Automatic RF sense antenna switch
Automatically Switch Between Transmitter and Receiver
Do you enjoy using vintage tube type transmitters and receivers of your youth? It was a real chore to switch your antenna from transmit to receive and back -- it still is!
This neat little MFJ automatic 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 also provides an auxiliary contact closure to ground during receive (opened in transmit) for an "On-the-Air" sign or other use.
Instead of using RF sense to switch the antenna, a control line input 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.
Works on all modes -- CW, AM, SSB, FM, and digital modes. It handles 200W SSB PEP. Compact 4 W x 2 5/8 H x 1 1/2 D inches.
It has SO-239 coax connectors for antenna, transmitter, and receiver. It has control input, auxiliary contact closure to ground, time delay screwdriver adjustment, power jack. Requires 12 VDC or 110 VAC with MFJ-1312D.