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- SENDING RTTY WITH K3 MTTY INSTALL
- SENDING RTTY WITH K3 MTTY SERIAL
- SENDING RTTY WITH K3 MTTY WINDOWS
The most successful way to use a USB-to-Serial port adapter is to use EXTFSK. MMTTY has provisions for altering the polling rate and speed on a USB port for use with a USB-to-Serial adapter when using such a device to run FSK. Although some operators have had success directly connecting the TxD line straight to the FSK input of their transceivers, I do not recommend this.
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Your FSK circuit is looking for either an open or a ground to shift the frequency of the radio. Your radio’s PTT circuit is looking for a ground to key the circuit and turn on the transmitter.
SENDING RTTY WITH K3 MTTY SERIAL
Why can’t you just connect your radio straight to these pins on your serial port? Because some of the pins will vary in voltage from +12v to -12v (RS-232 voltage levels) and your radio may not be able handle that. RTS is pin 4, DTR is pin 20 and TxD is pin 2 on a 25 pin serial port. You really don’t need to know this either, but don’t you feel better now that you do?Īnd because most computers today use 9 pin serial ports, I failed to tell you what pins would be used for a 25 pin serial port.
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Likewise, I failed to mention pin 3 of a 9 pin serial port, the one used for FSK, is called TxD (Transmit Data).
SENDING RTTY WITH K3 MTTY INSTALL
It doesn’t really matter if you use RTS or DTR, but you might want to know this if you are trying to install jumpers in a RIGblaster Plus or trying to understand why some PTT interfaces use Pin 7 while others use Pin 4 on a DB 9 connector.
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It just happens that pin 4 (DTR – Data Terminal Ready) on a 9 pin serial port does the exact same thing and could be used in place of pin 7 (RTS). However, I didn’t mention that this pin is specified as RTS (Request To Send). While covering PTT and FSK interfaces, I showed a diagram of a simple transistor circuit connected to pin 7 of a 9 pin serial port for PTT. It also has other nice features like allowing FSK transmission from RS-232 outputs other than TxD. EXTFSK is required to key PTT and/or FSK from a parallel port AND when using a USB-to-serial port adapter. There is also information on USB adapters and using EXTFSK on this page. These things are specifics which might help you grasp certain concepts better or help in troubleshooting RTTY problems. There are a few things I didn’t cover on the other pages which are good to know, but not necessary to understand in order to get started on RTTY.
SENDING RTTY WITH K3 MTTY WINDOWS
Drag it away from other windows so they don’t overlap. The familiar MMTTY control panel, called “RTTY Engine 1”, should appear as shown in Figure 3-5. Go to the Interface pull-down menu at the top of the Digital Interface window and select MMTTY as shown in Figure 3-3. If the Main Entry Window is on top of the Digital Interface window, move the Main Entry Window away from the Digital Interface window so they don’t overlap each other. The Digital Interface (DI) window opens up to MMVARI by default.