[Repeater-Builder] R1225 repeater
A while back I posted an inquiry regarding an R1225 repeater I was looking at for another. it was deaf as a fence post. Well, today I had a chance to finally open this thing up and get a look-see. (This took so long because I've been ridding myself of a number of kidney stones.) Anyway, the front end of the receiver is burnt to a crisp - my best guess is that it got hit with strong incoming RF that was not blocked by a mis-tuned duplexer. or the owner hooked the duplexer up backward. (I think this was discussed previously.) Anyway, in order to get this thing going, I am in need of the receive board layout diagram and a parts list. With the radio oriented so the RX antenna connection is at the lower left, the components that are toasted are just above the antenna connection. (They all look like SMC capacitors, but without the board layout and parts list, I can't be certain - nor can I determine proper replacement values.) If anyone can help, I'd be much obliged! Thanks in advance! Mark - N9WYS n9wys (at) ameritech (dot) net
RE: [Repeater-Builder] R1225 repeater
Mark, You should order a copy of the R1225 service manual 6880905Z53 from Motorola Parts while it is still in print. It costs about $13, less than 1/3 the cost to make a color copy of it. The receiver front end has back-to-back diodes to provide some protection against high voltages, but a lightning strike or a misconnection to a transmitter can certainly fry them. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Thursday, December 27, 2007 2:12 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] R1225 repeater A while back I posted an inquiry regarding an R1225 repeater I was looking at for another. it was deaf as a fence post. Well, today I had a chance to finally open this thing up and get a look-see. (This took so long because I've been ridding myself of a number of kidney stones.) Anyway, the front end of the receiver is burnt to a crisp - my best guess is that it got hit with strong incoming RF that was not blocked by a mis-tuned duplexer. or the owner hooked the duplexer up backward. (I think this was discussed previously.) Anyway, in order to get this thing going, I am in need of the receive board layout diagram and a parts list. With the radio oriented so the RX antenna connection is at the lower left, the components that are toasted are just above the antenna connection. (They all look like SMC capacitors, but without the board layout and parts list, I can't be certain - nor can I determine proper replacement values.) If anyone can help, I'd be much obliged! Thanks in advance! Mark - N9WYS
RE: [Repeater-Builder] R1225 repeater
Thanks Eric. I was kinda hoping that someone had the manual and I could get just the RX board layout and parts list pages... Even at $13, I'd rather not spend the money for a one-time use - but it looks as if that's the way I'm going to have to go. Thanks and Happy New Year, Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Eric Lemmon Mark, You should order a copy of the R1225 service manual 6880905Z53 from Motorola Parts while it is still in print. It costs about $13, less than 1/3 the cost to make a color copy of it. The receiver front end has back-to-back diodes to provide some protection against high voltages, but a lightning strike or a misconnection to a transmitter can certainly fry them. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of n9wys A while back I posted an inquiry regarding an R1225 repeater I was looking at for another. it was deaf as a fence post. Well, today I had a chance to finally open this thing up and get a look-see. (This took so long because I've been ridding myself of a number of kidney stones.) Anyway, the front end of the receiver is burnt to a crisp - my best guess is that it got hit with strong incoming RF that was not blocked by a mis-tuned duplexer. or the owner hooked the duplexer up backward. (I think this was discussed previously.) Anyway, in order to get this thing going, I am in need of the receive board layout diagram and a parts list. With the radio oriented so the RX antenna connection is at the lower left, the components that are toasted are just above the antenna connection. (They all look like SMC capacitors, but without the board layout and parts list, I can't be certain - nor can I determine proper replacement values.) If anyone can help, I'd be much obliged! Thanks in advance! Mark - N9WYS Yahoo! Groups Links
RE: RE: [Repeater-Builder] R1225 Repeater
I'll give this a try, Ron. Thanks! Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright Mark, Some verification of the duplexer tuning can be done with 2 HTs, one with an S meter. Simply use one HT on low power, 0.1 W, transmit thru the duplexer to the other HT with S-meter both tuned to what one wants the notch and again at the pass freqs. You can get some idea if the notch is tuned. Having a good attenuator can aid in this. Also direct HT to HT with attneuator, at least 50 db, for reference could be used. I've used this for tuning duplexers although not the preferred method. With the going back and forth with this issue at least one can get some sort of handle on the tuning of the duplexer. If you have better equipment use it, but sounds as if you do not and the dual HT approach will give you something. 73, ron, n9ee/r ps do not wish to drive directly the .1 W into the HT for receive obviously.
