[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 >
Re: [Repeater-Builder] Re: DB4060 Duplexer Cables
Skip's comment is right on the mark. I was tuning several old Sinclair Q202G VHF duplexers a couple of years ago and when I pulled a couple of cavities apart to see the difference between the low pass side and the high pass side, I found none. They were exactly the same. Turned out that the coax stub from the can to the Tee connector was part of the tuned circuit for the notch. A dielectric capacitor with a delron tuning rod to tune the notch was in parallel with the coax leaving the cavity. I was moving the duplexer from 170 mHz to 146 mHz and had to lengthen the coax from the cavity to the Tee to get the notch to tune. In addition, someone on the list here clued me in to the fact that this type of notch tuning produces a notch above AND below the cavity resonant frequency. That was an eye opener. And that was the reason I could find no difference in the construction between the high side and the low side of these particular duplexers. 73 - Jim W5ZIT --- On Mon, 10/6/08, skipp025 <[EMAIL PROTECTED]> wrote: From: skipp025 <[EMAIL PROTECTED]> Subject: [Repeater-Builder] Re: DB4060 Duplexer Cables To: Repeater-Builder@yahoogroups.com Date: Monday, October 6, 2008, 11:38 AM In many examples you might also find coax stubs from the T Connector to the top of the cavity coax port, which also modifies the typical BPBR response. cheers, s. ,___
RE: [Repeater-Builder] RE: DB4060 Duplexer Cables
Thanks Paul... that helps. I found some pictures I took of the old setup... should be able to get the cables back where they belong from them. I always assumed they were the same too... stupid me! I'll be marking them this time! 73, Mike WM4B > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of Paul N1BUG > Sent: Monday, October 06, 2008 7:11 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] RE: DB4060 Duplexer Cables > > Mike Besemer (WM4B) wrote: > > And as a follow up to my first question, as I understand it. there > > should be no problem with swapping the TX and RX cans (and retuning > > them), correct? > > That's correct for the DB4060 since the cans, coupling loops and > notch capacitors are all the same. > > But it's not true for all cavities/duplexers. Some are designed to > have the notch on one side of the pass only, where a specific can is > either high pass or low pass but not the other. Actually even then > it's more a matter of the coupling loops and/or notch tuning parts > being different, not the actual cans themselves. > > I can't help with the cable length question. When I had my DB4062 (6 > can version) apart I marked the cables. BUT, looking at them I > thought they were all the same length. I didn't attempt to measure > them since I was afraid straightening them to do that would put > undue strain on them. > > Paul N1BUG > > > > > > Yahoo! Groups Links > > >
[Repeater-Builder] Re: DB4060 Duplexer Cables
In many examples you might also find coax stubs from the T Connector to the top of the cavity coax port, which also modifies the typical BPBR response. cheers, s. : it's more a matter of the coupling loops and/or notch : tuning parts being different, not the actual cans themselves. > Paul N1BUG <[EMAIL PROTECTED]> wrote: > > That's correct for the DB4060 since the cans, coupling loops and > notch capacitors are all the same. > > But it's not true for all cavities/duplexers. Some are designed to > have the notch on one side of the pass only, where a specific can is > either high pass or low pass but not the other. Actually even then > it's more a matter of the coupling loops and/or notch tuning parts > being different, not the actual cans themselves. > > I can't help with the cable length question. When I had my DB4062 (6 > can version) apart I marked the cables. BUT, looking at them I > thought they were all the same length. I didn't attempt to measure > them since I was afraid straightening them to do that would put > undue strain on them. > > Paul N1BUG > > > Mike Besemer (WM4B) wrote: > > And as a follow up to my first question, as I understand > > it there should be no problem with swapping the TX and > > RX cans (and retuning them), correct?
