Category: FT920

Hairpn modified antenna for 40 m band – improvments and updates (h=5.5 m above the ground)

For ease of adjustment I found that it is necessary to mount a gear for variable air capacitors.

SWR graph - 7050 +/_ 50khz 

Resonant frequency = 7071 khz
Bw (swr<1.5 = 268 khz) Bw (swr<2 = 484 khz )

FT920 + SCU 17 – AFSK settings – digital modes

FT920 - data conector pinout
SCU-17 conector pinout (As viewed from rear panel, not from cable!) 


AFSK mode
FT-920 pin 1 Data IN (Audio IN)	     SCU-17 pin 1 Data OUT (Audio OUT)
FT-920 pin 2 GND	             SCU-17 pin 2 GND
FT-920 pin 3 PTT	             SCU-17 pin 3 PTT
FT-920 pin 4 Data OUT (Audio OUT)    SCU-17 pin 5 Data IN (Audio IN)
FT-920 pin 5 Busy	             SCU-17 pin 6 SQL IN (Busy)
Pin 1 (AFSK Input):
Connect this pin to your TNC’s “AFSK Out” or “Mic Audio” output line. The optimum input level is 30mV rms, and the input impedance is 3 k. Your TNC’s audio output level potentiometer will allow you to set the level to the optimum value. This pinmay be used either for 300 baud SSB-mode digital operation or for 1200-baud FM packet. The bandwidth and frequency response are not, however, suitable for 9600 baud operation. Be sure the AFSK-FSK switch on the rear panel is in the AFSK position. For FSK operation (whereby the TNC closes a line to ground to accomplish teletype keying), set the AFSK-FSK switch to FSK, and connect your
TNC’s FSK keying line to Pin 1.

Pin 2 (Ground):
Connect this to the shield(s) of the cable(s) used for connections between the TNC and the FT-920.

Pin 3 (PTT):
Connect this pin to the PTT line from the TNC. This pin, when grounded by the TNC, places the FT-920 into the Transmit condition.

Pin 4 (Audio Out):
Connect this pin to your TNC’s “RX Audio” input line. This is a constant-level (100 mV rms @ 600) audio output line which is not affected by the position of the front-panel AF GAIN control.

Pin 5 (BUSY):
This is a “Squelch Status” pin not generally required for digital mode operation. This pin is held at +5V when the squelch is open, and is grounded when the receiver is muted by the squelch (“nosignal” condition).

FT920 Menu settings (dont forget - USB-DATA mode)

Menu #    Description                   Value for WSPR/FT4/FT8/RTTY
U-45      Packet Freq. Display Offset   0000
U-46      Packet Subcarrier Frequency   2125U

Please note, those values are available for regular rtty tones (2295/2125).