[Repeater-Builder] Re: Notching nearby frequencies
Ian, What you would like to do is not difficult just may be expensive if you do not have the filters you would need. You described your situation as you want to receive on 479.350 and you have a link transmitter on 481.825 on the same or nearby antenna. As the 481.825 is a link transmitter you may have better luck putting a Notch filter on the output of the 481.825 that would notch the 479.350 signal away from 481.825. You could stand to loose a few DB on the transmit unless you have a broad notch filter which would mean you may need more than one to tighten your notch in favor of 479.350 and allow more pass of the 481.825. This may mean more insertion loss for the 481 transmit so as long as you can stand to loose the signal then that should adjust the interfering frequency better. As a note you can use Pass as long as there is enough of it and these get expensive. Jason --- In Repeater-Builder@yahoogroups.com, "Kerincom" wrote: > > Hi guys .Can you clarify something for me .I have a repeater that receives > on 479.350 and has a link transmitter on 481.825 and I would like to filter > the 481.825 out so it doesn't affect the 479.350. I currently have between > the diplexer and the 479.350 receiver -a band pass cavity tuned to 479.350 > and a notch diplexer tuned to notch the 481.825 . > I am concerned that this is reducing the receiver sensitivity and feel I > would be better to have the band pass between the diplexer and receiver and > using a t piece connect the notch to the t piece > Current setup Diplexer--band pass cavitynotch diplexerreceiver > > Proposed setup Diplexer -- band pass cavity ---t piece receiver > >Notch > I will try the proposed setup shortly on on a hp service monitor to see if I > am better this way > > Thank You, > Ian Wells, > Kerinvale Comaudio, > 361 Camboon Road.Biloela.4715 > Phone 0749922574 or 0409159932 > www.kerinvalecomaudio.com.au >
[Repeater-Builder] Re: DB4060 Duplexer Cables
Good Evening Mike, I'm afraid I agree with Eric, The problems you are experiencing are not common, when you stated you moved the crystals from the Mark 4 to the spare and are experiencing the same result, was this with the same set of cans? If it was then try two mobiles on the same set of cans and check for desense that way eliminating the Mark 4 and any other Xtal rig you are using. If your desense is still there after the mobile test then you need a tracking generator to go with your spectrum analyser. That will be a start in "seeing" where your problem may lie. Anything more than that may be a return loss bridge and do a resonance check of the entire duplexer. If you do not have the access to the equipment, you can always try a seperate antenna on the opposite port for the duplexer to determine which side, i.e. Rx or Tx is the issue. If you have disassembled the cans and are not having much luck then the Tracking generator should show you where they are tuned and if they are really giving you a problem. By the way, what was your Sinad reading on the Rx of the Mark 4. If you are having more problems with noise than signal you may have found this in your earlier test when you swapped the Xtals and found their amplifier stage may be giving you the grief. If you swapped the Xtal in the element, versus sending it to a crystal house for overhaul, then a cold solder joint makes for all kinds of Rx fun in the form of noise. I am not 100% on the Mark 4, but if it has an Rx alignment procedure, run through that while chasing the Rx board with cold spray or a gentle tap during the test and see if your sinad changes or your performance changes. Your 8920 will show you that in the right range if you have a problem as you look at you Tx signal I hope this can help, Jason --- In Repeater-Builder@yahoogroups.com, "Mike Besemer \(WM4B\)" <[EMAIL PROTECTED]> wrote: > > I spent the weekend working on a set of DB4060 cans (cleaning and retuning) > and have managed to commit the ultimate stupidity. I had all the harnesses > off and instead of MARKING them I just laid them out on the bench. > Unfortunately, the bench got 'cleaned' and the cables are now all mixed up. > > > I can tell which 2 cables went between the cans and which went to the > T-connector, but all 4-cables are different lengths. I assume that the > shorter of the two cables go on the TX (high) side of the cans and the > shorter go on the RX (low) side of the cans. Am I correct? > > Thanks for the help. next time I'll mark the cables! > > 73, > > Mike > WM4B >
[Repeater-Builder] Re: Motorola XPR 8300 - Mototrbo Repeater
Can anyone say Telario? or Privacy Plus? Try using one of those products for an Amateur repeater and I'll give you $1.00. Just about as useful. The product is stretching the limits of being a supportable product. It fits the other profiles of new radios where in this case without a Service monitor that does TDMA, you cannot align to 6.25 Khz and see or hear that the unit is to spec's. Just another name for D-STAR except this is being launched commercially first. Jason --- In Repeater-Builder@yahoogroups.com, Gary <[EMAIL PROTECTED]> wrote: > > That's up to two active channels on one frequency pair. I find the built in > controller works fine as a stand alone repeater in either the digital or > analog mode. Even CWID is built in. I agree though that they offer little or > no interfacing but that may change. > Gary > > Bill Powell wrote: > > > The current MTBO repeaters are pretty much useless except as plain old > > repeaters: they (currently) have NO audio-level (or other) interface > > at all. This is my BIG objection to using them in Public Safety apps: > > no console level access. And, as to having the dispatchers access > > the repeater via a radio - no thanks. > > > > OTOH, the local M dealer has been making noises that M will be adding > > a whole raft of features - RSN. Remember: M + Options = > > > > Don't forget: MTBO is a TDMA system w/ 2 "channels" in each box, > > requiring 2 controllers and a hat full of magic rabbits. > > > > Good luck though, > > Bill - WB1GOT > > > > --- In Repeater-Builder@yahoogroups.com, "Tony L." > > wrote: > > > > > > Any members of this User Group have one of these in service yet? > > > > > > Curious to know if interfacing it to an external controller is possible > > > without pulling your hair out (as is the case with the MTR2000's). > > > > > > Thanks. > > > > > > > > > Yahoo! Groups Links > > > > > > >
