Alexander, Motorola makes a preamp for their T43-T83 Mitreks that is inserted after some filtering on the front end. May be a better way to implement a rx preamp in your setup, and they're pretty cheap, bought a few recently for $25/each. Also, I agree with Glenn that separating the Mitrek decks into separate receive and transmit rather than doing the duplex mod is a much better approach for 2M on the Mitrek.
John/N4SJW --- In [email protected], "Alexander Tubonjic" <[EMAIL PROTECTED]> wrote: > Hello, > Well here is one that cant be figured out locally, thought I would > throw it to the experts. My high school radio club has recently made a > few upgrades to our VHF repeater. We replaced the Ringo Ranger antenna > with a Comet GP-9 Antenna, replaced the 9913 coax with Andrews 1/2'' > Heliax, and put a Mirage Pream inline. The problem we are having is > mainly with the preamp (I think) > I will describe the setup and give all the specs first. The repeater > Rx and Tx is from a 110 Watt Motorola Mitrek power out from the Mitrek > is 50 watts. The power supply is an Astron RS-70M, Duplexer is a > Sinclair Q202G (yes, it is properly tuned and working as it should) > the antenna is rooftop on the schools theater building (the roof is > about 75 feet AGL and the antenna is on an 8' mast pipe) there are no > obstructions for at least 5 miles around. The preamp setup is as > follows, it is after the duplexers and before the reciever. We have > the preamp directly connected into the duplexer and a jumper going > from the preamp to the Rx bulkhead on the repeater cabinet. The preamp > has two settings, a higher gain and a lower gain setting, initially we > had it setup to the higher gain setting but I went up today and > switched over to lower gain and turned the power output to 30 watts. > The problem we have is the Rx is not what is should be. It is a tad > worse then when we were running the repeater at 15 watts without the > Preamp. I would really like to get the preamp to work like it should > in the repeater system, I just dont have any ideas on what to do next > to get better sensitivity on the machine. Any thoughts and ideas would > be appreciated. Thanks. > Alexander KG4OGN > > P.s, all jumpers are made with double shielded ridgid coax, so thats > not the cause of the problem. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
