UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Cobra 150-GTL ( cybernet PTBM121D4X )

Steve G4WCS · 2nd Oct 2019, 10:19 am

thanks, yes it is a nice looking radio.

After a few more nights faffing, and a relay, its all working.

it was bleeping without the relay, but coming through on the speaker, the relay cuts the speaker out on transmit and also gets rid of the annoying DC thump on the speaker when changing from reveive to treansmit. I dont know whay the original designers didnt just use a relay instead of two switching transistors, as they have put provision on the board anyway as part of the on pcb roger beep provision

2nd Oct 2019, 10:19 am	#10
Steve G4WCS Heptode Join Date: Sep 2004 Location: Preston, Lancashire, UK. Posts: 632	Re: Cobra 150-GTL ( cybernet PTBM121D4X ) thanks, yes it is a nice looking radio. After a few more nights faffing, and a relay, its all working. it was bleeping without the relay, but coming through on the speaker, the relay cuts the speaker out on transmit and also gets rid of the annoying DC thump on the speaker when changing from reveive to treansmit. I dont know whay the original designers didnt just use a relay instead of two switching transistors, as they have put provision on the board anyway as part of the on pcb roger beep provision