Vertex Standard FT-1000MP manual Digital Modem TNC, WEATHERFAX, ETC. Interfacing

ACCESSORY INSTALLATION

DIGITAL MODEM (TNC, WEATHERFAX, ETC.) INTERFACING

The MARK-VFT-1000MPoffers special features for digital modes, such as a built-in digitally-synthesized AFSK generator for RTTY and AMTOR terminal units, IF bandwidth optimization and automatic display off- sets, and an 18-ms transmit-to-receive turn-around time.

Low-level Main Receiver audio output is provided from the rear-panel RTTY and PKT jacks, and is unaf- fected by front panel volume control settings. If you prefer to use Sub Receiver audio for TNC input, switch S3001 (located on the AF UNIT circuit board, inside the transceiver, between the DVS-2and PKT connec- tors) can be moved from the MAIN to the SUB posi- tion.

Audio level is 100 mV from both jacks. The RTTY level is fixed; however, PKT audio level can be adjusted by potentiometer VR3010. In many cases, it is easier to perform level adjustments at the TNC.

DIGITAL MODES WITH A TNC

OR COMPUTER SOUND CARD (PSK-31)

The explosion of new digital modes of amateur com- munication means that you will want to make connec- tions to your TNC and/or computer as “standardized” as possible. Generally, this will mean that you will want to connect your transceiver in an “AFSK” environment. On the MARK-VFT-1000MP, the PACKET jack is the “AFSK” connection port, while the RTTY jack is an “FSK” connection port. In the AFSK mode, the TNC or computer generates the data signal as a set of audio tones, while the FSK mode uses a closure to ground (in the TNC or terminal unit) to cause the transceiver to generate the “mark” and “space” tones.

PACKET TONE INFORMATION

TNC Tone Pair	Tone Center Frequency
1070/1270 Hz	1170 Hz
1600/1800 Hz	1700 Hz
2025/2225 Hzø	2125 Hzø
2110/2310 Hz	2210 Hz

øindicates default setting (used by normal convention)

MARK-V FT-1000MP Operating Manual page 15