Waiting payment,, MFJ-1708 RF Sense T/R switch

A must have for SDR receiver & Transceiver combination. 
Never used, in origina MFJ box.
INTRODUCTION
The MFJ-1708 RF Sense T/R switch senses transmitted RF and switches your antenna from receive to transmit using a relay. It shorts your receiver antenna input to ground to protect your receiver. It provides an auxiliary contact closure to ground during receive (opened in transmit) for an "On-the-Air" sign or other use. It also has a control line input, which lets your key/keyer or PTT line switch the antenna. An adjustable time delay circuit gives you delayed switching. This prevents your antenna from switching between dots and dashes or between syllable and words.
TECHNICAL DESCRIPTION
The MFJ-1708 RF Sense T/R switch uses a relay, which switches from transmit to receive mode. When no power is applied to the unit, it is in the transmit mode. Once power is applied the relay switches on and the unit is in receive mode. When the unit senses RF or the control line is grounded from a keyer or PTT switch, it switches the relay off and the unit is in transmit mode. The delay adjustment allows you to change how fast the relay switches back to the receive mode. It is adjustable from 0 to 2 seconds. The auxiliary jack provides a contact closure to ground during receive (opened in transmit) for an "On-the-Air" sign or other use.