Re: [Repeater-Builder] Duplexer questions
You do get a 20dB improvement of isolation, this may help if you only have a 4 cavity duplexer.On 2/9/06, Jeff DePolo WN3A < [EMAIL PROTECTED]> wrote:>> Here's a thought -- if you put a isolator between the PA and >> the duplexer,>> and a isolator between the duplexer and the antenna, wouldn't your>> duplexer see a near perfect 50 ohms at all times? >>> The isolator in the output of the duplexer would have to > replace the output> TEE - else you would have 25 plus db of rec loss - REC signal> would go into> the isolator load.ssbAnd even then it wouldn't work, because the receive side of the duplexer (connected where a reject load would normally be) doesn't provide a goodmatch at the Tx frequency, so the isolator ends up providing no isolation(i.e. the isolator will no longer be the ideal 50 ohm virtual load that you were hoping for).--- JeffYahoo! 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/ YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
RE: [Repeater-Builder] Duplexer questions
>> Here's a thought -- if you put a isolator between the PA and >> the duplexer, >> and a isolator between the duplexer and the antenna, wouldn't your >> duplexer see a near perfect 50 ohms at all times? > > > The isolator in the output of the duplexer would have to > replace the output > TEE - else you would have 25 plus db of rec loss - REC signal > would go into > the isolator load.ssb And even then it wouldn't work, because the receive side of the duplexer (connected where a reject load would normally be) doesn't provide a good match at the Tx frequency, so the isolator ends up providing no isolation (i.e. the isolator will no longer be the ideal 50 ohm virtual load that you were hoping for). --- Jeff 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/
RE: [Repeater-Builder] Duplexer questions
At 2/8/2006 19:55, you wrote: > Another viewpoint. > > > > The rating of the cavities by be what you can inject into the duplex system >and still maintain the isolation rating. You may not harm the cavities but I >still stick with what I said earlier. Drop the power to 100 Watts. This or I once tried to TX through a 6-section UHF mobile duplexer (similar to the PD-633-6, rated for 50 watts) with 100 watts. As I turned up the power, the Teflon insulator in the first TX section began to arc at ~80-85 watts. Bob NO6B 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/
RE: [Repeater-Builder] Duplexer questions
Mark, If I may throw my two cents into this. I would not run the power into the cavities more than they are rated for. You could be really looking for problems down the road as Eric said. Look at it this way. You can buy many different tires for say a Corvette. Some of the may be only rated at say 100 MPH and cheaper. The Vet may run 140 - 150. That 100 MPH tire will most likely hold up at 140 or 150 MPH, but do you want to be the one to find out if it would or would not. I would not bet MY life on it. This analogy may be crude but I think that it works. The same goes for the duplexers. I would not be bet the life or my PAs either. Another viewpoint. The rating of the cavities by be what you can inject into the duplex system and still maintain the isolation rating. You may not harm the cavities but I still stick with what I said earlier. Drop the power to 100 Watts. This or see if you can pick up another set of cavities. The ones that I picked up were near new from a local two-way shop and I think are rated at 250 Watts. I think that I gave 250 for them. May have just got lucky but maybe you can also. Just my two cents worth. james// -Original Message- 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/
RE: [Repeater-Builder] Duplexer questions
Thanks, Eric. I'm already doing a search for a new set. Main problem is - I'm not financing the project, the county is...and sometimes I'm not at the top of the priorities list. :-( I have a set rated for 250W picked out in the Tessco catalog, but... Not like Christmas and the old Sears "Wish Book", is it??? BTW - the set I have is from an MSR2000 110W station. Motorola is notorious for under-rating their equipment, so does anyone know whether there is there any headroom on these jugs? And if so, how far can they be expected to "stretch", if at all?? Mark - N9WYS From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric LemmonSent: Wednesday, February 08, 2006 9:55 PMTo: Repeater-Builder@yahoogroups.comSubject: RE: [Repeater-Builder] Duplexer questions Mark, The problem with exceeding the power rating of your duplexer is complex. For starters, the duplexer cans are going to get hot, and this will cause temperature cycling that may cause "pumping" of the tuning rod. This will ultimately cause noise and eventual failure of the transmit cavities. Let's say your duplexer has a 1.5 dB insertion loss, which is more or less typical for a four-cavity BpBr duplexer. 1.5 dB loss equates to about 29% of the signal, so about 44 watts will be dissipated in the duplexer. That may not seem like much, but it quickly builds up. If you have a six-cavity duplexer, with an insertion loss around 2.2 dB, the power lost in the duplexer increases to about 60 watts. Of course, the power is distributed among the two or three cans on the transmit side. The isolator will suck up a small amount of power in the forward direction if it is properly tuned. If I were you, I'd be looking for a duplexer with a power handling capacity at least 25% higher than your PA rating. Choose wisely... 73, Eric Lemmon WB6FLY YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
