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Philco Model 4 ShortWave Converter (Nov 1931)
Life! Thrills! Action!  Get all the Drama of the Radio World with Philco Shortwave Converter!
Based on the chronology of newspaper ad-
vertising, the Philco model 4 shortwave con-
verter made its public debut in late Novem-
ber or early December of 1931, in time for
the peak Christmas season. Its list price was
$39.50, complete with Philco tubes. It was
the company's first shortwave offering.
Shortly afterwards, in January they intro-
duced their models 470 and 490 (see ad at
bottom of page), which combined into a sin-
gle cabinet a modified version of the model
4's chassis (having power supply removed)
with either a model 70 or 90 chassis with
beefed-up power supply. They advertised
the models 4, 470 and 490 as getting
"everything on the air".

These sets were introduced at a time when
listeners were becoming increasingly interes-
ted in foreign broadcasts on the shortwave
bands. Since Philco did not offer a dedicated
"all wave" set at the time (it would be another
6 months or so before they did, in the guise
of the model 43), models 4, 470 and 490
were produced as interim solutions, intended
to help satiate public demand until their all-
wave models became available.

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. Philco made it clear in their ad-
vertising that the converter was self-powered
and would not degrade operation of the host

The converter contains no loudspeaker,
2nd detector or audio stages. These func-
tions must instead be provided by a standard
broadcast receiver to which the converter
is connected. It extends coverage from the
top of the standard broadcast band through
to 19mcs in three bands:- 1.5 - 3.6mcs, 3.6 -
8.5mcs and 8.5 -19.0mcs. It connects to the
antenna and ground of the host receiver via
a heavy, screened cable. To operate with
the converter the host must be tuned to
1000kcs and the converter's band switch
and tuning control are then used to roam  
the shortwave bands. The converter's on/off
control switches the antenna directly to the
standard set when the converter is turned
off, avoiding any need for tedious manual

The model 4 operates using the super-het-
erodyne principle with just three tubes, a
type 27 (oscillator), 24 (mixer) & 80 rectifier.
The schematic is available at

These converters were a compromise at
best. There were now two tuning dials to
adjust, there was always the possibility of
interference due to transmissions at 1000kcs
in the standard broadcast band (though the
converter did provide a 1000kc wave-trap
and screened cable) and there was no
means of providing AVC to the converter.
Similar units were however offered at the
time by several manufacturers.
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.
173/4 (W) * 12" (D) * 101/4" (H)
Philco Model 4 Shortwave Converter, rear view
Philco Model 4 SW Converter
Connects in a "jiffy" to your radio, and gives you choice of all the air affords.
It is uncannily perfect... amazingly good.
Dec 6th 1931
Dec 6th 1931
Models 470 & 490
Mar 3rd 1932
Dec 1st 1931
Dec 6th 1931
Feb 2nd 1932
click any thumbnail to enlarge
Mar 22nd, 1932
Oakland, CA