voltage


'NM noon noT
me Mmmx wAV=_ '695_55?? K Cv I Ta Gamma www Au-rl-_m-A exon-4mm: _ 3|. m
A na 130-159 1500 811111-1/3 w.-10% PARTS
R4 130-60 100?hm-1/3 w.f20% C 102-44 Seetinn of three gang condenser
R5 130-52 50M ohm-l/S 'If-20% T1 111-67 Mw-sw mmm coil Assembly
R6 130-77 10M ohm-1 '01-21% T2 111-68 Broadcast Antenna Coil Assembly
R7 130-110 1 mezohm-l/lo w.-10% 'rs 109-32 MW-SW R. F. Coil Auembly
Ra 106-33 55 ohm-Mum T4 109-33 B. c.-R. F. can Assembly
R9 106-33 30 ohm-Muter 'rs lla-ss M. w.. . w, 0101111101 coil Ammbly
310 106-33 240 ohm-Mm" 't6 110-52 B. C. Om Coil Ananny
R11 130-4 3 megohm-l/J w.-Z)% T7 105-93 lnpuz l, F. Coil 465 kc.
R12 130-38 2 mezohm-1/3 w--20% T8 108-92 01mm: I. F. Coil 405 kc,
R13 101-65 500m ohm-wlume camml L1 114-56 speaker 6"
R14 130-101 100M uhm-Ill w--10% L1 114-65 speaker 141'-11?ld Ruimncklaoo 011m 1.8?
R15 130-100 500M ohm-I/J 'L_-10% L2 104-80 Power Transformer-5040 cycle! I
R15 lvl-ss 50M ohm-Tone Oomrol , 1 s 125-25 Bud swlmh
I R17 lac-wo 10M ohm-2 w.-w1re wound 10% sl 101-65 011-011 swim: on volume conml
NOTE: R8-R9-and R10 in cme unit
Clo 100-20 ,lxzno "425%
cw 103-12 810x275 vayuc lening V01- 000ml T0" Tum!! Band
Cm ",445 sm" PM on-off swimh Camel control swim-

(C)John F. Rider, Publisher

Page 2:


MODELS 888,889

Alianmsl'l'tsTl'i-Tmers BELMONT RADIO CORP.

Notes (c) Re-set external oscillator to 600 KC., and adjust

broadcast series pad (adjustment number 3), to res-

l-Type 6K7 Remote cut-off pentode R.F. ann-,ilifierA onance by rotating condenser to approximately 600
-~Type 617-pentode first detector. K.C., rocking it slowly to and fro until by adjusting
l-Type GCS Oscillator, series-pad maximum output is attained, This adjust-
l-Type 6K7 Remote cut-off pentode IF. amplifier (465 .C.) ment is located on the bottom of the chassis directly
l-Type 6Q7G duplex diode triode second detector, A.V.C. under the variable gang condenser. (See bottom view
~ ype pentode output amplifier. d R t d' t t " " d "b" t'l 't' ' '
l-Type SYSG or 5W4-high vacuum rectifier. < )a?iEUR?ama;??nx:en s a an un l sms] mty Is

l-Tyve 665 Caflmde "Y "ming indicmf- (e) Gika ini tracking and sensitivity is 1400, iooo, and
SERVICE NOTES: 600 kilocycles. Under no. circumstance! had plates
Voltagcs taken from different points of circuit to chassis are "f Wk mm' "cum" t? "mt mann'

measured with volume control full on, all tubes in their sockets
and speaker connected, with a volt`meter having a resistance SHORT wAvE BAND ALIGNMENT:

of 13(1) ohms per volt. These voltages are clearly indicated 535 so 18,1'Mepqele.
on t s Circuit dilm'allL 1. With band changing switch in the short wave position
1131; extreme right 4of its rotation, and with external oscillator
U A E RIAL AND GROUND LEAD? set at 17 megacycles and connected in series with "Dum-
lsigio NggioR?riE CIRCUITED WHILE MAKING my 3" to the antenna and ground leads, make the follow-

(a) Move dial pointer to 17 megacycles and adjust short
wave oscillator trimmer (adjustment number 1) to