RE: [Repeater-Builder] Duplexer questions
Mark, The problem with exceeding the power rating of your duplexer is complex. For starters, the duplexer cans are going to get hot, and this will cause temperature cycling that may cause "pumping" of the tuning rod. This will ultimately cause noise and eventual failure of the transmit cavities. Let's say your duplexer has a 1.5 dB insertion loss, which is more or less typical for a four-cavity BpBr duplexer. 1.5 dB loss equates to about 29% of the signal, so about 44 watts will be dissipated in the duplexer. That may not seem like much, but it quickly builds up. If you have a six-cavity duplexer, with an insertion loss around 2.2 dB, the power lost in the duplexer increases to about 60 watts. Of course, the power is distributed among the two or three cans on the transmit side. The isolator will suck up a small amount of power in the forward direction if it is properly tuned. If I were you, I'd be looking for a duplexer with a power handling capacity at least 25% higher than your PA rating. Choose wisely... 73, Eric Lemmon WB6FLY From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of N9WYSSent: Wednesday, February 08, 2006 7:02 PMTo: Repeater-Builder@yahoogroups.comSubject: RE: [Repeater-Builder] Duplexer questions Hi, Eric. Thanks for the insight... I plan on adding a voting receiver system to the machine; in fact, I'm currently working on two of the remotes as I write. (Well, sorta... hehe) I have a Motorola Spectra TAC comparator and 4 receivers, but three of them are on VHF Lo right now. Once converted with UHF receiver sections, they'll be added to the system. So I'm planning on utilizing the wide-area talk-out coverage I have now - and I'm coordinated for that level, so. :-) My next question becomes - how bad can/will I hurt the current cans if I continue operation at this level? Right now, the repeater is not used a whole lot - but that could change as more and more people become aware of its existence. And yes, the first isolator dummy is a 75W unit. Mark - N9WYS From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric LemmonSent: Wednesday, February 08, 2006 7:56 PMTo: Repeater-Builder@yahoogroups.comSubject: RE: [Repeater-Builder] Duplexer questions Mark, Bandpass/Bandreject, also known by the short name "BpBr" is the same as a Bandpass/Notch duplexer. The names are somewhat misleading, because the bandpass effect is relatively modest, although the notch is quite sharp. It is a good idea to have a pure bandpass cavity or two between the duplexer and the receiver, especially if you have a preamplifier. Gee- do you really need 150 watts? If your duplexer is rated at 100 watts, why abuse it with more than its rating? Even with an isolator after the PA, you are definitely looking at grief down the road- maybe in the next block! With so much power, your repeater will likely "talk" much farther than than it "hears." I'd suggest running the PA at 80 watts or so, and make sure that the first load on the isolator is rated at 75 watts or more. Remember, the range of a repeater is *usually* limited by its ability to hear the stations in the field, not by its output power. 73, Eric Lemmon WB6FLY YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
RE: [Repeater-Builder] Duplexer questions
Hi, Eric. Thanks for the insight... I plan on adding a voting receiver system to the machine; in fact, I'm currently working on two of the remotes as I write. (Well, sorta... hehe) I have a Motorola Spectra TAC comparator and 4 receivers, but three of them are on VHF Lo right now. Once converted with UHF receiver sections, they'll be added to the system. So I'm planning on utilizing the wide-area talk-out coverage I have now - and I'm coordinated for that level, so. :-) My next question becomes - how bad can/will I hurt the current cans if I continue operation at this level? Right now, the repeater is not used a whole lot - but that could change as more and more people become aware of its existence. And yes, the first isolator dummy is a 75W unit. Mark - N9WYS From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric LemmonSent: Wednesday, February 08, 2006 7:56 PMTo: Repeater-Builder@yahoogroups.comSubject: RE: [Repeater-Builder] Duplexer questions Mark, Bandpass/Bandreject, also known by the short name "BpBr" is the same as a Bandpass/Notch duplexer. The names are somewhat misleading, because the bandpass effect is relatively modest, although the notch is quite sharp. It is a good idea to have a pure bandpass cavity or two between the duplexer and the receiver, especially if you have a preamplifier. Gee- do you really need 150 watts? If your duplexer is rated at 100 watts, why abuse it with more than its rating? Even with an isolator after the PA, you are definitely looking at grief down the road- maybe in the next block! With so much power, your repeater will likely "talk" much farther than than it "hears." I'd suggest running the PA at 80 watts or so, and make sure that the first load on the isolator is rated at 75 watts or more. Remember, the range of a repeater is *usually* limited by its ability to hear the stations in the field, not by its output power. 73, Eric Lemmon WB6FLY YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
