[Ron Ramirez]

Yes, Philco used a "2" prefix on American models to indicate a radio-phonograph in the 1930 and 1931 model years, but then switched to different nomenclature for those in American models in the 1932 season with a series of models with two digits starting with a 2. For example - model 23X used a 91 chassis.

1934 brought about the "500" series of radio-phonographs.

Then in 1936, their radio-phonographs carried the same model numbers as the matching radio chassis, only with a "P" in the model number. Ex.: 116PX used a 116 Code 122 chassis

Anyway...

Sometime in the mid-1930s, Philco added a "2" prefix to export model numbers, such as this 245.

I find it also interesting that this 245 was made for 115 volt, 50-60 cycle AC operation which was essentially the same as the USA standard. I seem to recall that most of Europe was on a 220 volt standard at the time, but I think France may have been using 115 volts then? I don't know about Portugal.

Regarding 39/44 vs 78E tubes. Both are remote-cutoff pentodes, and both have similar characteristics. The main difference is in the basing - the 39/44 has the suppressor grid internally connected to the cathode and uses a five-pin base, while the 78 (and 78E) have the suppressor grid lead brought out to a separate pin, requiring a six-pin base.