RE: [Repeater-Builder] Ge mastr 2 link question
Thanks for all of the suggestions. However I think you guys are missing the problem. Both repeaters work fine when they are not linked together. As stand alone machines they work fine and the audio sounds fine. Once I turn on the secondary port on the NHRC-4/m2 is when the noise occurs. Do you hear the hum on both repeater Tx's, or just the slaved repeater? And does it matter which Rx the user comes in on when the hum is heard? I took a quick look at the NHRC-4 schematic. One thing I see is that they use polarized caps on the Tx audio outputs. The op-amp that drives those outputs is centered at half the supply voltage (i.e. about 6.9 VDC in a 13.8V world). The polarization of the caps is with the + toward the op amp. If you're driving the mic hi line in a Mastr II, it's going to have DC on it to power the stock mic element. You should lift the resistor that supplies DC bias on the exciter; you don't want the voltage from the radio to be higher than the 6.9V on the other side of the cap. Maybe you mentioned it and I didn't catch it, but are you feeding discriminator (vol-sq hi) audio to the controller, or something else? Are you using PL? If so, how/where are you filtering it, and how/where are you encoding it? Do you have speakers hooked up to the M2's? If so, do you hear hum when there's receiver activity? If you physically disconnect the PTT line from one of the transmitters so that it can't transmit, do you still hear hum? --- Jeff
RE: [Repeater-Builder] Ge mastr 2 link question
Thanks for all of the suggestions. However I think you guys are missing the problem. Both repeaters work fine when they are not linked together. As stand alone machines they work fine and the audio sounds fine. Once I turn on the secondary port on the NHRC-4/m2 is when the noise occurs. I'm thinking it has something to do with the way the controller is handling the audio. Playing with the deviation changes the level of the noise however doesn't get rid of it. The testing is being done on the bench and not at the site. Both machines have been test on bench running alone and work fine. I guess if it was easy it would be fun! Any new suggestions? Thanks, Mike KA2NDW
Re: [Repeater-Builder] Ge mastr 2 link question
Mike DeWaele wrote: Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. I saw (and agree with) the grounding comments made by others. Ground loops suck. Been there, done that. Also double-check that the audio itself doesn't have any component of the received CTCSS left on it coming from each rig before it goes into the NHRC controller. Also consider using shielded cabling between the radios and the controller and tying the shield ground to one end or the other. (We like to use mini teflon coax for our audio connections -- we've been at a few high-RF broadcast sites where the RF would rectify in audio amplifiers in the rigs or controllers and make a mess. Standardizing on mini-coax clears up the problem everywhere in our systems.) Look at the hum on an oscilloscope or similar and see if it's really 60 Hz. That'll help you determine if it's power/grounding related, or coming from something else. Keep hunting. You'll find it... Nate WY0X
RE: [Repeater-Builder] Ge mastr 2 link question
At 10/20/2008 07:21, you wrote: Thanks for all of the suggestions. However I think you guys are missing the problem. Both repeaters work fine when they are not linked together. As stand alone machines they work fine and the audio sounds fine. Once I turn on the secondary port on the NHRC-4/m2 is when the noise occurs. Do you hear the hum on both repeater Tx's, or just the slaved repeater? And does it matter which Rx the user comes in on when the hum is heard? I took a quick look at the NHRC-4 schematic. One thing I see is that they use polarized caps on the Tx audio outputs. The op-amp that drives those outputs is centered at half the supply voltage (i.e. about 6.9 VDC in a 13.8V world). The polarization of the caps is with the + toward the op amp. If you're driving the mic hi line in a Mastr II, it's going to have DC on it to power the stock mic element. You should lift the resistor that supplies DC bias on the exciter; you don't want the voltage from the radio to be higher than the 6.9V on the other side of the cap. If it's had +12V applied to its audio output for some time, it's possible the capacitor is already damaged. I have an NHRC-micro that's had nearly half of the chip capacitors replaced due to failure. The last one shorted vaporized a supply trace as well as a small part of the circuit board itself. Oddly enough, the output coupling cap is still OK, but the 12V mic bias was removed from the MVP before the controller was installled. BTW, while we're talking about coupling capacitors, Digikey has some really tiny non-polarized ceramic capacitors up to 47 µF @ 16 V: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=445-2905-ND. I've used the 10 µF value of the same capacitor series for squashing some nasty EMI problems at work. Their ESR is way lower than standard electrolytics, they were able to totally knock out power supply noise that the electrolytics didn't even touch. Do you have speakers hooked up to the M2's? If so, do you hear hum when there's receiver activity? ...but if you DON'T have speakers connected, have you terminated the speaker outputs into 4 or 8 ohm power resistors? I've seen Mastr II audio PAs go bonkers when those outputs aren't terminated. I usually disable the entire audio PA by cutting off it's A+ supply so the termination is no longer necessary (I never use the speaker output). Bob NO6B
