RACORDER - The Marine Black Box
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We have not actually seen the radio or performed this procedure. The following is derived from information from Furuno Technical Support and the FM-8500 Service Manual.
Subject: Monitoring TX and RX Audio for the FM-8500
This was requested by the Navy to Tape Record all TX and RX traffic on the VHF.
J1106 on the rear of the radio has standard audio at 600 ohms on pins 10 and 11 - this should be able to be connected directly to one of Racorder's audio inputs. Looks like pin 10 is signal and pin 11 is ground. Seems that it's coming from an isolating transformer, and I can't tell from the schematic if either pin is actually referenced to ground, so it may not matter which is which.
You will need Furuno's connector P/N 000-508-664 or some other method of making this connection, and a shielded cable with a standard phono (RCA) connector on the other end.
Furuno supplies a P/N 000-138-998 Remote Connector Kit - you probably don't need this.
What you probably need is P/N 000-508-664 = CONN/PLUG SRCN6A21 16P, $49.00 List
You will probably need to change the setup in the radio as detailed below to get the transmit audio.
Program in System Settings:
a) Hook Work: SP to OFF.
b) TX AF Monitor to ON.
The Hook Work SP setting will mute the Internal Speaker to prevent feedback of the Microphone audio during Transmit.