Hello Morris, I'm glad to heard the that you got the receiver working! Just one question, was the test duplexer tuned to the proper frequencies? Was it desense or just loss of sensitivity when using the duplexer? In other words, were you able to hear distant signals with the transmitter turned off?
73, Joe, K1ike Morris Dillingham wrote: > Well, guys, I promised to follow up with the results of my attempt to repair > the old Spectrum 1000 with the later model receiver. Thanks to Larry and > Joe, I have determined that my receiver is not an SCR200A but probably a > later model of the SCR-200. I obtained at least three versions of the > schematic from this series receiver thanks to these two gentlemen. Of > utmost importance was finding out the transistor part number since my > schematic was the wrong version. I was able to replace the front RF amp > and get the receiver working again. Before doing that, however, I noted the > inadequate wiring, IMHO, in the power supply. The SCR-1000 upgraded PS has > plenty of safety factor designed in as far as series pass transistors, etc. > but the size of the wires was amazingly small. I completely rewired the > high current circuits to match the rest of the design. I am wondering if > during the period of this antique repeater there was a shortage of copper > and the price was high. After rewiring, the power output of the transmitter > was noticeably increased to about 78 watts while it's specified as a 70 watt > PA. I took the repeater to a staging area where we had another duplexer to > test it on the air. (The actual installation is in the county jail in a > jail cell) Distant signals would develop a COR but there was no audio when > using the duplexer. When the antenna is directly attached to the receiver > with the transmitter on dummy load, it works fine. At this point we were > too tired to go further so will get back on it again soon. I suppose the > front end may need touching up with that duplexer which has been checked out > on another setup. > Thanks again to Joe, Larry and the list for their excellent help. > > 73 de > Morris KI4IUA > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
