August 1941 Radio-Craft
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
The Radio Service Data Sheets that were published in Radio-Craft usually seem to have more
information included than those published in other magazines, at least in the same era (1940-ish). It might
have to do with how much material is provided by the manufacturer rather than a decision by the magazine
editors. Anyway, here are the schematics, chassis layout, and service info for the Lafayette Model B-100
through B-103. Believe it or not, there are still people searching for such data.
Lafayette Chassis Model B-100 (Table Model B-103; Console Models
B-101, B-102) Radio Service Data Sheet
A 9-Tube, 5-Band A.C. Superhet., with Tuned R.F. Stage on All
Bands; A.V.C.; Automatic Bass Compensation; High-Q Loop Antenna;
Self-contained Counterpoise Antenna; Provision for Outdoor Antenna;
Mechanical 6-Pushbutton Tuning; Edge-lighted Sliderule Dial; Tuning
"Eye"; Provision for Phonograph or Automatic Phonograph and Recording
Microphone (and therefore Television and F.M. Adapters). and for
an External Loudspeaker. Consoles use up to 14-in. Speaker; Table
model, 8-in. Power Consumption, 75 Watts (117 V., 60 cycles); Power
Output, 9.5 W. undistorted, 11 W. max.
The Model B-100 Chassis is used in a series including phonograph
combinations equipped with an automatic record changer. Models not
equipped with record player are provided with facilities for the
playing of records through the radio set (see illustration showing
parts placement atop chassis and at rear). Volume and tone control
are used in the same manner for phonograph reproduction as for radio
reception. Selectivity at 1,000 times signal strength. 30 kc, broad.
The Tone Control affords radio reception when turned to far right
until a click is heard, and then backed-up for tone control; phonograph
operation is obtained when this knob is turned to the far left until
the click is heard, and then turned forward for tone control.
Setting Buttons. - When setting-up the manual pushbutton tuning
buttons, it is preferable to follow in a kilocycle sequence, starting
with the lowest kc. setting at left. To set a button, unlock the
pushbutton mechanism from the back of the radio receiver. On the
drive pulley shaft and at the left side (from the back of the radio
set) of the pushbutton tuning assembly is a locking screw (see Fig.
1). Turn the manual tuning knob until the locking screw is available
and loosen it with a small-handled screwdriver. To set stations
accurately do not jar the radio set or the buttons while the mechanism
is unlocked. Having tuned in a station to accurate resonance, by
means of the tuning eye, hold the manual tuning knob with one hand
and with the other push one of the station buttons all the way in.
Double-check the resonance, meanwhile holding the button all the
way in, then slowly release the button. Do not touch this button
again while the mechanism is unlocked. Now tune-in the second station
following the same procedure; and so-on for the remaining buttons.
After all the stations are set, the mechanism is locked by turning
the manual tuning knob until the locking screw can be easily reached;
with a small-handled screwdriver, the locking screw is then tightened.
Antenna and Ground. - Two built-in aerials are incorporated in
the cabinet. One is a loop type for broadcast reception and the
other is a counterpoise foil aerial used for reception on shortwave
bands. For reception of nearby stations, an outside antenna and
ground are usually not required, however if local noise is excessive
it may be desirable to use an outside antenna, in which case it
should be about 50 to 60 feet long including lead-in. In the console
models, when operating the radio set on broadcast band with the
built-in loop antenna, directional effects are obtained; in the
loudspeaker compartment is a rotatable loop antenna. In the table
model receivers the loop is fixed.
For best shortwave reception an outside antenna and ground are
A wire with an antenna marker will be found coming out of the
chassis. If the loop and counterpoise foil aerials are used do not
connect this wire to anything. If an outside antenna is used, connect
this wire to the lead from the outside antenna. The wire which is
connected to the counterpoise foil aerial should never be disconnected.
On the back of the chassis is the socket for record-player connections.
The cable connector must be a single shielded pin. Part No. BA224.
On the top of the chassis is an A.C. phono motor socket. On the
back of the chassis is a socket to which a microphone preamplifier
may be connected. The speaker socket provides connections for the
record cutter and power for the preamplifier. Dial lamps are bulb
No, 51. bayonet pin type.
Posted April 19, 2015