[DSTAR_DIGITAL] 2 meters and desense
Hello Group, Has anyone run into this problem with the RP2000V repeater: at 25 watts i have the worst desense that I've seen in many years, I've owned and built many repeaters over the years for my-self and many groups but this is the worst, with a 4 can duplexer's and a pass cavity i still have major issues I'm wondering if anyone else has had this issue and what were the fixes Tony NN1D Trustee for K1RFI
[DSTAR_DIGITAL] Re: 2 meters and desense
This link may be helpful. Your mileage may very. http://www.bosshardradio.com/dstarrepeatertesting/dstarrepeatertesting.htm --- In dstar_digital@yahoogroups.com, Radioman radioma...@... wrote: Hello Group, Has anyone run into this problem with the RP2000V repeater: at 25 watts i have the worst desense that I've seen in many years, I've
Re: [DSTAR_DIGITAL] 2 meters and desense
well to start with the outside signal is garbled up until i switch to low then the user clears up, when switching back to hi he gets garbled up again and when the user unkeys i here 2 seconds of robotic noise, and the robotic noise does not happen on low. i think that clear enough desense, with the tracking gen i have 86db of isolation in the 4 pack cans not perfect, but really not bad i also use a 10'' 3foot high band pass cavity set to 1 db of loss and it gives me aprox 20db at 500khz window on my rx freqency honestly i don't think you could ask for any better then that, but the desense sounds like i have no duplexer's and I'm starting to point at the poor construction of this over sized empty box and shielding mobile radios give you Tony NN1D
[DSTAR_DIGITAL] RS-RP2C Software needed
Hi Group, We are busy setting up a new D-Star system in Curacao, Caribbean. Due to a frequency issue, we had to exchange some items with Icom. During this process, the CDROM with the drivers and config software got 'misplaced'. Can anybody help me with a copy/email or FTP site where I can download the Drivers and config so I can finish the install? Thanks! 73 de Brett PJ2BR Keeper of PJ2A Repeater
RE: [DSTAR_DIGITAL] 2 meters and desense
honestly i don't think you could ask for any better then that, but the desense sounds like i have no duplexer's and I'm starting to point at the poor construction of this over sized empty box and shielding mobile radios give you Hmm, well there are many ‘poor construction over sized empty box’ units running just fine out there. I didn’t replace the cables on mine, just brought it up and began testing. We used a handheld with a fixed antenna with switchable attenuators. We continued to drop the signal coming out of the handheld until we started get packet errors. Then we added a 20dB preamp that allowed us to drop the input signal another 9dB until we started getting packet errors. We then switched to low power and were not able to really find a difference. Next test was to put a dummy load on the transmitter which didn’t make any noticeable difference, so we assumed very little if any desense. 73
Re: [DSTAR_DIGITAL] 2 meters and desense
ya, thats a nice way to test it out... i'll try the patch cables first, then work from there but at this point you can see my frustration.. Tony NN1D
Re: [DSTAR_DIGITAL] 2 meters and desense
On Nov 27, 2009, at 10:09 AM, Radioman wrote: Has anyone run into this problem with the RP2000V repeater: at 25 watts i have the worst desense that I've seen in many years, I've owned and built many repeaters over the years for my-self and many groups but this is the worst, with a 4 can duplexer's and a pass cavity i still have major issues I'm wondering if anyone else has had this issue and what were the fixes Tony NN1D Trustee for K1RFI I'm sure someone has. ;-) What does it do on a dummy load directly? How about a dummy load AFTER the cans but before it goes up the tower? In other words, have you done your homework to find out if the desense is really desense, or possibly an external mix or something plastering your receiver with out-of-band (or in-band) signals? Is the desense in the building or outside? What kind of interconnect cabling are you using to the duplexer? What kind of cabling out of the duplexer up the tower/to the antenna? There were some people who replaced the INTERNAL cable jumpers from the mobile rigs hiding inside the module, to the rear N-connectors, but that problem (I thought) was mostly limited to the UHF modules... the cable used inside the modules isn't high-quality double-shielded cabling... as if Icom has zero idea how to build a REPEATER... But I haven't heard of anyone who MEASURED and CONFIRMED they had an internal (to the module) desense problem on VHF. Generally, the receivers are too broad/non-selective, but have decent sensitivity. From various reports, some folks have successfully utilized low-gain pre-amplifiers only after doing massive filtering for out-of-band signals, and the performance goes up a bit (hard to measure in dB, since this is digital... in fact, a bit hard to measure AT ALL, but relative performance measurements still work, like on any RF system)... others have found their site noise on their chosen frequencies to be too high to utilize them. And almost everyone I've talked to with wicked-good performance is filtering the receiver more than a typical Band-pass/Band-reject 4-can duplexer... especially at VHF. That duplexer is probably right on the edge of being enough isolation. What (specific) duplexer is it? What's your duplexer rated for for isolation numbers in dB? Since it's REALLY hard to measure performance on these things compared to analog FM, where there's plenty of high-quality test