RE: [Repeater-Builder] Ge mastr 2 link question
Do you have speakers hooked up to the M2's? If so, do you hear hum when there's receiver activity? ...but if you DON'T have speakers connected, have you terminated the speaker outputs into 4 or 8 ohm power resistors? I've seen Mastr II audio PAs go bonkers when those outputs aren't terminated. I usually disable the entire audio PA by cutting off it's A+ supply so the termination is no longer necessary (I never use the speaker output). Doh! Forgot to mention that, been bitten by that one too. There's also a noticible (measurable anyway) increase in distortion on the receive audio (VSH) when the speaker is on, and gets worse as you go louder as you might imagine, even when properly loaded. --- Jeff
[Repeater-Builder] Ge mastr 2 link question
Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has a humming noise that almost sounds like it is being over driven. We have adjusted levels on both the controller and discrimators in both radios to no avail. We do have a common ground between both radios per the instructions with the controller. I'm thinking there is smething that needs to be padded in the audio lines. I'm researching the web but if any one has gone before me with the same project I was hoping to save some time. Thanks, Mike KA2NDW
RE: [Repeater-Builder] Ge mastr 2 link question
Mike, Using two separate power supplies might be part of the problem, especially if they are not on the same power phase. Many Astron power supplies have the negative terminal grounded to the chassis, which can allow AC hum to ride on the DC output. If the hum you hear is 120 Hz, that is usually caused by a full-wave rectifier's ripple. If 60 Hz, it is usually a grounding issue. The first thing I would try is to substitute a fully charged lead-acid or gell-cell battery for each Astron power supply, to see if the hum remains. Do not ground any of the negative leads when you perform this test. If this problem occurs at a commercial site, it usually is caused by a power neutral being grounded in a sub-panel by a poorly-trained technician. Besides being a violation of the National Electrical Code, such a condition will almost always result in AC currents flowing in the grounding system- a no-no. When audio circuits are connected into the grounding system, some current will flow through the cable shields and be induced into the audio chain. If the hum goes away when on batteries, try clipping the ground jumper from the negative terminal, inside each Astron power supply. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mike DeWaele Sent: Sunday, October 19, 2008 12:30 PM To: Repeater-Builder Subject: [Repeater-Builder] Ge mastr 2 link question Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has a humming noise that almost sounds like it is being over driven. We have adjusted levels on both the controller and discrimators in both radios to no avail. We do have a common ground between both radios per the instructions with the controller. I'm thinking there is smething that needs to be padded in the audio lines. I'm researching the web but if any one has gone before me with the same project I was hoping to save some time. Thanks, Mike KA2NDW
Re: [Repeater-Builder] Ge mastr 2 link question
Ditto the possible issue with the Astrons, but you may also have too many common grounds. If you have the grounds of the machines interconnected through (1) the power supplies, (2) antenna and/or feedline bonds, (3) rack rails, (4) through the linking cable and (5) an additional, just to be sure ground strap between the radios, you could very easily have a ground loop. Since all the interconnections are made using unbalanced audio lines, you can't just lift the ground at one end as we might try in the pro audio world. Sometimes, a cheapo audio transformer, like the 600-ohm isolation transformers from Radio Shack, are enough to alleviate the loop, because they allow you to leave an audio ground floating from the chassis at one end of the link cable. A quick, cheap investigative tool here is one of the old three-into-two-prong AC plug adapters. If you use it to lift the ground pin on one of the Astrons and the problem goes away, it will be an important clue. Good luck! 73, Paul, AE4KR - Original Message - From: Mike DeWaele To: Repeater-Builder Sent: Sunday, October 19, 2008 1:30 PM Subject: [Repeater-Builder] Ge mastr 2 link question Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has a humming noise that almost sounds like it is being over driven. We have adjusted levels on both the controller and discrimators in both radios to no avail. We do have a common ground between both radios per the instructions with the controller. I'm thinking there is smething that needs to be padded in the audio lines. I'm researching the web but if any one has gone before me with the same project I was hoping to save some time. Thanks, Mike KA2NDW
