Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
Hi Jim, Thanks, and I have shared a lot of documents with the folks that cover the major points your section on variable speed drives covers, but found that I still had to make a recommendations list for them (taking into account simplicity of install, cost, and highest probability of success), while at the same time telling them that I was not liable for anything they opted to do. Actually sounds like the technician is now trying to get approval to move the drives up into the attic which would put them very close to the motors (which are roof mount) and at the same time he would do a much better job on the conduit run between the drives and the motors. Currently the drives are around 50 feet away from the motors with very questionable conduit runs (and the current conduit runs are impossible to access). Note : Previously one simple option I suggested was the use of common mode cores on the output of the drives (similar to what George AA7JV suggested), but the original technician that was working on the job did not contact me for assistance and he installed the cores incorrectly which caused drive faults, so they abandoned that approach (I'm giving them some time and space before I bring up the common mode cores again). I also want to develop a better working relationship with the current technician (I have offered to be onsite with him when he makes changes, but he has yet to take me up on my offer). I would like to make one comment about your section on VFDs. It does not mention shielded cable that is now available specifically for use on the output side of variable speed drives, and these cables offer some major advantages over the use of metal conduit (but at much greater expense). 73, Don (wd8dsb) On Wed, May 13, 2015 at 2:41 PM, Jim Brown j...@audiosystemsgroup.com wrote: On Wed,5/13/2015 11:14 AM, Don Kirk wrote: The local technician is now planning on additional changes since the input line filters have not totally mitigated the problem (but they sure helped), and will provide an update when I have new information to share. Hi Don, You might want to refer the people working on the problem to this Power Point for a tutorial workshop that I've taught to pro audio and video people. The principles are no different when the interference is at RF. http://k9yc.com/InfoComm-Grounding2012.pdf Henry Ott's excellent text on EMC includes a sub-chapter on these very nasty RFI sources. His book is widely used as an EE text, and considered the EMC bible. http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
Don, you should request that the technician install the new conduit runs using compression couplings and connectors instead of the more common setscrew type. Compression couplings make a much better electrical connection between sticks of conduit which will be better to keep the conduit acting as a proper shield. The manufacturer of the motor drive will likely specify a maximum wire distance between the drive and the motor. It sounds like you're lucky and have a tech that wants to help! Bill KB8WYP Presently in Dayton and hoping it doesn't rain all weekend. Sent from my iPhone On May 14, 2015, at 10:32 AM, Don Kirk wd8...@gmail.com wrote: Hi Jim, Thanks, and I have shared a lot of documents with the folks that cover the major points your section on variable speed drives covers, but found that I still had to make a recommendations list for them (taking into account simplicity of install, cost, and highest probability of success), while at the same time telling them that I was not liable for anything they opted to do. Actually sounds like the technician is now trying to get approval to move the drives up into the attic which would put them very close to the motors (which are roof mount) and at the same time he would do a much better job on the conduit run between the drives and the motors. Currently the drives are around 50 feet away from the motors with very questionable conduit runs (and the current conduit runs are impossible to access). Note : Previously one simple option I suggested was the use of common mode cores on the output of the drives (similar to what George AA7JV suggested), but the original technician that was working on the job did not contact me for assistance and he installed the cores incorrectly which caused drive faults, so they abandoned that approach (I'm giving them some time and space before I bring up the common mode cores again). I also want to develop a better working relationship with the current technician (I have offered to be onsite with him when he makes changes, but he has yet to take me up on my offer). I would like to make one comment about your section on VFDs. It does not mention shielded cable that is now available specifically for use on the output side of variable speed drives, and these cables offer some major advantages over the use of metal conduit (but at much greater expense). 73, Don (wd8dsb) On Wed, May 13, 2015 at 2:41 PM, Jim Brown j...@audiosystemsgroup.com wrote: On Wed,5/13/2015 11:14 AM, Don Kirk wrote: The local technician is now planning on additional changes since the input line filters have not totally mitigated the problem (but they sure helped), and will provide an update when I have new information to share. Hi Don, You might want to refer the people working on the problem to this Power Point for a tutorial workshop that I've taught to pro audio and video people. The principles are no different when the interference is at RF. http://k9yc.com/InfoComm-Grounding2012.pdf Henry Ott's excellent text on EMC includes a sub-chapter on these very nasty RFI sources. His book is widely used as an EE text, and considered the EMC bible. http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