Re: [Repeater-Builder] R1225 Repeater
What I have done to Rough it in is use a low power watt meter (mine is 4 watts) and a HT or mobile rig. You can at least see if you are way out before you connect an HT to receive. Brian ka9pmm n9wys wrote: I'll give this a try, Ron. Thanks! Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com On Behalf Of Ron Wright Mark, Some verification of the duplexer tuning can be done with 2 HTs, one with an S meter. Simply use one HT on low power, 0.1 W, transmit thru the duplexer to the other HT with S-meter both tuned to what one wants the notch and again at the pass freqs. You can get some idea if the notch is tuned. Having a good attenuator can aid in this. Also direct HT to HT with attneuator, at least 50 db, for reference could be used. I've used this for tuning duplexers although not the preferred method. With the going back and forth with this issue at least one can get some sort of handle on the tuning of the duplexer. If you have better equipment use it, but sounds as if you do not and the dual HT approach will give you something. 73, ron, n9ee/r ps do not wish to drive directly the .1 W into the HT for receive obviously.
RE: [Repeater-Builder] R1225 Repeater
Good idea, Ryan! Thanks! FWIW - this has been shelved for the time being, due to the severe winter WX (i.e. ice storm) in the area.. Once the weather is better, I'll get back to work on it. But for now, I need to devote time to my volunteer efforts with the county EMA. Thanks all! Mark - N9WYS _ From: Repeater-Builder@yahoogroups.com On Behalf Of Brian What I have done to Rough it in is use a low power watt meter (mine is 4 watts) and a HT or mobile rig. You can at least see if you are way out before you connect an HT to receive. Brian ka9pmm n9wys wrote: I'll give this a try, Ron. Thanks! Mark - N9WYS -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of Ron Wright Mark, Some verification of the duplexer tuning can be done with 2 HTs, one with an S meter. Simply use one HT on low power, 0.1 W, transmit thru the duplexer to the other HT with S-meter both tuned to what one wants the notch and again at the pass freqs. You can get some idea if the notch is tuned. Having a good attenuator can aid in this. Also direct HT to HT with attneuator, at least 50 db, for reference could be used. I've used this for tuning duplexers although not the preferred method. With the going back and forth with this issue at least one can get some sort of handle on the tuning of the duplexer. If you have better equipment use it, but sounds as if you do not and the dual HT approach will give you something. 73, ron, n9ee/r ps do not wish to drive directly the .1 W into the HT for receive obviously.
FW: [Repeater-Builder] R1225 Repeater
Sorry - I got the name wrong. I meant to type Brian!! Mark - N9WYS _ From: n9wys [mailto:[EMAIL PROTECTED] Good idea, Ryan! Thanks! FWIW - this has been shelved for the time being, due to the severe winter WX (i.e. ice storm) in the area.. Once the weather is better, I'll get back to work on it. But for now, I need to devote time to my volunteer efforts with the county EMA. Thanks all! Mark - N9WYS _ From: Repeater-Builder@yahoogroups.com On Behalf Of Brian What I have done to Rough it in is use a low power watt meter (mine is 4 watts) and a HT or mobile rig. You can at least see if you are way out before you connect an HT to receive. Brian ka9pmm n9wys wrote: I'll give this a try, Ron. Thanks! Mark - N9WYS -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of Ron Wright Mark, Some verification of the duplexer tuning can be done with 2 HTs, one with an S meter. Simply use one HT on low power, 0.1 W, transmit thru the duplexer to the other HT with S-meter both tuned to what one wants the notch and again at the pass freqs. You can get some idea if the notch is tuned. Having a good attenuator can aid in this. Also direct HT to HT with attneuator, at least 50 db, for reference could be used. I've used this for tuning duplexers although not the preferred method. With the going back and forth with this issue at least one can get some sort of handle on the tuning of the duplexer. If you have better equipment use it, but sounds as if you do not and the dual HT approach will give you something. 73, ron, n9ee/r ps do not wish to drive directly the .1 W into the HT for receive obviously.
