This question is best posed on the Repeater-Builder list ([email protected]), but I know the answer: A mobile (notch) duplexer will not work at a 600 kHz split. Even a 3 or 4 MHz split results in unacceptable performance.
I have built a portable repeater for 2m, using the special TASMA "portable repeater pair" of 147.585 MHz input and 144.930 MHz output- a split of 2.655 MHz- but I had to use a Celwave 5085-1 duplexer to make it work. The 5085 duplexer is about twice the size of a mobile notch duplexer, and it is intended for splits as narrow as 3 MHz. With careful tuning on a network analyzer and using a 1-to-10 watt Motorola 1225 full-duplex transceiver, it performs very well. For a 50-watt repeater at a 600 kHz split, you will need a full-size set of cavities, which can be built into a foot locker for portability. 73, Eric Lemmon WB6FLY -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of crowltom Sent: Saturday, August 30, 2008 9:06 AM To: [EMAIL PROTECTED] Subject: [EMAIL PROTECTED] VHF Duplexer Hello This is way off topic so... Looking for a mobile duplexer for a repeater project 50 watts max VHF Ham band 600 kHz separation. New or used, as long as it has a small foot print and it works. Small group, no money, help! THANKS