All voltages are to be measured with 115 volts on the primary
of the power transformer.

inifrl'xjiagffsscsirsggz irriufiiagisffmmesf Windings a" indifmd (b) ?tdinstdshogi weve RF. ninnnsr (ndinshnent nninhsr
Slam >> an s ort wave antenna trimmer ad'ustmcnt

To check for open by-pass condensers, shuntdeacli condenser , "Limbu- 9), to resonanc?_ ( l

with another condenser of the same capacity an vo tage rating. _ - _

which is known to he good, until the defective unit is located. (?) gifs? 23mg' ',:ggiigfc'lefdfsf'eignsgf 283;ng
Excessive hum, stuttering, low volume and a reduction in all sensitivity

D.C. voltages is usually caused by a shorted electrolytic con- N TEV I . . .

denser, open by-pass condensers frequently cause oscillation Oi ' t '5 extremely necessary m. makmg. an Of these

and distorted tone( adjustments that the fundamental oscillator signal be tuned

in and not the image frequency which will fall below the

DUMMY ANTENNAS: fundamental on the receiver dial. As an example of this
The following dummy antennas are used in aligning and a fundamental _17 megacycle signal can be tuned in not only
are referred to in the following alignment instructions as 2( 17 Un the dial but 3150 a* BPDYOleItely 161 l'llegacycles?

'Dummy 1", "Dummy 2", and "Dummy 3".
Dummy 1:_(1.F.)-Consists of a .l mid. condenser connected MIDDLE wAvE BAND ALIGNMENT:

in series with the external oscillator. 1695 to 5500 Kiloeyclos
Dummy 21 (Broadcasf)-Consists of a 200 mmfd? condenser i. Wim band changing switch in the middle weve position,
and a 20 ohm resistor connected in series center of its rotation` and with external oscillator set at
with each other and in series with the 5 megaeycles and connected in series with "Dummy 3"
with the external oscillator. to the antenna and ground leads make the following ad-
Dummy 3: (Middle and Short Wave)-Consists of a .1 infd. iustmcnts: -
condenser and a 400 ohm resistor 'connecb (a) Move dial pointer to 5 megacycles and adjust middle
ed in series with each other and m Series wave oscillator trimmer (adjustment number 2) to
with the external oscillator. resonance.
(b) Adjust middle wave R.F. vtrimmer (adjustment num-
ALIGNING LF. TRANSFORMERS: (465 K-C.)= ber 10), and middle wave antenna trimmer (adjusb

ineiit number 5 , to resonance.
Pan No' 108'92 output I'F' Transformer (c)'Re~s'et external) oscillator and check sensitivity at 1811)
Part No. 108-93 Input LF, Transformer kilocycles'
These LF. transformers have two adjustments. both of (d) Recheck broadcast band alignment.
which are accessible from the top of chassis (see top view). ,

l. With volume control full on, (the extreme right of its ro-
tation), the band changing switch in the broadcast position,
(extreme left of its rotation), and with the variable con-
denser set to approximately 1400 kilocycles, make the
following adjustments:

(a) Connect external oscillator set at 465 kilocycles, in
series with "Dummy l", to the control grid cap of
the type 6K7 tube, and adjust the output I,F. trans-
former (No. 108-92) to resonance.

(b) With "Dummy l" still connected, move oscillator
output clip from grid of 6K7 to grid cap of 617 and
adjust input LF. transformer (No. 1m~93) to


l. With band changing switch in the broadcast position,
extreme left of its rotation, and with gang condenser
in its minimum capacity position, plates entirely out of
mesh, and with external oscillator connected in series
with "Dummy Z" to antenna and ground leads make fol-
lowing adjustments: >
(a) Set external oscillator to 172) K.C. and adjust broad-

cast oscillator trimmer to resonance. (Adjustment
number 4; see bottom view of coil assembly, Fig. 3)

(b) Re>>set external oscillator to 1400 K.C., rotate vari-
able gang condenser and pick up signal. Adjust
broadcast RF.` trimmer (adjustment number 6) and
broadcast antenna trimmer (adjustment number 7), to _

(C)John F. Rider, Publisher

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