RE: [Repeater-Builder] R1225 Repeater
As far as having the coaxes switched, we marked the cables before disassembling the duplexer for re-tuning. However, I do wonder if the guy tuned the notch to the same freq on both sides. I don't recall seeing him change the freq on the monitor while he was tuning the duplexers last night. _ From: Repeater-Builder@yahoogroups.com On Behalf Of Albert Well let us know how it turns out. Hopefully you didn't make the easy mistake of having the coaxes off of the RX and the TX connected to the incorrect ports on the duplexer??? OR maybe the fellow whom tuned the duplexer transposed the high and low sides??? easily enough done and a very easy mistake to make! Albert
Re: [Repeater-Builder] R1225 Repeater
Have you taken the duplexer out of the equation, put a dummy load on the TX port, a tuned antenna on the receive port and see if the receiver is receiving properly? If you have a service monitor, check to see if it is within performance specs for 12db sinad and 20 db quieting. If it is, then it's a duplexer problem. If not, then it's a receiver problem and not a duplexer. Got to first isolate where the trouble is. That would be a very deaf receiver that's either tuned off frequency, shorted coax, busted connectors or other problems. If it's a duplexer, it's tuned wrong and / or highly desensed. Let us know how you make out finding out which component is the culprit. Albert n9wys wrote: A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk... Thanks in advance, Mark - N9WYS
Re: [Repeater-Builder] R1225 Repeater
Well let us know how it turns out. Hopefully you didn't make the easy mistake of having the coaxes off of the RX and the TX connected to the incorrect ports on the duplexer??? OR maybe the fellow whom tuned the duplexer transposed the high and low sides??? easily enough done and a very easy mistake to make! Albert n9wys wrote: I just brought the repeater back to my shack this afternoon... the service monitor test will be one of the first performed. Although I did not tune the duplexers personally, I trust the guy who did tune them - and he did two of them for us. So if it is a bad duplexer, it's actually TWO of them. Thanks for the tips - and now I'm of to the shack and a service monitor. ;-) 73 de Mark - N9WYS From: Repeater-Builder@yahoogroups.com On Behalf Of Albert Have you taken the duplexer out of the equation, put a dummy load on the TX port, a tuned antenna on the receive port and see if the receiver is receiving properly? If you have a service monitor, check to see if it is within performance specs for 12db sinad and 20 db quieting. If it is, then it's a duplexer problem. If not, then it's a receiver problem and not a duplexer. Got to first isolate where the trouble is. That would be a very deaf receiver that's either tuned off frequency, shorted coax, busted connectors or other problems. If it's a duplexer, it's tuned wrong and / or highly desensed. Let us know how you make out finding out which component is the culprit. Albert n9wys wrote: A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk... Thanks in advance, Mark - N9WYS
RE: [Repeater-Builder] R1225 Repeater
I just brought the repeater back to my shack this afternoon. the service monitor test will be one of the first performed. Although I did not tune the duplexers personally, I trust the guy who did tune them - and he did two of them for us. So if it is a bad duplexer, it's actually TWO of them. Thanks for the tips - and now I'm of to the shack and a service monitor. ;-) 73 de Mark - N9WYS _ From: Repeater-Builder@yahoogroups.com On Behalf Of Albert Have you taken the duplexer out of the equation, put a dummy load on the TX port, a tuned antenna on the receive port and see if the receiver is receiving properly? If you have a service monitor, check to see if it is within performance specs for 12db sinad and 20 db quieting. If it is, then it's a duplexer problem. If not, then it's a receiver problem and not a duplexer. Got to first isolate where the trouble is. That would be a very deaf receiver that's either tuned off frequency, shorted coax, busted connectors or other problems. If it's a duplexer, it's tuned wrong and / or highly desensed. Let us know how you make out finding out which component is the culprit. Albert n9wys wrote: A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk. Thanks in advance, Mark - N9WYS
RE: [Repeater-Builder] R1225 Repeater
Mark, Are we talking about the R1225 transceiver itself, or is the repeater actually a GR1225, RKR1225, or a GR400 or GR500 X-Pand repeater? If one of the latter, the duplexer is usually a mobile notch duplexer with six helical resonators in a one-inch-thick package. Does your R1225 repeater use such a duplexer, or is it a full-size BpBr unit with large cavity filters? When a service tech works mostly with BpBr cavities, it is a common error to tune the screws for the pass frequency instead of the notch frequency. A local hospital had a GR1225 repeater come back from a radio shop with the TX and RX cables reversed, and it wouldn't work very well. It tested fine on the service monitor, but the tech got confused about the HIGH and LOW labels on the notch duplexer. The ports should have been labeled REJECT HIGH and REJECT LOW, with the former going to the TX output on the R1225 and the latter going to the RX input on the R1225. If the R1225 is a high-power (25-50 watt) model, it is possible that operating the transceiver with a mis-tuned notch duplexer can burn out the protection diodes in the RX front end. There is no tune-up required on the