gear floating around, and a simple SINAD measurement tells the tale of whether or not your receive side of the system is working properly, you need to shoot for a LOT of isolation in the design... a belt an suspenders approach of a duplexer and a High-Q bandpass cavity really isn't a bad idea... along with PERFECT highly shielded RF cabling, but you'd have to describe (in excruciating detail) your entire setup, to get it right via e-mail from afar... This concept is no different than any other repeater, it's just more important with D-STAR because of the lack of a good way to measure performance. Repeater builders get away with a lot on analog FM repeaters because you can still pick the person out of the noise if performance isn't what it's supposed to be, by the numbers. Thus, D-STAR repeaters require a bit more engineering thought and design of the RF side, up-front... or you sit and scratch your head wondering What's wrong?. Real-world examples: Our VHF module here is definitely the weaker-performer over the UHF, but there's a bunch of reasons for that including a requirement that we use a combined antenna system with some budgetary constraints on how the antenna is shared, the fact that the only open pair was 145.25 which is avoided like the plague by analog FM folks because of CATV leakage, and more. It's about as good as it's going to get, but our UHF outperforms the VHF. And both underperform the best analog FM repeater at the same site on the same antennas... if you're looking for perfect copy including the non-error-corrected DV low-speed data. We still get 80+ miles of voice coverage on both, but the low-speed data is often gobledeegook for low-power (HT) users who are mobile and/or not line-of-sight to the antennas, and once in a while HT user's audio garbles with some on-site intermittent interference, and/or CATV noise (can't easily tell which) on VHF. 1.2 GHz on the other hand, I hear is ROCK SOLID, using the very nice TX/TX duplexer/combiner setup they offer for D-STAR 1.2 GHz data/voice mixed modules that a local ham donated by spending the big bucks. It was a priority because no one wanted to use the triple frequency trick and try to do it with UHF cavities, for sure... which HAS been done successfully on analog FM 1.2 GHz repeaters in the local area in the past and present. Someone also popped for a VERY nice directional panel/corner reflector style antenna from W6OAL at Ye Olde Antenna Labs in Parker, CO for the 1.2 GHz system. Another analog FM
Re: [DSTAR_DIGITAL] 2 meters and desense
Well At least I'm not alone I presume I have the same problem, and I didn't relize I needed 90 plus isolation, so I'll swap out the 4 pack for the 6 pack I have and check things out, did u swap out the internal jumpers? Thanks for the reply and better news! 73 - Tony Sent from my iPod On Nov 27, 2009, at 5:19 PM, Allan Boyd ve3...@vianet.ca wrote: Greetings Tony; Well after reading your e-mail let me know you are not alone with this problem with desense with the Icom D-Star 2 meter repeater. Our D-Star machine had the exact same problem when we first put it on the air. We had a 4 can duplexer with a high band pass cavity that was operating on a 60 watt analog repeater (GE Master II) with no problem at all. Once we put the D-star machine up on the same frequency same antenna and duplexer, cables etc the only thing that changed was the repeater was desense to the hilt. Tests showed we had about 85 db isolation. Like you we tried many things and troubleshooted everything else knowing that the duplexers were good. After much head scratching we finally learned through Icom rep that the D-Star Icom IR-RP2000V needs at least a minimum of 90db isolation and I say 90db at the very least. We finally changed out the 4 can to a 6 can Sinclair res lock duplexer with a 100 db isolation and all I can say is WOW what a difference. The desense disappeared and the D-Star repeater now way out preformed the analog repeater we had up, it works amazingly because of the extra isolation. As you are aware the front ends of the Icom machine are not the best and leave a lot to be desired we learned the rule with this model repeater the more isolation you have the better you are. It worked fine for the analog system with the GE master II however once we went digital we needed the new set of cans up from 4 to six. Now I am not saying that this may be your problem but by your e-mail it certainly sounded like my complaint earlier in the year. Good luck. 73 Al VE3AJB Trustee VE3RXR Stack Ontario Canada At 01:26 PM 27/11/2009, Radioman wrote: well to start with the outside signal is garbled up until i switch to low then the user clears up, when switching back to hi he gets garbled up again and when the user unkeys i here 2 seconds of robotic noise, and the robotic noise does not happen on low. i think that clear enough desense, with the tracking gen i have 86db of isolation in the 4 pack cans not perfect, but really not bad i also use a 10'' 3foot high band pass cavity set to 1 db of loss and it gives me aprox 20db at 500khz window on my rx freqency honestly i don't think you could ask for any better then that, but the desense sounds like i have no duplexer's and I'm starting to point at the poor construction of this over sized empty box and shielding mobile radios give you Tony NN1D
Re: [DSTAR_DIGITAL] 2 meters and desense
