Tom, Thanks for going into detail about the symptoms and your actions to date. This is instructive and very useful to all readers of this list.
A few things came to light as I reviewed your findings and the information about what modules are in your stations. I see that both stations have 110 watt intermittent-duty PAs that are specified to operate over the 146-174 MHz range. However, the TFD6102A harmonic filter that is in both stations is specified for 150.8-174 MHz. Although you can retune this filter per Kevin's procedure on the RBTIP, try to find the TFD6101A filter if you want to operate on 2m; it specs at 132-150.8 MHz. The base station appears to have an oddball receiver. The GSB-B station should have a TRD6302A receiver, which is an unfiltered 10.7 MHz IF unit. Perhaps some tech put a TRD6182 fully-filtered unit in its place to correct a desense problem. You'd be surprised how many folks forget that this one filter can cause a low power output problem. In addition to having a lot of filtering components on the interconnect boards and in the duplex exciter, the repeater stations also have extra shielding plates. Even though some may pooh-pooh the idea, those plates should be installed with all screws in place for maximum shielding effectiveness. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of tomnevue Sent: Monday, April 23, 2007 10:48 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Need VHF MSR2000 Repeater help Thanks for all the input. I have some information now and I hope I'll have the rest tomorrow. Repeater was at 155Mhz with a 700Khz split. It was fully operational at the time of removal, due to 800Mhz upgrade about 5 years ago. The Units were stored in an airconditioned/heated environment and were not touched my anyone until I received it. I confirmed that the repeater was fully operational before doing any Ham conversion. I did this by operating into a dummy load and using 2 HT's that were part of this system. 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. 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. 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. 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. The jumper cables from the repeater cabinet to the Duplexer is Milspec RG400 and no adapters are used. I tuned both units the same way (for the same frequency). For the exciter, I pre-adjusted the coils the amount estimated by the graphs from the starting freq (155 MHz). The final adjustment is 147.120/147.720MHz. I built a test meter and followed the step by step instructions to tune the RF circuits. I netted the crystal. I did not make any adjustment to the modulation at this point. I did make receiver / repeater audio level comparisons and the 2 are very close. I did not make any adjustments to the PA except to turn down the power to 50 watts. The 2M power out was approximately the same as it was at 155MHz. I tuned both receivers by presetting the coils the appropriate amount from the starting frequency of 155MHz. Then again I followed the tune up procedures in the manual. The signal source was a well shielded low power HT into a dummy load. The starting points for tuning both the receiver and transmitter were very close to the final settings. I am testing the 2 repeaters by swapping 1 set of receive/transmit elements. 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, the repeater randomly hangs and sometimes makes a loud growl sound when dropped. With the transmitter turned down to about 4 watts (into the Duplexer) or 50 watts into a dummy load (at the cabinet) the receiver sensitivity is about what I expected (receives weak signals). So, it's a fine operating 4 watt repeater. I tested the 2 units with a 3rd unmodified SG card and had the same problem. Tomorrow I'll put a different transmitter and receiver thru the duplexer and see if the receiver experiences desensing. Of course these will not be connected as a repeater. I guess after that I'll have to see if I can get help from someone with a spectrum analyzer or station monitor. Have I missed anything?? MODEL NUMBERS: Repeater - C73GSB3105AT, Transmitter ABZ89FC3632, Receiver ABZ89FR3633, Receive unit TRD6182APR, Exciter TLD9242C, PA TLD2532A Base - C73GSB3105B, Transmitter ABZ89FC3632, Receiver ABZ89FR3633, Receive unit TRD6182A, Exciter TLD9232B, PA TLD2532A Tom W2MN
