Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
I have been scanning and posting Radio Service Data Sheets like
this one featuring the Stewart-Warner Model 03-5A Senior Varsity Radio receiver for many years now.
There are still many people who restore and service these vintage radios, and often it can be difficult
or impossible to find schematics and/or tuning information. The thumbnail image of the Stewart-Warner
Model 03-5A Senior Varsity Radio came from the
RadioAttic.com website.
Stewart-Warner Model 03-5A1 to 03-5A9 (Chassis 03-5A) Senior Varsity Radio Service Data Sheet
Alignment Procedure
An output meter and an accurately calibrated signal generator are required.
(1) Connect the output meter across the voice coil; or, using a condenser in series, connect between
the plate of the 35L6GT output tube and "B-" as shown on the voltage chart. The more sensitive type
should be connected across the voice coil.
(2) Connect the ground lead of the signal generator to the "B-" lug (shown on the voltage diagram)
through a 0.25-mf. condenser and keep it connected in this manner throughout the entire alignment procedure.
Failure to do this may have serious results, as one side of the power line may be grounded in the signal
generator, or bum may be encountered.
(3) Turn the volume control to the maximum volume position and leave it in this position throughout
the entire alignment procedure.
(4) To Calibrate the Dial - Remove the chassis from the cabinet and set it on a fiat surface (insulated
from ground). With the gang in full mesh, the last dial division (just below 55) on the low-frequency
end, should be exactly 4% inches above the table surface. If this is not the case, release the setscrew
in the collar which connects the gang condenser shaft with the tuning unit, and holding the gang in
full mesh, turn the dial until the last division is exactly 4% inches above the table surface. Now re-tighten
the setscrew in the collar. The 4% inch division on the ruler (when measured vertically from table
Posted April 12, 2017
Radio Service Data Sheets
These schematics, tuning instructions, and other data are reproduced from my
collection of vintage radio and electronics magazines. As back in the era, similar
schematic and service info was available for purchase from sources such as
SAMS Photofacts, but these printings
were a no-cost bonus for readers. There are 227 Radio Service Data Sheets as of
December 28, 2020.
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