R1225. The RX front end is varactor-tuned by the CPU to optimize the RX sensitivity. The R1225 service manual is 6880905Z53, about $13, and is a must-have document. If your repeater is a GR1225, you also need the 6880904Z90 manual, also about $13. If your repeater is an RKR1225, you also need the 6880907Z10 manual, about $36. Finally, if your repeater is a GR400/GR500 X-Pand model, you also need the 6880905Z54 manual, about $13. Many early GR1225 repeaters were shipped with a duplexer harness made of RG58 single-shielded cable. I was setting up one such GR1225 on a VHF repeater pair with a 5.26 MHz split, and I was measuring almost 12 dB of desense. I cured the problem completely by making up a new harness using RG-400/U double-silver-shielded cable and the proper connectors on the ends- no adapters. That repeater is still in service after three years with no down time, but is being replaced with a new MTR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Thursday, November 29, 2007 4:02 PM To: [EMAIL PROTECTED]; Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] R1225 Repeater A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk. Thanks in advance, Mark - N9WYS
RE: [Repeater-Builder] R1225 Repeater
Hi Eric. The machine I have is as you described as the latter - it employs a mobile-type, 6-resonator notch duplexer. It is on 452/457 MHz. As for the exact model designation, it says Radius GR1225 on the front panel... We've tried reversing the cables going to the duplexer, with no change in performance... I labeled the cables myself when we disassembled the unit to have the duplexer retuned, so I know which one was supposed to go where. I'm seriously beginning to think the duplexer is erroneously tuned to notch the RX freq on both sides. So in essence, there is no high and low notch, there is just high. Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Eric Lemmon Mark, Are we talking about the R1225 transceiver itself, or is the repeater actually a GR1225, RKR1225, or a GR400 or GR500 X-Pand repeater? If one of the latter, the duplexer is usually a mobile notch duplexer with six helical resonators in a one-inch-thick package. Does your R1225 repeater use such a duplexer, or is it a full-size BpBr unit with large cavity filters? When a service tech works mostly with BpBr cavities, it is a common error to tune the screws for the pass frequency instead of the notch frequency. A local hospital had a GR1225 repeater come back from a radio shop with the TX and RX cables reversed, and it wouldn't work very well. It tested fine on the service monitor, but the tech got confused about the HIGH and LOW labels on the notch duplexer. The ports should have been labeled REJECT HIGH and REJECT LOW, with the former going to the TX output on the R1225 and the latter going to the RX input on the R1225. If the R1225 is a high-power (25-50 watt) model, it is possible that operating the transceiver with a mis-tuned notch duplexer can burn out the protection diodes in the RX front end. There is no tune-up required on the R1225. The RX front end is varactor-tuned by the CPU to optimize the RX sensitivity. The R1225 service manual is 6880905Z53, about $13, and is a must-have document. If your repeater is a GR1225, you also need the 6880904Z90 manual, also about $13. If your repeater is an RKR1225, you also need the 6880907Z10 manual, about $36. Finally, if your repeater is a GR400/GR500 X-Pand model, you also need the 6880905Z54 manual, about $13. Many early GR1225 repeaters were shipped with a duplexer harness made of RG58 single-shielded cable. I was setting up one such GR1225 on a VHF repeater pair with a 5.26 MHz split, and I was measuring almost 12 dB of desense. I cured the problem completely by making up a new harness using RG-400/U double-silver-shielded cable and the proper connectors on the ends- no adapters. That repeater is still in service after three years with no down time, but is being replaced with a new MTR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of n9wys A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk. Thanks in advance, Mark - N9WYS
RE: [Repeater-Builder] R1225 Repeater
If this is the case, you may have steered full transmit power into the receiver. The results would not be good. Keith McQueen 801-224-9460 [EMAIL PROTECTED] -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Thursday, November 29, 2007 9:55 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] R1225 Repeater Hi Eric. The machine I have is as you described as the latter - it employs a mobile-type, 6-resonator notch duplexer. It is on 452/457 MHz. As for the exact model designation, it says Radius GR1225 on the front panel... We've tried reversing the cables going to the duplexer, with no change in performance... I labeled the cables myself when we disassembled the unit to have the duplexer retuned, so I know which one was supposed to go where. I'm seriously beginning to think the duplexer is erroneously tuned to notch the RX freq on both sides. So in essence, there is no high and low notch, there is just high. Mark - N9WYS -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of Eric Lemmon Mark, Are we talking about the R1225 transceiver itself, or is the repeater actually a GR1225, RKR1225, or a GR400 or GR500 X-Pand repeater? If one of the latter, the duplexer is usually a mobile notch duplexer with six helical resonators in a one-inch-thick package. Does your R1225 repeater use such a duplexer, or is it a full-size BpBr unit with large cavity filters? When a service tech works mostly with BpBr cavities, it