RE: [Repeater-Builder] Ge mastr 2 link question
Paul, Eric Thanks for the response. I did some more testing with your suggestions. I tried hooking both radios up to a deep cycle battery. The hum is still there so I think that rules out the astrons! The audio from the main repeater to the link isn't as bad as from the link back to the main repeater. Both have a hum to them however the 2 meter to the 440 you can hear the voice. the other way all you get is the hum. For testing I have it on the bench in the basement. the only common connection is only the audio and tx lines between the two radios. I have also tried it with a common ground as suggested by NHRC in the controller directions. Both have the same results. I want to make sure it works here before it goes back to the hill. At the site it's just my radio equipment and Wifi internet which has not given me any problems with both machines working there prior to bringing them to my house to work on this linking project. Maybe tomorrow I will give NHRC a call and see if they have run into this problem before. Thanks, Mike KA2NDW -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Paul Plack Sent: Sunday, October 19, 2008 4:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Ge mastr 2 link question Ditto the possible issue with the Astrons, but you may also have too many common grounds. If you have the grounds of the machines interconnected through (1) the power supplies, (2) antenna and/or feedline bonds, (3) rack rails, (4) through the linking cable and (5) an additional, just to be sure ground strap between the radios, you could very easily have a ground loop. Since all the interconnections are made using unbalanced audio lines, you can't just lift the ground at one end as we might try in the pro audio world. Sometimes, a cheapo audio transformer, like the 600-ohm isolation transformers from Radio Shack, are enough to alleviate the loop, because they allow you to leave an audio ground floating from the chassis at one end of the link cable. A quick, cheap investigative tool here is one of the old three-into-two-prong AC plug adapters. If you use it to lift the ground pin on one of the Astrons and the problem goes away, it will be an important clue. Good luck! 73, Paul, AE4KR - Original Message - From: Mike DeWaele To: Repeater-Builder Sent: Sunday, October 19, 2008 1:30 PM Subject: [Repeater-Builder] Ge mastr 2 link question Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has a humming noise that almost sounds like it is being over driven. We have adjusted levels on both the controller and discrimators in both radios to no avail. We do have a common ground between both radios per the instructions with the controller. I'm thinking there is smething that needs to be padded in the audio lines. I'm researching the web but if any one has gone before me with the same project I was hoping to save some time. Thanks, Mike KA2NDW
RE: [Repeater-Builder] Ge mastr 2 link question
Mike, If the repeater system was working fine, but suddenly got hum without any action on your part, I'd start looking for a failed bypass capacitor. Try turning off AC power to the facility at the main breaker while the repeater is on battery, and see if the hum goes away. Sometimes, an arrestor on the high-voltage (usually 12,000 volts) side of the utility transformer will fail, causing a current to flow through the grounding system. This can cause dangerous voltages to appear on the neutral and grounding conductors, and will cause hum to suddenly appear in sensitive circuits. What frequency is the hum? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mike DeWaele Sent: Sunday, October 19, 2008 5:29 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Ge mastr 2 link question Paul, Eric Thanks for the response. I did some more testing with your suggestions. I tried hooking both radios up to a deep cycle battery. The hum is still there so I think that rules out the astrons! The audio from the main repeater to the link isn't as bad as from the link back to the main repeater. Both have a hum to them however the 2 meter to the 440 you can hear the voice. the other way all you get is the hum. For testing I have it on the bench in the basement. the only common connection is only the audio and tx lines between the two radios. I have also tried it with a common ground as suggested by NHRC in the controller directions. Both have the same results. I want to make sure it works here before it goes back to the hill. At the site it's just my radio equipment and Wifi internet which has not given me any problems with both machines working there prior to bringing them to my house to work on this linking project. Maybe tomorrow I will give NHRC a call and see if they have run into this problem before. Thanks, Mike KA2NDW -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Paul Plack Sent: Sunday, October 19, 2008 4:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Ge mastr 2 link question Ditto the possible issue with the Astrons, but you may also have too many common grounds. If you have the grounds of the machines interconnected through (1) the power supplies, (2) antenna and/or feedline bonds, (3) rack rails, (4) through the linking cable