RE: [Repeater-Builder] Duplexer questions
Mark, Bandpass/Bandreject, also known by the short name "BpBr" is the same as a Bandpass/Notch duplexer. The names are somewhat misleading, because the bandpass effect is relatively modest, although the notch is quite sharp. It is a good idea to have a pure bandpass cavity or two between the duplexer and the receiver, especially if you have a preamplifier. Gee- do you really need 150 watts? If your duplexer is rated at 100 watts, why abuse it with more than its rating? Even with an isolator after the PA, you are definitely looking at grief down the road- maybe in the next block! With so much power, your repeater will likely "talk" much farther than than it "hears." I'd suggest running the PA at 80 watts or so, and make sure that the first load on the isolator is rated at 75 watts or more. Remember, the range of a repeater is *usually* limited by its ability to hear the stations in the field, not by its output power. 73, Eric Lemmon WB6FLY From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of N9WYSSent: Tuesday, February 07, 2006 10:03 PMTo: Repeater-Builder@yahoogroups.comSubject: [Repeater-Builder] Duplexer questions Can someone please explain what the difference is between a BandPass/BandReject duplexer and a BandPass/Notch duplexer? Is one more desirable that the other and if so, why? Also - I just put a new PA online today on my 444.550 machine. The duplexer I have is rated at 100W, and the PA is putting about 150W into it -- I was running about 50W with the old PA. (BTW - There is an isolator between the duplexer and the PA.) Will this cause me any grief either now or down the road and if so, in what way?? I'm finally getting the bugs tuned out of this system and I want it to be top-shelf. (Of course!) Thanks in advance! Mark - N9WYS Repeater Trustee - WW9AE repeater (444.550 + PL114.8) YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
RE: [Repeater-Builder] Duplexer questions
> Wouldn't it be fair to say that a notch duplexer rejects only the > 'opposite' frequency in the system while a BandReject duplexer rejects > ANYTHING other than the pass frequency? Umm, a filter that rejects ANYTHING other than the pass frequency is a bandpass filter! -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.15.2/252 - Release Date: 2/6/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.15.2/253 - Release Date: 2/7/2006 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/
RE: [Repeater-Builder] Duplexer questions
The Wacom Products, BpBr duplexer in 2M (wp641) and 70CM (wp678) uses pass tuning with a series capacitor for a notch. The notch is usually set to the opposite TX or RX freq, except when there is adequate isolation and you need to notch a different offending frequency, ie, 2 repeaters sharing a single antenna system. The band reject is actually a notch on a discreet frequency and not the entire band.. NU5D -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of mch Sent: Wednesday, February 08, 2006 2:10 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer questions Wouldn't it be fair to say that a notch duplexer rejects only the 'opposite' frequency in the system while a BandReject duplexer rejects -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.15.2/252 - Release Date: 2/6/2006 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/
RE: [Repeater-Builder] Duplexer questions
The isolator in the output of the duplexer would have to replace the output TEE - else you would have 25 plus db of rec loss - REC signal would go into the isolator load.ssb -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Kris Kirby Sent: Wednesday, February 08, 2006 1:16 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Duplexer questions On Wed, 8 Feb 2006, N9WYS wrote: > running about 50W with the old PA. (BTW - There is an isolator between > the duplexer and the PA.) Will this cause me any grief either now or Here's a thought -- if you put a isolator between the PA and the duplexer, and a isolator between the duplexer and the antenna, wouldn't your duplexer see a near perfect 50 ohms at all times? -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.15.2/252 - Release Date: 2/6/2006 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/
Re: [Repeater-Builder] Duplexer questions
Wouldn't it be fair to say that a notch duplexer rejects only the 'opposite' frequency in the system while a BandReject duplexer rejects ANYTHING other than the pass frequency? (within the limits of the notches) So, a BandReject duplexer will help eliminating mixing products, while a Notch duplexer won't. Given the choice, I would always take a BP-BR duplexer over a notch duplexer. Joe M. Jeff DePolo wrote: > > > Can someone please explain what the difference is between a > > BandPass/BandReject duplexer and a BandPass/Notch duplexer? > > In our little two-way radio world, the answer is that there is no > difference. > > Technically speaking, a "notch" is very narrow, targeting only a specific > frequency. A theoretical definition of a notch might include the phrase > "infinitesimally narrow", but that doesn't exist in the real world - you > can't achive an infinite Q. > > Likewise, as is often seen in other RF endeavors, a "band reject" implies a > wider reject response, not just a single targeted frequency. For