Epson MFJ-1278B manual Method 1 Direct Connection to Microphone and Speaker, Calibra

MFJ-1278B MULTI-MODE RADIO INTERFACING

RADIO INTERFACING METHODS

The MFJ-1278B allows radio connection without any modifications to the radio or any signal balancing devices in the cables. There are two types interfacing methods presented in this chapter.

Method 1: Direct Connection to Microphone and Speaker

For Method 1, shown in Fig. 3-5, the MFJ-1278B's audio is fed directly into the microphone connector or similarly connected auxiliary jack. The output of the MFJ-1278B will be adjusted to give a proper modulation level. The receiver audio will be taken from an earphone plug or speaker jack and fed directly to the MFJ-1278B. The user can connect a monitor speaker to the SPEAKER jack of the MFJ-1278B. This allows you to monitor the transmit and receive audio on the channel.

Fig. 3-5 Method One Interconnect.

The transmit audio levels for both radio ports are factory preset at 250 mV p-p to be compatible with the mic input of most radios. However, if the transmit audio is too low or distorted, then adjust the appropriate output level control as stated in the section. Use the following procedure to calibrate:

Transmit Audio Level Adjustment for Method I Interface

1.Connect your MFJ-1278B and radio as shown in Fig. 3-5. Turn on the MFJ-1278B and computer and start your terminal program. Connect the radio to a dummy load and listen to the transmission with another nearby radio.

2.Enter the modem calibration procedure by typing

CALIBRA

followed by a carriage return. Press the K key on your keyboard to key the transmitter, then