Perhaps the last update on the SCT1000/SCR200 rebuild: We took the duplexer that we had been using for testing back to the guy who tuned it. It turns out that it was tuned for another repeater frequency so we were ok with the setup of the repeater itself. Thanks to Larry and Joe specifically and to the list in general for all your good assistance and appropriate questions. The repeater should soon be back on task.
73 de Morris KI4IUA > -----Original Message----- > From: Morris Dillingham [mailto:mdi...@nnwifi.com] > Sent: Tuesday, March 17, 2009 6:54 PM > To: 'k1ike_m...@snet.net' > Cc: 'Repeater-Builder@yahoogroups.com' > Subject: RE: [Repeater-Builder] SCR-200(A) > > Continuing saga of the SCR-1000 which received signals that keyed COR but > with no received audio: > > We tested again today with the transmitter inhibited but using the > duplexer. Receiver performed fine up to 5 or more miles away. Apparently > the duplexer is questionably aligned and is causing desense. We go on > Saturday to the original tuner who is expressing doubts about how he > originally tuned the duplexer. He has spectrum analyzer and other > equipment which will allow checking for spurs, etc. so it's not all that > bad that this happened, especially since I learned so much about the > importance of separation of signals. > > 73 de > Morris KI4IUA > > > > > -----Original Message----- > > From: Morris Dillingham [mailto:mdi...@nnwifi.com] > > Sent: Friday, March 13, 2009 10:34 PM > > To: 'k1ike_m...@snet.net' > > Cc: 'Repeater-Builder@yahoogroups.com' > > Subject: RE: [Repeater-Builder] SCR-200(A) > > > > Joe, the duplexer had been tuned by someone else. It did appear to work > > ok in another lashup with other equipment. I haven't been back to the > > test site to try it without the transmitter but it could have been > desense > > as the COR worked. I'll have to get my cohort to try it as he is close > to > > the equipment in fact it's at his QTH. You may have guessed by now that > > I'm new to this facet of radio. I'm beginning to realize how important > > this desense topic is. Thanks for the great question you pose. We plan > > another test tomorrow with the transmitter off. > > > > > > 73 de > > Morris KI4IUA > > > > > > > > > -----Original Message----- > > > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > > > buil...@yahoogroups.com] On Behalf Of Joe > > > Sent: Friday, March 13, 2009 9:39 PM > > > To: Repeater-Builder@yahoogroups.com > > > Subject: Re: [Repeater-Builder] SCR-200(A) > > > > > > 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 > > > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > >
