GROUND RADIO bulletin no. 42 - September 8, 1952 COMMS. DEPT. L.A.D.
ENGINEERING DATA
We are interested in obtaining certain engineering data concerning Aerophare Antenna Systems, Antenna Tuners, Transmitters etc., therefore it is requested that the Senior Communications man at each station forward the following information to the DOS’s office at his earliest convenience:
Aerophare Antenna Tuners:
If you have an ATU-12S or ATU-12SL, In which of the three coils is the wire from the "LF Antenna" meter connected? On which turn of that coil, counting from the front, is the wire connected?
If you have an ATU-12W, How many turns from the top of the coil is the wire connected that goes to the meter?
Aerophare Transmitters:
Has it been found necessary to retune the PA stage of the transmitter between wet and dry weather? If it has been found necessary to retune, please report the normal loading, (PA plate current) amount of increase due to weather, and P.A. plate current after retuning.
4-250A Tube:
Users of this type are requested to report their experience relative to balance between two tubes in parallel. Has the change to this type tube minimized the balance problem in the final stage of the 12GLX and 12ACX transmitters?
BOGAN COMMUNOPHONES
The type 253-B Bogan Communophone output transformer, 50L6 to 8 or 50 ohms, Pt. No. 9068-6380 is no longer available.
A type Thordarson T-275-1, 50L6 to 50 ohms, Pt. No. 9068-1775 has been designated as a replacement where a 50 ohm secondary is required. If an 8 ohm secondary is required, the Ground Radio Shop has a supply of these on hand and they will be sent from this stock. When ordering replacements be sure and state which transformer you need.
Also on Page 9 of the Spare Parts Kit, (Dwg. GEN-25B-958-3) please change Pt. No. 9068-6380 transformer, plate to 8 or 50 ohms, T-253-B to read 9068-1775 transformer, plate to 50 ohms, T-275-1.
