NUE-PSK Digital Modem

Supplying Power to/from the Modem  

Proper Use of the +V wire in the Radio Cable



This is a CAUTION NOTE for use when wiring your own connector for the cable to your transceivers ...
The +V wire on the unterminated end of the cable going to your transceiver is HOT, meaning that +12V is being supplied to the radio when the modem is being powered.
The +V wire is red on Type A cables, and brown on Type B cables ... see to identify which type of cable was provided with your modem.
The normal use of this line is for the modem to supply power to a small transceiver like the PSK-xx boards, or conversely for the rig to supply power to the modem.  This way you could conveniently eliminate a second battery or power cable from your station set-up.
But you cannot do BOTH ... i.e., you cannot connect the hot +V line from the modem to the rig connector that also supplies voltage out its accessory/data jack!  One of the two devices will certainly lose the battle and fail.
(One NUE-PSK modem owner mistakenly attached the +V line on the modem cable to the +5V pin on his transceiver's mic connector.  Thus, we think his K2 is damaged.)
IF DESIRED ... You can safeguard against this condition by cutting the "Y" trace on the PCB near the J3 connector, as described in the manual. This eliminates the flexible "remote power" feature, but perhaps protects against inadvertent wiring.
Otherwise, please be careful when interfacing the modem to your transceivers.  In the next round of the modem production, we will make the default condition "open" for this onboard jumper on the PCB.
And as always, please ask first if you have any questions about interfacing the modem to your rigs. 
73, George N2APB
       & Milt W8NUE

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Page last updated:  March 12, 2008