520SL with Drake T-4XB amateur radio transmitterFAQ #1777
Question:I saw the question in the FAQ about the resistor value in a model 520 - 39,000 ohms. Does the 520SL use the same value resistor? Mine has a 28,000 ohm resistor in it, and I seem to be having difficulty with getting proper audio output when using it with a Drake T-4XB amateur radio transmitter. Any additional information you might have on troubleshooting the use of this microphone with this transmitter would be appreciated.
The resistor value is unlikely to be the source of your problem. Please read the following to understand the three parameters that determine if a Shure mic will work properly with your radio.
What specifications determine if a Shure microphone will properly operate with your camcorder or your tape recorder or your radio or your computer sound card or your anything!
Shure is often asked "Will microphone model X work with my …….?" While we would love to have the microphone input specifications of each and every device in the world that needs a microphone, it is an impossible task. So for us to help you select the proper microphone, we need you to provide the following three vital specifications for the microphone input of your device. Typically, these specifications will be provided in the Owner's Manual for your device or you may have to call the manufacturer of the device.
VITAL MICROPHONE INPUT SPECIFICATION #1
Typically called "Input Sensitivity" or "Nominal Input Level", this specification indicates how large of a signal the microphone must supply to satisfy the microphone input of your device. This specification might be given in millivolts (mV), or volts (V), or in a minus dB form (-dBV, -dBm, -dBu, -dBs).
In the Shure product line, there is a wide variation of signal levels available depending on the microphone model. If you select a microphone whose signal level is too low for your device, the audio will be noisy and low in level. If you select a microphone whose signal level is too great for your device, the audio will be distorted and unintelligible. Proper matching of the microphone's signal level to your device's required input level is imperative.
VITAL MICROPHONE INPUT SPECIFICATION #2
Typically called "Input Impedance" or "Actual Input Impedance", this specification is important as it will determine the proper impedance range of the chosen microphone. This specification will be given in ohms. Contrary to popular audio mythology, the impedance of a microphone does not need to match the input impedance of your device.
In the Shure product line, there are multiple impedances available depending on the microphone model. If you select a microphone whose impedance is lower than or equal to your device's input impedance, the microphone will work if it provides the proper signal level (see #1 above). If you select a microphone whose impedance is greater than your device's input impedance, the microphone will not deliver its full signal level to your device and the audio will be noisy and low in level.
VITAL MICROPHONE INPUT SPECIFICATION #3
This final specification is the type of microphone input connector on your device, how many connection points are in the connector, and what is the function of each connection point. This specification will be the name of the connector, such as: XLR female, 3.5mm mini-phone plug, TRS 1/4" female phone jack, screw terminals, TINI QG connector. Each of these has at least two connection points and most have three (or more) connection points. It is imperative that the function of each connection point be known so that the proper microphone wiring can be determined.
In the Shure product line, there are many wiring schemes available depending on the microphone model. If the microphone connections are not properly matched to your device's input connector, there may be no audio, or funny sounding audio, or the microphone might be damaged if there is an unknown voltage appearing on your device's connection points.
As you can see, there are many variables that affect whether a particular microphone will work with your device. Shure will be happy to assist in your microphone selection, but to do the job correctly, we need you to provide the pieces of this technical puzzle that Shure does not have: the audio input specifications of your device.