GROUND RADIO bulletin no. 23 - march 29, 1950 COMMS. DEPT. L.A.D.
AUSTIN LIGHTING TRANSFORMERS
These transformers mounted at the base of Wincharger towers are sometimes subjected to insulation puncture due to lightning flashover. To minimize this occurrence the primary of the transformer should be accurately centered within the secondary with equal distance from the other coil all around. This is easily accomplished by using proper size nipples to obtain correct placement.
Insulation damage can be repaired by wrapping thoroughly with tape and applying several coats of varnish to the wrapping.
The lightning gap on the tower is spaced approximately l/2n between balls for 30 to 40 KV flashover. In making this spacing, operation should be checked to ascertain that the .transmitter RF does not arc across this gap. If it should, the gap is increased until the arcing ceases.
MICROPHONE BOOM
Most FA positions at LAD stations now use an adjustable microphone boom to assist the operators in proper positioning the microphone to their convenience.
The boom in general is not complicated but does require a certain amount of maintenance. This will consist mainly of proper lubrication. A very small amount of thin lubricating oil (SAE-20 or equivalent) should be applied to all moving parts periodically so that smooth, free motion is always available.
These booms sometimes are subjected to unwarranted rough handling. Lubrication will assist materially in their withstanding such usage by relieving strains caused by binding joints.
Screws etc. should be examined for tightness. Microphone wires should be inspected for frayed insulation and exposed wiring. When it is necessary to replace the wiring in the microphone boom, TEST LEAD WIRE (PAA #7101-5588) is recommended. Such wire is very flexible and will withstand movement of the boom without breaking for a considerable length of time* It would be well to requisition sufficient length for replacement purpose to have on hand for the next time replacement is necessary.
This type of wire should only be used with carbon microphones. No suitable wire is carried in stock for low level dynamic microphones and it will be necessary to furnish this on a special requisition.
Keep your microphone and boom in good condition. A breakdown at this point may cause complete non-communication with an airplane when most needed.
FORM 9211—2107
