User manual SENNHEISER SM 1008

[. . . ] The most frequently used unit, for this application, is the Model MD 214/1 Lavalier suspension microphone. Besides double internal suspension, which renders this microphone strongly resistant to noises produced by friction, the Model MD 214/1 dynamic lavalier microphone has a shaped frequency response that compensates for attenuation of high frequencies caused by the chin of the speaker. The Model 405-T directional hand-held microphone can be used in a similar fashion, worn in an outside pocket, permitting the transmitter to be switched on and off by means of the switch on the microphone. The Model MM 61-2 fountain pen microphone and Model MM 24-2 lapel microphone are even more inconspicuous, although their transmission quality is not as good as that of the previously-mentioned microphones. [. . . ] When the automatic squelch feature is not required, the squelch contra I can be lett at position 1. In order to reliably check operation it is advisable to switch on the transmitter and walk over the entire transmission area while a second person observes the field strength indication. Excessively low antenna voltage, indicated by a pointer on the lett-hand side of the scale may be impraved by reorienting the antenna. , . . . i I ~ E C'M 3. 2 Microphones In operating the micraphones it is merely necessary to note that directional types (MD 4008, MD 405-T, MKH 404 and MKH 804) should be pointed directly at the sound source wherever possible, since they are naturally less sensitive to sounds coming from the sides and rear. ~~ '- beliebig j 3. 3 Receiver Model EM 1008 The receiver is switched on by depressing the "ON" push button. In battery operation it is also advisable to depress the "battery test" push button to determine whether the pointer deflects weil into the red range of the indicating instrument, indicating an adequate reserve. The same channel selected on the transmitter must be selected by depressing the appropriate button on the receiver. As soon as the transmitter is switched on, the instrument will show the fjeld strength. The pointer must as desired '-' J) 4. Special situations 4. 1 Diversity reception Dipole antenna construction For particularly important applications, where not even the slightest temporary reduction of transmission quality can be tolerated, it is possible for two or Fig. 11 6 more receivers to be operated in the diversity mode. Since it is highly unlikely that field strength minima will occur simultaneously at two different antenna sites, the antennae of the two receivers should be located at a distance of several yards from each other. The two receivers must be connected to each other, the cables provided for diversity operation being inserted into the 'diversity' sockets. The equipment connected to the 'output' socket of only one receiver will then automatically be fed by this receiver, or by both receivers in common, when both receive a sufficiently high antenna voltage. For this application, it is recommended that a folded dipole be prepared from 240-ohm TV antenna cable. A 12 foot long antenna cable is shorted at both ends. Then, one of the two conductors is cut in the center and connected with the conductors of a lead-in cable of any desired length. The folded dipole thus obtained must be connected to the anten na socket on the front of the receiver marked '240 ohm'. The actual dipole section (12 feet long) should then be vertically oriented. 4. 3 Special frequencies While the standard carrier frequencies are set to 36. 7 and 37. 1 MHz, the system can also be supplied with any two frequencies between 25 and 45 MHz, (with a frequency spacing of 0. 3 to 0. 5 MHz), as an optional extra. input, an additional balanced, ungrounded output voltage of 2 mV, with a source impedance of 10 ohm, is available at the contacts 2 and 4 of the 'output' socket. This output can be connected to the low impedance, bai anced microphone input of an amplifier. () 4. 7 Hum 4. 4 Tape recording A changeover contact operated by the squelch circuit of the receiver is accessible at the 'auxiliary contact' socket. This changeover contact enables the transports of tape recorders to be operated by electrical remote control Since the receiver is al ready connected to ground via the ground contact of the AC power plug, it is essential to prevent ground loops when subsequent amplifiers or tape recorders are connected. Regardless of whether the subsequent amplifier has a balanced or an unbalanced input, the shielding of the amplifier cable must be continued to the contact on the amplifier housing. On the receiver side, the screening shielding should remain unconnected and must, therefore, be kept from touching contact 2 of the standard plug. If, on the other hand, the grounded plug is replaced by a standard plug which does not automatically ground the equipment, it will be necessary for the receiver housing to be directly grounded via aseparate line, or connected via the cable shielding, to the amplifier ground connection. [. . . ] Signal-to-noise ratio at 40 kHz swing and more than 20 f-lVantenna voltage. Reception trequencies . . . . . . ;;;;3% > 50 dB 36. 7 MHz and 37. 1 MHz 26 db signal-to-noise ratio with swing ot 25 kHz . . , . . . . . . . Adjacent channel rejection (400 kHz spacing) . . Power supply tram 2 flV approximately 50 db . [. . . ]