Philco Model 4 ShortWave Converter (Nov 1931)
The model 4 converter does not contain a loudspeaker, nor does it have an audio detector nor any stages of audio amplification. These
functions must instead be provisioned by a standard broadcast receiver to which the converter must be connected. The model 4 then
serves to extend coverage all the way to 19mc, in three bands:- 1.5-3.6mc, 3.6-8.5mc and 8.5-19.0mc. It connects to the antenna and
ground of the standard broadcast receiver via a heavy, screened cable. To operate the converter the standard broadcast receiver is tuned
to 1000kcs and the converter's bandswitch and tuning control are then used to roam the shortwave bands.
The model 4 uses three tubes, a type 27 (oscillator), 24 (mixer) and 80 rectifier. The schematic is available here, courtesy of NostalgiaAir.
Converters such as this one were a compromise at best. There were now two tuning dials to adjust, there was always the possibility of
interference at 1000kc due to transmissions in the standard broadcast band (though the converter did provide a 1000kc wave-trap and
heavy screened cabling) and there was no means for providing AGC to the converter unit (the better receivers of the day incorporated
AGC). Nevertheless, similar units were offered at the time by several manufacturers.
functions must instead be provisioned by a standard broadcast receiver to which the converter must be connected. The model 4 then
serves to extend coverage all the way to 19mc, in three bands:- 1.5-3.6mc, 3.6-8.5mc and 8.5-19.0mc. It connects to the antenna and
ground of the standard broadcast receiver via a heavy, screened cable. To operate the converter the standard broadcast receiver is tuned
to 1000kcs and the converter's bandswitch and tuning control are then used to roam the shortwave bands.
The model 4 uses three tubes, a type 27 (oscillator), 24 (mixer) and 80 rectifier. The schematic is available here, courtesy of NostalgiaAir.
Converters such as this one were a compromise at best. There were now two tuning dials to adjust, there was always the possibility of
interference at 1000kc due to transmissions in the standard broadcast band (though the converter did provide a 1000kc wave-trap and
heavy screened cabling) and there was no means for providing AGC to the converter unit (the better receivers of the day incorporated
AGC). Nevertheless, similar units were offered at the time by several manufacturers.
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Based upon the chronology of Philco
newspaper advertising, the Philco model
4 short-wave converter made its public
debut in November of 1931, in time for
the Christmas season. Its 1931 list price
was $39.50, complete with Philco tubes.
It was introduced at a time when there
was a growing interest amongst listeners
in the reception of foreign broadcasts on
the shortwave bands. Since Philco did
not offer a self-contained "all-wave" set
for sale at the time (it would be another
half year or so before they did, in the
guise of the model 43), the model 4 was
likely produced as an interim solution,
intended to help satiate public demand
until their all-wave models were avail-
able. It's also possible that Philco was
testing the waters for shortwave using
this converter, in advance of committing
to full-out production of all-wave models.
The model 4 converter was designed to
sit beneath a table-top radio such as a
model 70 or 90, or to sit atop of a floor
model, such as the 111.
newspaper advertising, the Philco model
4 short-wave converter made its public
debut in November of 1931, in time for
the Christmas season. Its 1931 list price
was $39.50, complete with Philco tubes.
It was introduced at a time when there
was a growing interest amongst listeners
in the reception of foreign broadcasts on
the shortwave bands. Since Philco did
not offer a self-contained "all-wave" set
for sale at the time (it would be another
half year or so before they did, in the
guise of the model 43), the model 4 was
likely produced as an interim solution,
intended to help satiate public demand
until their all-wave models were avail-
able. It's also possible that Philco was
testing the waters for shortwave using
this converter, in advance of committing
to full-out production of all-wave models.
The model 4 converter was designed to
sit beneath a table-top radio such as a
model 70 or 90, or to sit atop of a floor
model, such as the 111.
| New! New! Philco Self-Powered Shortwave converter. This converter gives you all the world of radio: London, Paris, Berlin, Rome, South America, Asia, Australia, Ocean liners on the sea, air-liners a-wing. Police calls, every romance, mystery and thrill of the air. Self-powered, non-regenerative, can be used with ANY make of radio receiver. Complete with its own tubes and its own power pack. |
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