Challenger 3 Prest-O-Matic (Prestomatic)

• Brand: Synchrophase

Bakelite (color: black or brown) or Plaskon (color: ivory, red or green). The models Challenger 3 and 3 C have a full vision, illuminated Clock-type Dial, as well as Prest-O-Matic (Prestomatic) instantaneous tuning, calibrated in Kilocycles and meters, Tuning Range 173 to 555 meters. Has a wave trap.

For the date see the 3 models, 782-1, 762-L and 782-T in an ad of "Radio Today, November 1937, page 66 and a folder with the same models and more:
Challenger 3, Challenger 3C, 762L, Challenger 5, Challenger 5 L.W., 782L, 782-1, 782T, Challenger 1, Challenger 2 plus the phonograph combination models 782-P8 with Prest-O-Matic instantaneous tuning, 307-P8, 803-P8 and the following models which can be installed with the long wave band for 835-2050 metres: 309-P8, 903-P8, 3012-P8 and 1203-P8.

See also the corresponding Garod models with the same cabinets and chassis, like Challenger I, Challenger III,  782-1 etc. Examples: the schematic for 1203 Series is the same for Garod 1203T, 1203L, 1203-3, 1203-P6, 1203-P7, 1204ET, 1204E1 (1204EL), 1204-3, 1204E-P6 and 1204E-P7.

In questo link sono elencati 188 modelli, di cui 124 con immagini e 61 con schemi.
Elenco delle radio e altri apparecchi della Grebe, A.H. & Co.; Richmond Hill (NY)