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VHF Transmitter 5-Pin Input Jack Wiring

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The information on this page is for generic microphones.

Ta5f

This termination is required on VHF transmitters and will still work fine on UHF units.

  • PIN 1 Shield for positive biased electret lavalier microphones. Bias voltage source for negative biased electret lavalier microphones. Shield for dynamic microphones and line inputs. This pin is also used as the antenna input on VHF models and should not be attached to the connector body.
  • PIN 2 Shield (ground) for negative biased electret lavalier microphones. Bias voltage source for positive biased electret lavalier microphones.
  • PIN 3 Low impedance microphone level input for dynamic microphones. Also accepts hand-held electret microphones provided the microphone has its own built-in battery.
  • PIN 4 1K ohm source load for non-Lectrosonics electret microphones. Use in conjunction with other pins to provide attenuation of high level input signals.
  • PIN 5 High impedance, line level input (when pin 4 is jumpered to pin 1) for tape decks, mixer outputs, musical instruments, etc.

Caution
On the VHF models do not use the connector body for any electrical connections. A common mistake is to use the connector body as an audio ground. The connector body is already used as an RF ground on the VHF models and no other use is permitted.

 
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RF Bypassing

Some mics require RF protection to keep the radio signal from affecting the capsule, even though the transmitter input circuitry is already RF bypassed (see schematic diagram).

If the mic is wired as directed, and you are having difficulty with squealing, high noise, or poor frequency response; RF is likely to be the cause.

The best RF protection is accomplished by installing RF bypass capacitors at the mic capsule. If this is not possible, or if you are still having problems, capacitors can be installed on the mic wires inside the TA5F connector housing.

Install the capacitors as follows: Use 330 pF capacitors. Capacitors are available from Lectrosonics. Please specify the part number for the desired lead style.

  • Leaded capacitors: P/N 15117
  • Leadless capacitors: P/N SCC330P

All Lectrosonics lavalier mics are already bypassed and do not need any additional capacitors installed for proper operation.

 
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Body Ground

Caution
When wiring the connector, do not use the connector body for any electrical connections. A common mistake is to use the connector body as an audio ground. The connector body is already used as an RF ground on VHF models and no other use is permitted.

Line Level Signals

The normal hookup for line level signals is: Signal Hot to pin 5, Signal Gnd to pin 1, pin 4 jumped to pin 1, and pin 3 jumped to pin 1. This gives a 30dB attenuator that allows signal levels much higher than 3V to be applied without limiting.

If more headroom is needed, insert a 100k resistor in series with pin 5. Put this resistor inside the TA5F connector to minimize noise pickup.

If lower than normal line levels (less than 1V) are expected, use this hookup: Signal Hot to pin 5, Signal Gnd to pin 1, and pin 4 jumpered to pin 1. This provides a 20dB attenuator allowing signals as high as 3V to be applied without limiting.

Wiring Hookups for Different Sources

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