Early French tubes imported to the USA
From 1921 to 1924, tubes appeared in US radio stores known as 'French type tubes'
These tubes often slip between the cracks as unknown or foreign. I struggled with the idea that these french tubes were not at all french in origin, but instead early bootlegs with french names.
Perhaps there were a few US brands copying the french craze, with the rest being true french imports.
The pins on these tubes often 'sag' toward the center making for poor contact. Never try and straighten these, as damage will occur.
Instead, a rig must be created hold the tubes securely, with clips used for pin connections. The base internals are quite fragile.
|Hints suggesting US origin||Hints suggesting imported from France|
|Vac-O-buB brand name breaks french name patterns||Most 4v G-12 envelope tubes have french brand names: 'Le Radion', 'Le Clairton', 'Le Deluxe'|
|Advertising past 1924 suggests price cuts from $1.25 to 59cents. Such cuts imply that a supply existed somewhere being cleared out, which breaks the 'small batch import' pattern||'batches of 500' arriving notices suggest limited or staggered supply. Limited adoption/demand combine with this to suggest very low production numbers.|
|Le Deluxe envelope uses Moorhead glass shape, with vertical cylinder plate design; atypical of french designs||Heavy red & amber gettering match those used by french 'Metal' and Radiotechique amplifier tubes.|
|Pin mounting in bases substandard to available parts or fab techniques of the period in US lamp factories.|
|All 'french' tubes share construction issues around above pin problems; yet a fair number of brands & types exist, which wouldnt be the case if several US mfg were faking french tubes.|
Conjecture exists that suggests Leader & Vacobub were produced by rogue Mazda lamp factories in Chicago. It's a reasonable assertion, but isnt clearly supported as theory.
Perhaps Leader was just an importer - someone who tapped the french imports well enough to create his own distribution chain?
US marketed "French" tubes
|Brand||ID||Voltage||Amperage||Envelope||Plate Type||Getter Type|
|Le Clairton||Detector||4v||G-12 tipped||Vert Cylinder||Clear|
|Le Clairton||CDE 28A Amplifier||4v||(0.6 amp)||G-12 tipped||Vert Cylinder||Deep Red|
|Le DeLuxe||vm. 7-7 Detectour||4v||0,6 amps||Moorhead style||Vert Cylinder||Clear|
|Le DeLuxe||vm. 7-7 Amplification||4v||0.6 amps||Moorhead style||Vert Cylinder||Amber / Red|
|Le DeLuxe||vm. 7-7 Amplification||4v||0.58 amps||G-12 tipped||Vert Cylinder||Deep Red|
|Le Premier||Detector||G-12 tipped||Vert Cylinder||Clear|
|Le Premier||Amplifier||G-12 tipped||Vert Cylinder|
|Vacobub||Detector||G-12 tipped||Horiz Cylinder||Clear|
|Vacobub||Amplifier||G-12 tipped||Horiz Cylinder||Deep Amber|
French made 'Telegraphie Militaire' TM tubes made between Oct 1915-1922 (pre thoriated filament)
|Brand||Grid length (cm)||Grid length (in)||Plate length (cm)||Plate Type|
|Compagnie de Lampes - Metal||1.6cm||0.630in||1.5cm||Horiz Cylinder|
|Grammont - Fotos||1.9cm||0.748in||1.5cm||Horiz Cylinder|
Initially I imagined trying to measure the length of the grid, but it's easier than that. If the plates are both 1.5cm, then the CDL-Metal tubes will have 0.1cm of legth 'longer' than the plate, split into 0.05cm on each side. The Fotos tubes will have 0.4cm of length 'longer' than the plate, split into 0.2cm on each side. (0.019in vs. 0.078in)
0.019in is about the width of a mechanical pencil lead, 0.078in is about the width of a wooden matchstick. If it sticks out anything but a tiny bit, it's likely made by Grammont rather than CDL. This is only useful in comparing TM tubes of this earliest era. (1917-1922)