On Wed,5/13/2015 11:14 AM, Don Kirk wrote: The local technician is now planning on additional changes since the input line filters have not totally mitigated the problem (but they sure helped), and will provide an update when I have new information to share. Hi Don, You might want to refer the people working on the problem to this Power Point for a tutorial workshop that I've taught to pro audio and video people. The principles are no different when the interference is at RF. http://k9yc.com/InfoComm-Grounding2012.pdf Henry Ott's excellent text on EMC includes a sub-chapter on these very nasty RFI sources. His book is widely used as an EE text, and considered the EMC bible. http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
Don, I have referred to VFD-s in an early posting as RF Weapons of Mass-Destruction. Still, they are useful and I got one in my house. As the contractor in your description did, I installed a line filter on the input side. I also installed a three wire common mode choke on the three phase output (6 turns on a large #31 core) very close to the output terminals. I also added three 3.3 nF high voltage mica caps on the load side between each phase wire and ground. I used a wide braid strap for grounding. My RX antenna is about 200 feet from the drive but its noise is now well below my noise floor and I can not tell when the drive is running. Good luck getting rid of the rest of noise. Unfortunately, for all of us, we will increasingly see more of these drives residential buildings. GW On Wed, 13 May 2015 11:41:28 -0700 Jim Brown j...@audiosystemsgroup.com wrote: On Wed,5/13/2015 11:14 AM, Don Kirk wrote: The local technician is now planning on additional changes since the input line filters have not totally mitigated the problem (but they sure helped), and will provide an update when I have new information to share. Hi Don, You might want to refer the people working on the problem to this Power Point for a tutorial workshop that I've taught to pro audio and video people. The principles are no different when the interference is at RF. http://k9yc.com/InfoComm-Grounding2012.pdf Henry Ott's excellent text on EMC includes a sub-chapter on these very nasty RFI sources. His book is widely used as an EE text, and considered the EMC bible. http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
I've not reported on this issue in a long time, but finally making progress with interference that's originating from an apartment complex 0.4 miles away. Back on Dec 11, 2014 we (myself and the apartment complex maintenance manager) tracked the problem down to the variable speed drives that are part of their kitchen air makeup system. In this system there are two drives that operate together, with one being a 3 HP drive for the kitchen hood exhaust fan, and the other is a 5 HP drive for air makeup. Here is a link to a video I uploaded onto youtube that captures the interference when the drives start up (really an interesting video using an RTL-SDR receiver and upconveter). http://youtu.be/LIWd2Dd-Fa0 On Jan 30th of this year I made a list of recommendations, with the understanding that the apartment complex and their suppliers were fully responsible for any changes made to their system (I assumed no liability for their actions to mitigate the interference). After a long period of time and no action, I called the FCC (March 3rd) and was told I should file an official online complaint with the FCC which would then initiate action by the FCC enforcement division. I passed this info onto the apartment complex regional maintenance manager, and that is when things started to move forward. The out of state firm that designed the kitchen air makeup system hired a local mechanical/electrical firm to work on the problem, and the local technician has been very proactive. 3 weeks ago input line filters manufactured by the variable speed drive manufacturer were installed on both drives, and this definitely reduced the level of interference. Start up peaks spaced 4 khz apart were originally 15 dB above my noise floor and after installation of the input line filters they are now 5 dB above my noise floor. The very broad band white noise that develops a short time after start up is now very hard to detect whereas it was previously 4 to 6 dB above my noise floor. The local technician is now planning on additional changes since the input line filters have not totally mitigated the problem (but they sure helped), and will provide an update when I have new information to share. For more in depth details see my website that's documenting this case http://sites.google.com/site/broadbandrfi/ 73, Don (wd8dsb) On Fri, Oct 24, 2014 at 2:40 PM, Don Kirk wd8...