Re: Topband: ROKU 3 QRM
Nearly all lower frequency noise ingress and egress is from differential mode of different cables entering and leaving a device. Any individual cable or wiring by itself might be common mode or differential mode, but the nasty stuff that isn't filtered almost always is from two or more cables or wire groups that are excited in "push-pull" at the device. This makes external wiring look like a big loop or big antenna system, so even small noises can go a long distance. The very first thing I do is get one of those multiple port lightning arrestors or surge protectors and make sure every cable and wire leaving a system passes through that common point and everything that can be grounded or bonded or bypassed is bypassed with that "protector" as a common point. 73 Tom - Original Message - From: "Dennis W0JX via Topband" To: Sent: Thursday, September 18, 2014 3:41 PM Subject: Topband: ROKU 3 QRM Topbanders: Within the last 3 to 4 months, I have been plagued with very strong QRN. I have a two way beverage that party runs over my garage and next to the house but it had always been an excellent performer in the past. However, in the reverse direction the QRN was intense, well over S-9 while about S-5 in the forward direction. Today, I decided to track the source down. I though it might be the new neighbors who moved in to the south since the beverage points southwest at their home. However, I decided to start inside my own home first. I set the QRN for S-9 on my K3 and began unplugging devices. It only took three attempts! When I pulled the power on the relatively new ROKU 3, the noise level on the K3 dropped from S9 to S5, about 24 db! I then plugged in the ROKU power supply thinking it might be a switcher but the noise did not rise so it is coming from the ROKU 3 itself. Our previous much older original ROKU did not do this. Now I'm going to have to deal with the XYL who is addicted to watching TV series on the darn thing! Any ideas on how I can shield, isolate, or modify this thing without causing a major operational issue? By the way, the noise output of the ROKU declines with an increase in frequency. On 80 meters, there was a slight increase in noise but not signficantly so and no effect on 40. Lesson learned: ALWAYS start your search inside your home first. 73, Dennis W0JX Milan, Ohio _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4765 / Virus Database: 4015/8233 - Release Date: 09/18/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ROKU 3 QRM
" from a 12V battery that is floated by a small linear supply. (A year or so ago, I went through my home and got rid of all the switch-mode crap). At last count, I have more than a dozen linear supply replacements here. Some are built into consumer A/V equipment, others are used to power routers, Ethernet switches, cell phones, etc. I like the PowerOne, Condor, and International Power branded open frame "OEM" supplies. I grab extras any time they come available on the surplus market - and often for well under new prices from Mouser and Newark. Tackling EMI is always a maddening exercise here. If there's the slightest noise bump on a panadapter display, I can't rest until it's gone. Just this morning, I replaced what I thought was a quiet Toshiba laptop supply. It was being used to power a low-power SDR transceiver. All was fine until I ventured down to the middle of the AMBC band this morning. The grunge level increased over 30 dB when compared to 160m. Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ROKU 3 QRM
On Thu,9/18/2014 12:41 PM, Dennis W0JX via Topband wrote: When I pulled the power on the relatively new ROKU 3, the noise level on the K3 dropped from S9 to S5, about 24 db! RF noise is radiated by wires, in this case, the power supply wiring and the wiring between the Roku and your TV (and perhaps other wires connected to the TV). I have a Roku 3, and while I hear it in a TH-F6A with its loopstick an inch above the Roku box, I don't hear it in my antennas. I'm doing two things to make it quiet. First, I'm running it from a 12V battery that is floated by a small linear supply. (A year or so ago, I went through my home and got rid of all the switch-mode crap). Second, both the DC lead and the video cable have a multi-turn ferrite choke wound on Fair-Rite #31. It also helps that my antennas are at least 100 ft from the Roku 3. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ROKU 3 QRM
Get rid of the ROKU and get a modern TV with the web based apps built inthen connect the tv to the internet and/or satellite. I have a VISIO 65" 3d tvnon plasma of course...works greatno QRM to or from the tv. 73 David Harmon K6XYZ Sperry, OK -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Dennis W0JX via Topband Sent: Thursday, September 18, 2014 2:42 PM To: topband@contesting.com Subject: Topband: ROKU 3 QRM Topbanders: Within the last 3 to 4 months, I have been plagued with very strong QRN. I have a two way beverage that party runs over my garage and next to the house but it had always been an excellent performer in the past. However, in the reverse direction the QRN was intense, well over S-9 while about S-5 in the forward direction. Today, I decided to track the source down. I though it might be the new neighbors who moved in to the south since the beverage points southwest at their home. However, I decided to start inside my own home first. I set the QRN for S-9 on my K3 and began unplugging devices. It only took three attempts! When I pulled the power on the relatively new ROKU 3, the noise level on the K3 dropped from S9 to S5, about 24 db! I then plugged in the ROKU power supply thinking it might be a switcher but the noise did not rise so it is coming from the ROKU 3 itself. Our previous much older original ROKU did not do this. Now I'm going to have to deal with the XYL who is addicted to watching TV series on the darn thing! Any ideas on how I can shield, isolate, or modify this thing without causing a major operational issue? By the way, the noise output of the ROKU declines with an increase in frequency. On 80 meters, there was a slight increase in noise but not signficantly so and no effect on 40. Lesson learned: ALWAYS start your search inside your home first. 73, Dennis W0JX Milan, Ohio _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
