Shure 440 manual Specifications, Voltage Sensitivity, Model

A.Using the microphone as supplied, the grip-to- talk switch operates both the microphone circuit and an external relay or control circuit. Connect all leads t o the proper terminals of the equip- ment. (See equipment manual). By using the white and shield leads (microphone circuit) or by connecting the shield and black leads together and connecting t o the proper terminals, the grip- to-talk switch will operate the microphone circuit

but the external relay or control circuit is not operated, and the microphone can be VOX operated with the microphone being muted by the switch.

B.By the minor modification of cutting the green lead (see Figure A and instructions below) the microphone circuit i s removed from the switch action and the switch will operate the external relay or control circuit in push-to-talk operation. The microphone can be used for VOX operation and the microphone can not be muted.

The modification is made as follows:

I. Remove the integral assembly of the microphone and switch from the desk stand.

2.Remove the 4-40 phillips head screw from the bot- tom of the switch case and pull out the bakelite re- ceptacle.

3.Disconnect the green wire from pin #3, insulate the bare end of the wire, and put the wire back into the switch case.

4.Replace the bakelite receptacle and the 4-40 phillips head screw.

5.Assemble the microphone and switch t o the desk stand.

To obtain optimum flexibility between either VOX or push-to-talk operation.

The Shure Model A87K Kit will modify the micro- phone by placing a switch in the black lead from the receptacle. The grip-to-talk switch of the micro~honecan then be used t o o ~ e r a t ethe microbhone circuit and the external d a y or con- trol circuit can be operated or NOT operated by grip-to-talk switch by changing the position of the A87K switch. This will permit instant change- over from VOX operation t o push-to-talk opera- tion and still retain the microphone circuit switch t o mute the microphone in either operation.

Operation: No special precautions beyond ordinary care are necessary in the operation of the Models 440 and 440SL Microphones. They will operate satisfactorily under ordinary conditions in hot and cold climates. To retain the full strength of the permanent magnet and t o maintain alignment of structure, dropping or other se- vere mechanical shocks should be avoided.

The 440SL microphone, as supplied, has a switch which i s a momentary contact Inon-locking) t y e. For use as a grip-to-talk switch, grasp t e switch with Kand press- ing the bar with fingers. If desired, the switch may be

converted t o a grip-to-talk, slide-to-lock switch. This may be done by loosening the number 5-40 Philligs Head ma- chine screw, directly beneath the switch ar, rotating the "Stop-Plate" one-half turn and retightening the ma- chine screw. To lock, press the bar and simultaneously apply force downward with the index finger until the switch bar slides and i s locked in position. To unlock, slide bar up with fingers.

Specifications:

		MODEL 440				MODEL 440SL
Height Overall	2	s (61.lmm)			Dia.	9%"	(238.lmm)
Length Overall		3%"	(82.6mm)			7"	(177.8mm)
Width Overall	2	s (61.lmm)			Dia.	5"	(127rnm)
Finish	Gray and Chrome					Gray and Chrome
Net Weight with		3/4	Ib.	(340g)		2v2 Ibs. ( 1 134g)
7' (2.ln-t) Cable
Shpg. Weight		Ifi	Ibs.	(6809)		5 Ibs. (2722g)
with 7' (2.lm) Cable

Voltage Sensitivity

Model 440 and 440SL

Open circuit voltage ......... - 52.5 db ': (2.38 mv)

E.I.A. Microphone Rating GM

- .!.-7,

Sensitivity ............................ 142.3 db,*-.

*odb = I volt per microbar

'8" E.I.A. Standard SE-105 August 1949

Microbar = one dyne per square centimeter

Frequency Response: 300 t o 3000 c.p.s.

Recommended Load Impedance:

100,000 ohms or more

Guarantee: Each micro hone is guaranteed to be free from electrical and mecKanical defects for a period of one year from date of shipment from the factory, pro- vided all instructions are complied with fully. In case of damage, return the microphone t o the fadory for re- pairs. Our guarantee i s voided if the microphone case is opened.