Re: [Repeater-Builder] RE: DB4060 Duplexer Cables
Mike Besemer (WM4B) wrote: > And as a follow up to my first question, as I understand it… there > should be no problem with swapping the TX and RX cans (and retuning > them), correct? That's correct for the DB4060 since the cans, coupling loops and notch capacitors are all the same. But it's not true for all cavities/duplexers. Some are designed to have the notch on one side of the pass only, where a specific can is either high pass or low pass but not the other. Actually even then it's more a matter of the coupling loops and/or notch tuning parts being different, not the actual cans themselves. I can't help with the cable length question. When I had my DB4062 (6 can version) apart I marked the cables. BUT, looking at them I thought they were all the same length. I didn't attempt to measure them since I was afraid straightening them to do that would put undue strain on them. Paul N1BUG Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
RE: [Repeater-Builder] RE: DB4060 Duplexer Cables
Eric, I've run them on a spectrum analyzer as I have them installed now (TX and RX swapped from original conjuration) and they still seem to pass just fine. maybe a dB or so of loss. Based on that, I think I'm okay. agreed? All I need to do is figure out which cable goes where! Mike _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Sunday, October 05, 2008 10:25 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] RE: DB4060 Duplexer Cables Mike, Not necessarily! Some duplexers are asymmetrical, meaning that one "side" is intended for pass low and notch high, while the other is for pass high and notch low. When the manufacturer puts "TX" and "RX" labels on the connectors, it leads some folk to invert the tuning- often leading to grief. It doesn't matter to the duplexer which side is TX or RX; it works either way. In some parts of California, as well as in a few other states, repeaters have a low-input, high-output repeater split which is the opposite of conventional practice. That's why it is better to identify which side passes low and which passes high. Use a spectrum analyzer to determine which cans pass low and which pass high, and mark them accordingly. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com [mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com] On Behalf Of Mike Besemer (WM4B) Sent: Sunday, October 05, 2008 6:52 PM To: 'Mike Besemer (WM4B)'; Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com Subject: [Repeater-Builder] RE: DB4060 Duplexer Cables And as a follow up to my first question, as I understand it. there should be no problem with swapping the TX and RX cans (and retuning them), correct? Mike WM4B _ From: Mike Besemer (WM4B) [mailto:[EMAIL PROTECTED] <mailto:mwbesemer%40cox.net> net <mailto:[EMAIL PROTECTED] <mailto:mwbesemer%40cox.net> net> ] Sent: Sunday, October 05, 2008 9:10 PM To: 'Repeater-Builder@ <mailto:%27Repeater-Builder%40yahoogroups.com> yahoogroups.com' Subject: DB4060 Duplexer Cables 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
RE: [Repeater-Builder] RE: DB4060 Duplexer Cables
Mike, Not necessarily! Some duplexers are asymmetrical, meaning that one "side" is intended for pass low and notch high, while the other is for pass high and notch low. When the manufacturer puts "TX" and "RX" labels on the connectors, it leads some folk to invert the tuning- often leading to grief. It doesn't matter to the duplexer which side is TX or RX; it works either way. In some parts of California, as well as in a few other states, repeaters have a low-input, high-output repeater split which is the opposite of conventional practice. That's why it is better to identify which side passes low and which passes high. Use a spectrum analyzer to determine which cans pass low and which pass high, and mark them accordingly. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mike Besemer (WM4B) Sent: Sunday, October 05, 2008 6:52 PM To: 'Mike Besemer (WM4B)'; Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] RE: DB4060 Duplexer Cables And as a follow up to my first question, as I understand it. there should be no problem with swapping the TX and RX cans (and retuning them), correct? Mike WM4B _ From: Mike Besemer (WM4B) [mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> ] Sent: Sunday, October 05, 2008 9:10 PM To: 'Repeater-Builder@yahoogroups.com' Subject: DB4060 Duplexer Cables 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: DB4060 Duplexer Cables
And as a follow up to my first question, as I understand it. there should be no problem with swapping the TX and RX cans (and retuning them), correct? Mike WM4B _ From: Mike Besemer (WM4B) [mailto:[EMAIL PROTECTED] Sent: Sunday, October 05, 2008 9:10 PM To: 'Repeater-Builder@yahoogroups.com' Subject: DB4060 Duplexer Cables 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