@gmail.com wrote: Recently noticed an increase in my noise level on 160 meters (in the direction of my 300 degree pointed pennant), and about 3 weeks ago I tracked it down to a new apartment complex which is located 0.41 miles away. Today I noticed that the signal had a repeating pattern of approximately 30 minutes on and 5 minutes off when listening at my house, so I jumped in the car and drove over to the apartment complex to make sure the signal at the apartment complex had the same repeating pattern and was in time sync with the noise at my house. Thankfully it was, and I made recordings at the apartment complex today showing I could predict when the signal would go off and come back on based on the time pattern I was following at my house. I have created a website documenting my direction finding activities for this broadband RFI case, and uploaded my prediction recording today. Here is the link to my simple website that documents this case : http://sites.google.com/site/broadbandrfi/ I contacted the apartment complex today notifying them that I was now 100% confident that the broadband noise was originating from their building, and will now work with their management to locate the exact source so they can follow up with the manufacturer of the equipment for resolution. Based on what I have heard so far it sounds like a motor (probably a variable speed motor controller), but that's just a guess at this time (sounds like it's winding up in speed when it first comes on and you can hear this on the recording I made at the apartment complex today). Just FYI, and another very interesting one to track down. 73, Don Kirk (wd8dsb) _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Boradband noise on 160 meters tracked down to apartment complex
Mfj Nuller will not work because the signal is in the same direction of my 300 deg pointing pennant. My guess is that we should be able filter and shield properly at the source Don On Sunday, December 14, 2014, W2PM via Topband topband@contesting.com javascript:_e(%7B%7D,'cvml','topband@contesting.com'); wrote: Sounds like a job for the MFJ nuller. The good news being its a point source and should be easily handled. It may cost you several months of frustration for no good outcome otherwise but perhaps it's worth a try if there is a simple bonding issue there. Sent from my iPad On Dec 14, 2014, at 01:08, Jim Brown j...@audiosystemsgroup.com wrote: On Sat,12/13/2014 5:35 PM, Don Kirk wrote: Now going back to the contractor that installed the equipment in an attempt to better understand the hardware in the unit That smells like a Variable Speed Drive, the heart of which is a switching power supply that generates pulses in the 10 kHz range, the width of which are varied to control the speed of the motor. Lots to go wrong here -- switching power supply, square pulses of big current running a distance between the controller and the motor, often with supply and return conductors widely separated from each other, and with controller and motor widely separated, so the current flows in a large loop. Can you say train wreck? 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
I have done a little bit of research into the variable speed drive motors that are commonly part of eco-friendly green HVAC systems. I have found in many cases that the installer sells SEER-rated components as part of their most efficient packages, but in most cases the installation takes no advantage of the variable speed drive capabilities of the SEER-rated blower and compressor motors because they are wired up to work only at a single speed. In my particular case, my house's HVAC had a blower motor that failed. It was a $1100 SEER-rated variable speed blower motor. It was only 3 years old. It was only wired up to work at a single speed. I replaced it with a $200 capacitor-start motor. Tim N3QE On Sun, Dec 14, 2014 at 1:08 AM, Jim Brown j...@audiosystemsgroup.com wrote: On Sat,12/13/2014 5:35 PM, Don Kirk wrote: Now going back to the contractor that installed the equipment in an attempt to better understand the hardware in the unit That smells like a Variable Speed Drive, the heart of which is a switching power supply that generates pulses in the 10 kHz range, the width of which are varied to control the speed of the motor. Lots to go wrong here -- switching power supply, square pulses of big current running a distance between the controller and the motor, often with supply and return conductors widely separated from each other, and with controller and motor widely separated, so the current flows in a large loop. Can you say train wreck? 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
Sounds like a job for the MFJ nuller. The good news being its a point source and should be easily handled. It may cost you several months of frustration for no good outcome otherwise but perhaps it's worth a try if there is a simple bonding issue there. Sent from my iPad On Dec 14, 2014, at 01:08, Jim Brown j...@audiosystemsgroup.com wrote: On Sat,12/13/2014 5:35 PM, Don Kirk wrote: Now going back to the contractor that installed the equipment in an attempt to better understand the hardware in the unit That smells like a Variable Speed Drive, the heart of which is a switching power supply that generates pulses in the 10 kHz range, the width of which are varied to control the speed of the motor. Lots to go wrong here -- switching power supply, square pulses of big current running a distance between the controller and the motor, often with supply and return conductors widely separated from each other, and with controller and motor widely separated, so the current flows in a large loop. Can you say train wreck? 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
On Sat,12/13/2014 5:35 PM, Don Kirk wrote: Now going back to the contractor that installed the equipment in an attempt to better understand the hardware in the unit That smells like a Variable Speed Drive, the heart of which is a switching power supply that generates pulses in the 10 kHz range, the width of which are varied to control the speed of the motor. Lots to go wrong here -- switching power supply, square pulses of big current running a distance between the controller and the motor, often with supply and return conductors widely separated from each other, and with controller and motor widely separated, so the current flows in a large loop. Can you say train wreck? 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Boradband noise on 160 meters tracked down to apartment complex
