> "tomnevue" <[EMAIL PROTECTED]> wrote: > Thanks for all the input. I have some information now > and I hope I'll have the rest tomorrow.
Great... "you've got questions..? We've got answers..." Where have I heard that before? [major text edit (for sanity)] > Repeater was at 155Mhz with a 700Khz split. I confirmed that the > repeater was fully operational before doing any Ham conversion. excellente' > I did this by operating into a dummy load and using 2 HT's that > were part of this system. Well... not the test I had in mind but what the heck. Onward... > The only thing done to the repeater for Ham conversion was > retuning, moving the configuration jumpers needed and > modifying the Squelch Gate card per Skipps article. All internal > cabling is exactly as supplied by Motorola. He's a trouble maker... I know him well. > The Sinclair Q202 (4 can) duplexer was aligned in a laboratory by > someone who has experience doing this; notch slightly better than > 90dB. This exciter has the added backplane filter plug assembly. Per my previous post... I'd park the duplexer and service only the repeater until you find the problems. You also mention going from an original 700KHz repeater offset to an Amateur (2 meter band) 600KHz offset. Are you using the same duplexer? > The base unit was at approximately 155Mhz also. I moved jumpers as > needed to look like the repeater. I got another SG card and made the > same modification. You should keep one Squelch Gate Module Stock until you get one repeater station working as normal. Just keeps your sanity to have a known original/standard for benchmark testing. > The Rec / Trans cables are the same cables supplied by Motorola > with TR switch removed and bulkhead connectors added. So, the Base > looks just like the original repeater. No it is not..! There are a number of different tr relay cables used and they don't full duplex well without some bit of caution. Is your rx cable a small white only cable direct to the output jack and is that jack cable connection sealed 100% with a rear mounted SO-239 jack "coax hood"? The PA output cable should be Brown RG-393/400U or similar type teflon coaxial cable. Unless you have the luxury of some semi small rigid coax (hard line) you can use. If you're using the white relay coax in the repeater tx line... part of your problem is leakage to & from the small white coax. > The jumper cables from the repeater cabinet to the Duplexer is > Milspec RG400 and no adapters are used. Ahhh....! TAKE THE LMR-400 COAX AND THROW IT AWAY! Replace it with some RG-214 (mil spec type). One item to note... If you were testing all this with just the repeater first (no duplexer per my post). You would not have to worry about the LMR-400 hosing up the works until you later confirmed the repeater is working normally. Once again... TAKE THE LMR-400 COAX AND THROW IT IN THE TRASH! > I pre-adjusted the coils the amount estimated by the graphs excellente' > I built a test meter and followed the step by step instructions > to tune the RF circuits. I really don't what to mess up a good thing... but the metering point values displayed by the original 50uA meter movement (test box) will actually be slightly different from the same test point when using a Multi Meter. Just something to know... > I netted the crystal. Smell like fish? just kidding... > I did not make any adjustment to the modulation at this point. If the repeater has the original ctcss "pl" module/card in place you need only confirm the transmit ctcss level is about 700KHz and you can consider the tx channel element IDC value is pretty close to where it should be for normal voice operation. > The starting points for tuning both the receiver and > transmitter were very close to the final settings. Should be... although some of the metering point dips and peaks are really, really small in value. You have to be watching the test point meter locations with a quality meter and a bright light to make sure you reach the right coil positions/locations. > When the transmitter power is turned up above 4 watts into either > a separate antenna or the duplexer or combinations of duplexer > separate antennas the receiver is badly desensed, You should have the pa output parked into a termination (load) for most all this early testing. > the repeater randomly hangs and sometimes makes a loud growl > sound when dropped. "doesn't know the words" > I tested the 2 units with a 3rd unmodified SG card and had > the same problem. Helps isolate the mod as being a source of the problem(s). > Have I missed anything?? Yeah... a bit. Trash the LMR-400 Cable. Per my first post... take the repeater pa output direct from the pa to your termination/load for testing. also get rid of (replace) the hacked and soldered tr/relay coax cables. Make 100% sure your cabinet side mounted SO-239 jacks have the proper rear mounted hoods (shields). ... that is if you end up even using the original internal cable paths. Sometimes it's worth doing something different. ... and make sure the cabinet internal (and external for that matter) coax cable paths have as much separation as possible'. Buy some RG-214 mil spec version coax cable for the duplexer cables and a bottle of Petite Sirah to help with the operator lubrication. ... and club the person who gave/sold you the LMR-400. cheers, s.
