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46-421 ; Philco, Philadelphia (ID = 298304) Radio
46-421 ; Philco, Philadelphia (ID = 298305) Radio
46-421 ; Philco, Philadelphia (ID = 298306) Radio
46-421 ; Philco, Philadelphia (ID = 298307) Radio
46-421 ; Philco, Philadelphia (ID = 298308) Radio
46-421 ; Philco, Philadelphia (ID = 298309) Radio
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46-421 ; Philco, Philadelphia (ID = 298311) Radio
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46-421 ; Philco, Philadelphia (ID = 507121) Radio
46-421 ; Philco, Philadelphia (ID = 300450) Radio 46-421 ; Philco, Philadelphia (ID = 300451) Radio
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46-421 ; Philco, Philadelphia (ID = 300450) Radio
Philco, Philadelphia: 46-421 [Radio] ID = 300450 576x453
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For model 46-421, Philco, Philadelphia Stg. Batt. Co.; USA:
Q = ebay objnr : 230096102449
Country:  United States of America (USA)
Manufacturer / Brand:  Philco, Philadelphia Stg. Batt. Co.; USA
Year: 1946 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 6: 7C7 7A8 7B7 7C6 50L6GT 35Z5GT
Main principle Superhet with RF-stage; ZF/IF 455 kHz; 2 AF stage(s)
Tuned circuits 7 AM circuit(s)
Wave bands Broadcast only (MW).
Power type and voltage AC/DC-set / 115 Volt
Loudspeaker Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
Power out
from Model: 46-421 - Philco, Philadelphia Stg. Batt
Material Wooden case
Shape Tablemodel, low profile (big size).

Elliptical speaker 4" × 6". Sams photofact folder 465-12 date 10-46 features the Philco models 46-421 and 46-421-1 as the same schematic.

Collectors' prices  
External source of data Ernst Erb
Source of data Collector's Guide to Antique Radios 4. Edition
Circuit diagram reference Rider's Perpetual, Volume 19 = 1949 and before
Mentioned in A Flick of the Switch 1930-1950
Literature/Schematics (1) Photofact Folder, Howard W. SAMS (Folder 465-12 date 10-46)
Literature/Schematics (2) Machine Age to Jet Age II (page 218.)
Literature/Schematics (3) Philco Folder for 1946.

All listed radios etc. from Philco, Philadelphia Stg. Batt. Co.; USA
Here you find 3594 models, 2014 with images and 2924 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Philco, Philadelphia: 46-421
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philco: Make a new Special Inductive Capacitor - IF trap.
Paul E. Pinyot † 2013


How to make a Philco “Special” capacitor.
Philco uses a Special Capacitor that has an inductive series coil added. Philco also uses a special capacitor that has highly inductive qualities engineered in. It is designed to bypass IF to chassis ground. This Philco 46-421 uses one of these as C401. I had to fabricate a replacement. This is how I did it.
To build the coil:
  • First acquired a new polypropylene capacitor of 0.2uf 630volts. The high voltage is what I had in stock. 
  • Use enamel covered magnetic wire.  First soldered one end of the wire to one capacitor lead and clipped it short. 
  • Lay the wire up the middle of the capacitor lengthwise and wrap the coil over top of the magnet wire lead. This holds the wire from slipping.
  • Wrap about a 1cm long coil around the out side of the new capacitor. 
  • Secure the loose coil in place with sticky tape. 
 Make the capacitor
To adjust the coil:
  • Connect a 1 or 2 ohm resistor to the free capacitor lead wire. This resistor will generate a voltage to be measured by the oscilloscope.
  • Connect the ground lead of the o-scope and signal generator to the loose end of the resistor. 
  • Connect the o-scope probe to the junction of the resistor and capacitor. 
  • Connect the signal generator to the loose end of the new coil. 
  • Set the signal generator for 455 kHz IF frequency.
 Set Generator for IF frequency
Adjust the o-scope to display the signal and set an amplitude reference point. The o-scope has a percentage graticule. I set the amplitude for 100%.
Raise the frequency 
Then raised and lowered the frequency. Added or remove coil windings until the signal decreased on either side of 455kHz.   
Lower the frequency
Checked the top end and bottom end frequency at 90% attenuation. Once satisfied with the response replace the sticky tape with heat shrink tubing.
I tried a UL rated safety capacitor with a smaller value but birdies (harmonic interference) appeared across the band. I remade the filter with the original capacitance of 0.2 uf and all the birdies were gone. 
Other reference reading can be found on the “Philco Repair Bench” web site. It has a great functional description of Philco’s Special Capacitors.
Happy Fabricating,
Philco, Philadelphia: 46-421
End of forum contributions about this model