Recently noticed an increase in my noise level on 160 meters (in the direction of my 300 degree pointed pennant), and about 3 weeks ago I tracked it down to a new apartment complex which is located 0.41 miles away. Today I noticed that the signal had a repeating pattern of approximately 30 minutes on and 5 minutes off when listening at my house, so I jumped in the car and drove over to the apartment complex to make sure the signal at the apartment complex had the same repeating pattern and was in time sync with the noise at my house. Thankfully it was, and I made recordings at the apartment complex today showing I could predict when the signal would go off and come back on based on the time pattern I was following at my house. I have created a website documenting my direction finding activities for this broadband RFI case, and uploaded my prediction recording today. Here is the link to my simple website that documents this case : http://sites.google.com/site/broadbandrfi/ I contacted the apartment complex today notifying them that I was now 100% confident that the broadband noise was originating from their building, and will now work with their management to locate the exact source so they can follow up with the manufacturer of the equipment for resolution. Based on what I have heard so far it sounds like a motor (probably a variable speed motor controller), but that's just a guess at this time (sounds like it's winding up in speed when it first comes on and you can hear this on the recording I made at the apartment complex today). Just FYI, and another very interesting one to track down. 73, Don Kirk (wd8dsb) _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Boradband noise on 160 meters tracked down to apartment complex
Just a helpful tidbit for anyone working with motor controllers / drives / VFDs / frequency drives / etc. (lots of names for the things :-): The manufacturers usually specify that the wiring between the VFD and the motor be in conduit. This is to help with EMI/RFI issues. There is usually also a relatively short maximum reach specified (20-50 feet or so). Obviously they mean *metal* conduit for shielding, but I've seen electricians use plastic conduit -- especially for flexible applications -- before. The flexible conduit is commonly known as Sealtite in the trades even though that is just one manufacturer of the stuff. It's normally a flexible metal conduit with a plastic outer jacket. There is also an all-plastic version of the stuff. You can tell them apart by the look and feel once you've seen both, but another way is that the jacket markings on the metal inside plastic kind will say something about needing to use a separate grounding wire if the circuit is more than some number of amps. The all-plastic kind will not have that marking. The reason for the marking is that the steel part of the conduit is thin and usually can't be a suitable ground connection for safety purposes for more than 20-30 amps or so. There is also the usual flexible metal conduit (usually known as greenfield, or MC cable (for Metal Clad cable) if it has factory installed wires) which has a spiral metal outer jacket that is conductive. If your noise source ends up being some kind of motor drive, I'd check to make sure the wiring between the drive and the motor are in some kind of metal conduit. It's an easy thing to look for and might also be the cause of the problem. -Bill -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don Kirk Sent: Friday, October 24, 2014 2:41 PM To: topband Subject: Topband: Boradband noise on 160 meters tracked down to apartment complex Recently noticed an increase in my noise level on 160 meters (in the direction of my 300 degree pointed pennant), and about 3 weeks ago I tracked it down to a new apartment complex which is located 0.41 miles away. Today I noticed that the signal had a repeating pattern of approximately 30 minutes on and 5 minutes off when listening at my house, so I jumped in the car and drove over to the apartment complex to make sure the signal at the apartment complex had the same repeating pattern and was in time sync with the noise at my house. Thankfully it was, and I made recordings at the apartment complex today showing I could predict when the signal would go off and come back on based on the time pattern I was following at my house. I have created a website documenting my direction finding activities for this broadband RFI case, and uploaded my prediction recording today. Here is the link to my simple website that documents this case : http://sites.google.com/site/broadbandrfi/ I contacted the apartment complex today notifying them that I was now 100% confident that the broadband noise was originating from their building, and will now work with their management to locate the exact source so they can follow up with the manufacturer of the equipment for resolution. Based on what I have heard so far it sounds like a motor (probably a variable speed motor controller), but that's just a guess at this time (sounds like it's winding up in speed when it first comes on and you can hear this on the recording I made at the apartment complex today). Just FYI, and another very interesting one to track down. 73, Don Kirk (wd8dsb) _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