and (5) an additional, just to be sure ground strap between the radios, you could very easily have a ground loop. Since all the interconnections are made using unbalanced audio lines, you can't just lift the ground at one end as we might try in the pro audio world. Sometimes, a cheapo audio transformer, like the 600-ohm isolation transformers from Radio Shack, are enough to alleviate the loop, because they allow you to leave an audio ground floating from the chassis at one end of the link cable. A quick, cheap investigative tool here is one of the old three-into-two-prong AC plug adapters. If you use it to lift the ground pin on one of the Astrons and the problem goes away, it will be an important clue. Good luck! 73, Paul, AE4KR - Original Message - From: Mike DeWaele mailto:[EMAIL PROTECTED] To: Repeater-Builder mailto:Repeater-Builder@yahoogroups.com Sent: Sunday, October 19, 2008 1:30 PM Subject: [Repeater-Builder] Ge mastr 2 link question Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has
Re: [Repeater-Builder] Ge mastr 2 link question
Mike, Although I don't have an NHRC, I've encountered this problem once before with another system. Look at all of your capacitors, especially from power to ground, or from audio to ground We found that one of them was leaky, and when removed from the circuit, the hum went away. Just a suggestion, good luck in finding the problem. Don, KD9PT - Original Message - From: Mike DeWaele To: Repeater-Builder@yahoogroups.com Sent: Sunday, October 19, 2008 7:28 PM Subject: RE: [Repeater-Builder] Ge mastr 2 link question Paul, Eric Thanks for the response. I did some more testing with your suggestions. I tried hooking both radios up to a deep cycle battery. The hum is still there so I think that rules out the astrons! The audio from the main repeater to the link isn't as bad as from the link back to the main repeater. Both have a hum to them however the 2 meter to the 440 you can hear the voice. the other way all you get is the hum. For testing I have it on the bench in the basement. the only common connection is only the audio and tx lines between the two radios. I have also tried it with a common ground as suggested by NHRC in the controller directions. Both have the same results. I want to make sure it works here before it goes back to the hill. At the site it's just my radio equipment and Wifi internet which has not given me any problems with both machines working there prior to bringing them to my house to work on this linking project. Maybe tomorrow I will give NHRC a call and see if they have run into this problem before. Thanks, Mike KA2NDW -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Paul Plack Sent: Sunday, October 19, 2008 4:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Ge mastr 2 link question Ditto the possible issue with the Astrons, but you may also have too many common grounds. If you have the grounds of the machines interconnected through (1) the power supplies, (2) antenna and/or feedline bonds, (3) rack rails, (4) through the linking cable and (5) an additional, just to be sure ground strap between the radios, you could very easily have a ground loop. Since all the interconnections are made using unbalanced audio lines, you can't just lift the ground at one end as we might try in the pro audio world. Sometimes, a cheapo audio transformer, like the 600-ohm isolation transformers from Radio Shack, are enough to alleviate the loop, because they allow you to leave an audio ground floating from the chassis at one end of the link cable. A quick, cheap investigative tool here is one of the old three-into-two-prong AC plug adapters. If you use it to lift the ground pin on one of the Astrons and the problem goes away, it will be an important clue. Good luck! 73, Paul, AE4KR - Original Message - From: Mike DeWaele To: Repeater-Builder Sent: Sunday, October 19, 2008 1:30 PM Subject: [Repeater-Builder] Ge mastr 2 link question Hi All, I'm having a problem linking two mastr 2 radios together. I have one site and want to full time have my 2 meter and 440 machines linked together. Equipment : (2) Astron R-35 power supplies (one for each machine) (1) Duplexed GE mastr 2 mobile for 2 meter machine. (1) duplexed Ge mastr 2 mobile for 440 machine (1) NHRC-4/M2 controller installed in the 2 meter radio (1) cord made up out of 2 mastr 2 cables Both units were tuned up and working properly as independent repeaters before attempting this project. Then we started the linking project! The radios are linked via the made up cord with the 2 meter machine being the main repeater and the 440 as a slave repeater on the secondary port. The set up works properly on both ports in both directions. The id sounds fine and the courtesy tones are fine. The problem is the repeat audio in both directions has a humming noise that almost sounds like it is being over driven. We have adjusted levels on both the controller and discrimators in both radios to no avail. We do have a common ground between both radios per the instructions with the controller. I'm thinking there is smething that needs to be padded in the audio lines. I'm researching the web but if any one has gone before me with the same project I was hoping to save some time. Thanks, Mike KA2NDW