is a common error to tune the screws for the pass frequency instead of the notch frequency. A local hospital had a GR1225 repeater come back from a radio shop with the TX and RX cables reversed, and it wouldn't work very well. It tested fine on the service monitor, but the tech got confused about the HIGH and LOW labels on the notch duplexer. The ports should have been labeled REJECT HIGH and REJECT LOW, with the former going to the TX output on the R1225 and the latter going to the RX input on the R1225. If the R1225 is a high-power (25-50 watt) model, it is possible that operating the transceiver with a mis-tuned notch duplexer can burn out the protection diodes in the RX front end. There is no tune-up required on the R1225. The RX front end is varactor-tuned by the CPU to optimize the RX sensitivity. The R1225 service manual is 6880905Z53, about $13, and is a must-have document. If your repeater is a GR1225, you also need the 6880904Z90 manual, also about $13. If your repeater is an RKR1225, you also need the 6880907Z10 manual, about $36. Finally, if your repeater is a GR400/GR500 X-Pand model, you also need the 6880905Z54 manual, about $13. Many early GR1225 repeaters were shipped with a duplexer harness made of RG58 single-shielded cable. I was setting up one such GR1225 on a VHF repeater pair with a 5.26 MHz split, and I was measuring almost 12 dB of desense. I cured the problem completely by making up a new harness using RG-400/U double-silver-shielded cable and the proper connectors on the ends- no adapters. That repeater is still in service after three years with no down time, but is being replaced with a new MTR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com On Behalf Of n9wys A friend of mine has a Motorola R1225 repeater that is as deaf as a fence post. We've tried re-tuning the original duplexer and replacing it with another known-good duplexer. We even tried separating the antennas, although we could only get about 30' of vertical separation between the two. Nothing seems to work - and at 150mW on an HT, I can only get about 30' away from the repeater antenna before I cannot access it. 4W will give me a range of about 100 yds. Does anyone have the manual for this machine? If so, I'd be much obliged for a copy of any receiver tune-up procedures. I hate to think this thing is junk. Thanks in advance, Mark - N9WYS
[Repeater-Builder] R1225 Repeater Exciter Output??????
Hi all I am New to the group and wonting to know if anyone knows the output power of a Motorola R1225 Repeater?? the reason I wont to know this is i have an Amp thats driven with 200 to 300MW and am trying to figure out how to get the power output down to that if at all posable. 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] R1225 Repeater Exciter Output??????
I believe these repeaters are based on the MaxTrac/Radius/M1225 product line; as such they probably output 25 or 45 watts. You would need to use the radio service software to turn the output power down, however it will be unstable and quite inefficient at such a low level. The power won't remain where you set it, and the output signal may contain spurious signals that aren't allowed to be there. You could turn the output power down to about 1/4 of the rated output and it would likely operate properly. That still gets you down to 6-10 watts. Depending on who made the power amp you wish to use, it might be possible to have it reconfigured to utilize 5-10 watts of input drive (I did that with a Henry UHF amplifier by sending it back to them). Then you could use the amp with the R1225, assuming the duplexer will also handle the additional output power. Unless you're going for a LOT of power, you probably won't notice much of an improvement with an external amp. Moving from 45 watts to 90 watts is a 3dB gain, and that's barely noticeable. Even going up to 180 watts is only 6dB. You really need 10dB of gain to make enough improvement at the user radios, and that's almost 500 watts! Bob M. == --- ag4uw [EMAIL PROTECTED] wrote: Hi all I am New to the group and wonting to know if anyone knows the output power of a Motorola R1225 Repeater?? the reason I wont to know this is i have an Amp thats driven with 200 to 300MW and am trying to figure out how to get the power output down to that if at all posable. __ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com 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] R1225 Repeater Exciter Output
It depends upon which one of the four models of the R1225 you have. Here they are: M03GRC90C2AA, 146-174 MHz, adjustable 1 to 10 watts M43GRC90C2AA, 146-174 MHz, adjustable 25 to 50 watts M04GRC90C2AA, 444-474 MHz, adjustable 1 to 10 watts M44GRC90C2AA, 444-474 MHz, adjustable 25-45 watts The two 10 watt models of the R1225 repeater were created primarily to be used with the Radius 100 watt repeater package, where the output feeds a TPL 100 watt power amplifier. The 45/50 watt models are found in GR1225, RKR1225, and GR500 repeater packages. As I mentioned in a previous posting on this same topic, you can adjust the output of one of the 10 watt models down to 2.5 watts, and use a 10 dB 5 watt power attenuator to give you 250 mW for driving your PA. 73, Eric Lemmon WB6FLY ag4uw wrote: Hi all. I am new to the group and want to know if anyone knows the output power of a Motorola R1225 Repeater. The reason I want to know this is I have an amp that's driven with 200 to 300mW and am trying to figure out how to get the power output down to that, if at all possible. 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/