Hi Tony; I think you will find that this may be the problem as I could have swore that the old duplexers were enough to do it. As for the jumpers yes we purchased brand new double shielded RG-142 with new N connectors between the repeater band pass filter and duplexers just to make sure. Like I said it is like night and day for us. Hope it works the same please keep us updated. Thanks Al VE3AJB At 07:33 PM 27/11/2009, Radioman wrote: Well At least I'm not alone I presume I have the same problem, and I didn't relize I needed 90 plus isolation, so I'll swap out the 4 pack for the 6 pack I have and check things out, did u swap out the internal jumpers? Thanks for the reply and better news! 73 - Tony Sent from my iPod On Nov 27, 2009, at 5:19 PM, Allan Boyd mailto:ve3...@vianet.cave3...@vianet.ca wrote: Greetings Tony; Well after reading your e-mail let me know you are not alone with this problem with desense with the Icom D-Star 2 meter repeater. Our D-Star machine had the exact same problem when we first put it on the air. We had a 4 can duplexer with a high band pass cavity that was operating on a 60 watt analog repeater (GE Master II) with no problem at all. Once we put the D-star machine up on the same frequency same antenna and duplexer, cables etc the only thing that changed was the repeater was desense to the hilt. Tests showed we had about 85 db isolation. Like you we tried many things and troubleshooted everything else knowing that the duplexers were good. After much head scratching we finally learned through Icom rep that the D-Star Icom IR-RP2000V needs at least a minimum of 90db isolation and I say 90db at the very least. We finally changed out the 4 can to a 6 can Sinclair res lock duplexer with a 100 db isolation and all I can say is WOW what a difference. The desense disappeared and the D-Star repeater now way out preformed the analog repeater we had up, it works amazingly because of the extra isolation. As you are aware the front ends of the Icom machine are not the best and leave a lot to be desired we learned the rule with this model repeater the more isolation you have the better you are. It worked fine for the analog system with the GE master II however once we went digital we needed the new set of cans up from 4 to six. Now I am not saying that this may be your problem but by your e-mail it certainly sounded like my complaint earlier in the year. Good luck. 73 Al VE3AJB Trustee VE3RXR Stack Ontario Canada At 01:26 PM 27/11/2009, Radioman wrote: well to start with the outside signal is garbled up until i switch to low then the user clears up, when switching back to hi he gets garbled up again and when the user unkeys i here 2 seconds of robotic noise, and the robotic noise does not happen on low. i think that clear enough desense, with the tracking gen i have 86db of isolation in the 4 pack cans not perfect, but really not bad i also use a 10'' 3foot high band pass cavity set to 1 db of loss and it gives me aprox 20db at 500khz window on my rx freqency honestly i don't think you could ask for any better then that, but the desense sounds like i have no duplexer's and I'm starting to point at the poor construction of this over sized empty box and shielding mobile radios give you Tony NN1D
Re: [DSTAR_DIGITAL] 2 meters and desense
Shanon, I'm fwding this for info. On Nov 27, 2009, at 5:19 PM, Allan Boyd ve3...@vianet.ca mailto:ve3...@vianet.ca wrote: Greetings Tony; Well after reading your e-mail let me know you are not alone with this problem with desense with the Icom D-Star 2 meter repeater. Our D-Star machine had the exact same problem when we first put it on the air. We had a 4 can duplexer with a high band pass cavity that was operating on a 60 watt analog repeater (GE Master II) with no problem at all. Once we put the D-star machine up on the same frequency same antenna and duplexer, cables etc the only thing that changed was the repeater was desense to the hilt. Tests showed we had about 85 db isolation. Like you we tried many things and troubleshooted everything else knowing that the duplexers were good. After much head scratching we finally learned through Icom rep that the D-Star Icom IR-RP2000V needs at least a minimum of 90db isolation and I say 90db at the very least. We finally changed out the 4 can to a 6 can Sinclair res lock duplexer with a 100 db isolation and all I can say is WOW what a difference. The desense disappeared and the D-Star repeater now way out preformed the analog repeater we had up, it works amazingly because of the extra isolation. As you are aware the front ends of the Icom machine are not the best and leave a lot to be desired we learned the rule with this model repeater the more isolation you have the better you are. It worked fine for the analog system with the GE master II however once we went digital we needed the new set of cans up from 4 to six. Now I am not saying that this may be your problem but by your e-mail it certainly sounded like my complaint earlier in the year. Good luck. 73 Al VE3AJB Trustee VE3RXR Stack Ontario Canada At 01:26 PM 27/11/2009, Radioman wrote: well to start with the outside signal is garbled up until i switch to low then the user clears up, when switching back to hi he gets garbled up again and when the user unkeys i here 2 seconds of robotic noise, and the robotic noise does not happen on low. i think that clear enough desense, with the tracking gen i have 86db of isolation in the 4 pack cans not perfect, but really not bad i also use a 10'' 3foot high band pass cavity set to 1 db of loss and it gives me aprox 20db at 500khz window on my rx freqency honestly i don't think you could ask for any better then that, but the desense sounds like i have no duplexer's and I'm starting to point at the poor construction of this over sized empty box and shielding mobile radios give you Tony NN1D
