PK232.24 1) Stick a decoupling cap between the RTS and CTS lines and earth (he thinks that was where he put them). 2) Strap the signal and frame ground lines together at the TNC and computer end of the RS232 cable. He knows that technically the two are supposed to be separate, but suspects that the problem arises when the signal ground ends up at a different potential from the frame ground. He hasn't had the TNC lock up for 6 months or more. Alex (G1FBY @ GB7BMX) reported that he has had his 232 for two years. One of the first problems he encountered was lockup. All investigations of the unit proved OK. One Sunday his XYL was using the washing machine and dishwasher for long periods of time and the PK232 locked up 6 times. It was run on a fully regulated power supply. He fitted a Radio Spares spike protection socket to the mains plug of the power supply and all has been FB since. ********************** Hope this is useful, 73 de Derek [G4UXD @ GB7OAR]