Dave, My guess is that the duplexer was manufactured for Motorola by Decibel Products from the SP-xxxxx on the model identification plate as pictured in your photos. The duplexer appears to be a pass band type circuit from the separate input and output coupling loops on each filter and from the apparent lack of any notch adjustments.
Normally, there would be a Tee at the junction of the two inside cavities to form the antenna port. All interconnecting cables are typically 1/4 wave electrical length between cavities to include those connecting to the Tee at antenna port. You'll have to measure the existing cables and then do the math and apply the correct VP for the cable type in use at the intended frequency of operation. My guess is that they are a bit short for work in the 70 Cm ham band. Bill, WA8WG From: Dave Sent: Sunday, March 08, 2009 10:45 AM To: [email protected] Subject: [Repeater-Builder] DB duplexer Question I acquired this DB duplexer and need information. The cables were not connected correctly. However I do have them. It is for the 440 band I do know. First question. What would be a good guess of the model # ? Second question, does anyone have the correct cable lengths and where they go? Attached are some pictures. Thanks, Dave KA9GFS