example, a > band reject filter used in the TV/CATV world might reject a whole 6 MHz wide > channel, or several contiguous channels. > > But the bottom line is that, in two-way, manufacturers seem to use the two > terms interchangably. So don't lose any sleep over it. > > > Also - I just put a new PA online today on my 444.550 > > machine. The duplexer I have is rated at 100W, and the PA is > > putting about 150W into it -- I was running about 50W with > > the old PA. (BTW - There is an isolator between the duplexer > > and the PA.) Will this cause me any grief either now or down > > the road and if so, in what way?? > > Quite possibly, yes. Duplexers' maximum power rating is usually a function > of one of two factors: either its ability (or lack thereof) to dissipate > heat as a function of insertion loss, or the breakdown voltages of one or > more of its internal components (such as piston trimmer caps or thin > dielectric materials). > > --- Jeff > > > Yahoo! Groups Links > > > > 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/
Re: [Repeater-Builder] Duplexer questions
The isolator between the PA and the duplexer is fine, but the one between the antenna and the duplexer would only work with a 2 antenna repeater. In a single antenna system most of the received signals would end up in the reject load of the isolator between the antenna and the duplexer. If you want real performance the 2 antenna way works well, assuming reasonable antenna separation on the tower. Jack K6YC - Original Message - From: "Kris Kirby" <[EMAIL PROTECTED]> To: Sent: Tuesday, February 07, 2006 11:15 PM Subject: Re: [Repeater-Builder] Duplexer questions > On Wed, 8 Feb 2006, N9WYS wrote: >> running about 50W with the old PA. (BTW - There is an isolator between >> the duplexer and the PA.) Will this cause me any grief either now or > > Here's a thought -- if you put a isolator between the PA and the duplexer, > and a isolator between the duplexer and the antenna, wouldn't your > duplexer see a near perfect 50 ohms at all times? > > I've heard one local ham talk about his theories of repeaters, and he > strongly supports making sure the SWR is as low as possible. I used to > think he's nuts, then I realized there is some truth in that -- at a > minimum SWR, the antenna is as close to matched as possible, even if that > is slightly off frequency. It makes sense to me that if the PA is > expecting a 50-ohm load, and the antenna is 50-ohms, then the SWR will be > 1:1. > > Comments? > > -- > Kris Kirby, KE4AHR <[EMAIL PROTECTED]> > "BIG BROTHER IS WATCHING YOU!" > This message brought to you by the US Department of Homeland Security > > > > > > Yahoo! Groups Links > > > > > > 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/
Re: [Repeater-Builder] Duplexer questions
On Wed, 8 Feb 2006, N9WYS wrote: > running about 50W with the old PA. (BTW - There is an isolator between > the duplexer and the PA.) Will this cause me any grief either now or Here's a thought -- if you put a isolator between the PA and the duplexer, and a isolator between the duplexer and the antenna, wouldn't your duplexer see a near perfect 50 ohms at all times? I've heard one local ham talk about his theories of repeaters, and he strongly supports making sure the SWR is as low as possible. I used to think he's nuts, then I realized there is some truth in that -- at a minimum SWR, the antenna is as close to matched as possible, even if that is slightly off frequency. It makes sense to me that if the PA is expecting a 50-ohm load, and the antenna is 50-ohms, then the SWR will be 1:1. Comments? -- Kris Kirby, KE4AHR <[EMAIL PROTECTED]> "BIG BROTHER IS WATCHING YOU!" This message brought to you by the US Department of Homeland Security 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/
RE: [Repeater-Builder] Duplexer questions
> Can someone please explain what the difference is between a > BandPass/BandReject duplexer and a BandPass/Notch duplexer? In our little two-way radio world, the answer is that there is no difference. Technically speaking, a "notch" is very narrow, targeting only a specific frequency. A theoretical definition of a notch might include the phrase "infinitesimally narrow", but that doesn't exist in the real world - you can't achive an infinite Q. Likewise, as is often seen in other RF endeavors, a "band reject" implies a wider reject response, not just a single targeted frequency. For example, a band reject filter used in the TV/CATV world might reject a whole 6 MHz wide channel, or several contiguous channels. But the bottom line is that, in two-way, manufacturers seem to use the two terms interchangably. So don't lose any sleep over it. > Also - I just put a new PA online today on my 444.550 > machine. The duplexer I have is rated at 100W, and the PA is > putting about 150W into it -- I was running about 50W with > the old PA. (BTW - There is an isolator between the duplexer > and the PA.) Will this cause me any grief either now or down > the road and if so, in what way?? Quite possibly, yes. Duplexers' maximum power rating is usually a function of one of two factors: either its ability (or lack thereof) to dissipate heat as a function of insertion loss, or the breakdown voltages of one or more of its internal components (such as piston trimmer caps or thin dielectric materials). --- Jeff 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/
