GROUND RADIO BULLETIN NO. 29 - NOVEìàBER 9, 1950 COMMS. DEPT. L.A.D.
12ACX-2/12GLX-2 CHANNEL CONTACTS
Recently several cases of extremely sluggish operation of the channelling system in 12ACX-2/12GLX-2 transmitters has been traced to the channel contacts and solenoids having been lubricated with Royco or some similar heavy grease.
The use of this grease will result in temporary improvement of sluggish channelling systems. However, it will dry out with age and become hard and probably result in complete non-operation of the channelling system. GREASE SHOULD NEVER BE USED.
Where sluggish action of the channel mechanism is encountered, all RF contacts should be cleaned with mineral spirits, carbon tetrachloride, or white gasoline. They should be then examined for roughness, such as pitted or worn surfaces, or burned spots. Any such findings will justify replacement of a contact.
When all RF contacts are in good condition, they then may be lubricated very lightly with white vaseline. Do not use any other lubricant on these parts.
The solenoids and plungers which operate the system should be examined to assure there is no binding of the plunger within the solenoid due to foreign matter, or metal burrs. No lubricant is desired on the solenoid plungers. They are sufficiently slack within the solenoid to never bind from lack of lubrication. Any binding will be from other causes which should be corrected.
The bearings of the vertical rod on which all channel contacts are mounted likewise requires no lubrication, though it may be checked if sluggishness persists.
Practically all sluggishness is caused by friction from RF contacts making and breaking contact. The application of vaseline will correct tnis in most cases. In severe cases adjustment of the friction applied by tne spring contacts may be necessary. Elongated mounting holes on the contacts provide tension adjustments.
Finally, the vaseline should be removed periodically and renewed. The vaseline catches dust, and foreign particles, which will form an abrasive causing contact wear and sluggishness. Channel contacts are an important part of the transmitter and should be kept scrupulously clean and smooth. Cleaning periods will vary from station to station.
A properly operating channel mechanism will shift from side to side with a snap, and will show no signs of hesitation or sluggish action whatsoever.
FORM 9211—2107
