Cables and connectors for connection between the PK-232 / PK-900 TNC and Yaesu FT-847 for HF / VHF
There are a few issues to be aware of. In the case of using the Data port in the FT-847, there is a hang time on the PTT that is too long for Packet QSO's to be viable. I posted a message in the Packet Radio Forum that I belong to and another user of the FT-847 had the same issues and resorted to the Front Mic Connector, and rear Ext Speaker for the connection. That started to look a bit of a cable nightmare when dealing with all the other cables I have here. I had a bit of a google around and fell upon a note in a SuperControl.de page about long changeover on the FT-847 and there was another way.
The note said that some people had good results with using a 100nF (0.1uF) capacitor or 200nF (0.2 uF), so I set about trimming off all the nice neat heatshrink that I'd put on when making the cable up. Replacement of the capacitor for a 100nF has speeded up the transfer to one that will now support AX-25 Packet.
Anyway, I learned so you don't have to. You can either build the cable as I have below or experiment with a different capacitor value. There are also notes elsewhere that say to up the resistor to a 2.7k Ohm one but there is little explanation of why.
FT-847 Data Connector for HF Digital Modes
The FT-847 uses a 3.5mm stereo jack for HF digital signals, and therefore is fairly easy to connect to a TNC. The difficulty with the PK-232 is the lack of TNC connectors, if you are not lucky to get cables with your TNC. I didn't with any of my TNC purchases, so looked around in the supplies boxes and USB 5-pin Motherboard headers work just fine. These are wired to a small piece of strip board to populate the Capacitor/Resistor circuit to provide PTT, as designated by the Yaesu Radio User Manual.
The cables need to be at least shielded and wired to provide good ground connections between the TNC and Radio, else ground loops will give poor signals, transmit and receive. I have used JY-8022 Audio Cable (Twin shielded cable, in 8-form), Neutrik 3.5mm Jack and a homebrew TNC connector.
Parts
JY-8022 Twin Audio Shielded Cable
2k Ohm 1/4 watt Resistor
10 uF Electrolytic Capacitor - SEE ABOVE NOTE FIRST
5 pin Female Dupont Connector
REAN Stereo NYS231BG-LL Extra large entry 3.5mm Mini Jack plug
Assembly
Connect as diagram with 3.5mm Jack TRS ;
Tip - Signal T
Ring - Signal R
Sleeve - Ground
Connect Veroboard as circuit diagram ;
PK-232 TNC connector ;
Pin 1 - RX Audio = Signal R
Pin 2 - TX Audio = Signal T
Pin 3 - N/C
Pin 4 - Gnd = Ground
Pin 5 - PTT = Via Veroboard circuit
AEA pin-out for PK-232
FT-847 Data Connector for VHF Digital Modes
The Yaesu FT-847 has two connections for data modes, one for HF data and one for VHF/FM Packet. I detail the HF Data connector to the Pakratt 232 TNC on another page, and this page concerns the VHF/FM connector. This is a 6 pin DIN presentation, in a very small DIN configuration.
This connector, as you can see from the Yaesu diagram below has two speeds, 1200 and 9600 bps. This is indicated on the diagram for the cable ;
Wiring diagram
Yaesu Manual Pin-out for PKT port on FT-847
FT-847 Data Connector for HF Digital Modes on PK-900
Parts
JY-1199 4 core shielded audio cable
5 pin Female Dupont Connector
5 pin Mini-DIN Connector
Assembly
Wire as circuit diagram, ensure shield provides continuity between Gnd and 5 pin Mini-DIN Connector to prevent ground loops and hum.
After the PK-232, I wanted a PK-900 but AEA PK-900 is a rare sight. I found one on E-Bay with only 6 mins left to go. I promptly bid and won so now have one of the best TNC devices made. The connection cable below is for the HF Data port on the FT-847 to the PK-900 using the same cables as for the other PK-232 cables on this site.
Parts
REAN Stereo NYS231BG-LL Extra large entry 3.5mm Mini Jack plug
JY-8022 Twin Audio Shielded Cable
2k Ohm 1/4 watt Resistor
10 uF Electrolytic Capacitor - SEE ABOVE NOTE FIRST
5 pin DIN Connector
Wiring Diagram
