I'm slowly working down the noise floor that is bothersome in the lower bands. I've made some decent progress with robust grounding of all my equipment (good for a dB or so) and putting chokes in both ends of my PC-6500 Ethernet cable (a BIG help, it was NOISY). Now I'm told that my many ham shack wall warts (most for USB ports) may be a noise source. While they are small, they are often switching power supplies and potentially noisy. I'd like to replace them.
Does anyone have recommendations for a quiet (linear?) 5V power supply with multiple USB ports?
Does anyone have recommendations for a quiet (linear?) 5V power supply with multiple USB ports?
Posted 2 years ago
Michael Walker, Employee
This document is my bible regarding chokes. I highly recommend every one take a look at it. I've spent hundreds on mix 43 chokes and have been very pleased with the results and how I can hear so much better. http://www.yccc.org/Articles/W1HIS/Co...
Michael - are you sure that is the correct link? Couldn't find any choke article...thx
I think this may have been what he meant for the link.http://www.pi4vli.nl/download/Bijlage_Deltaloep_April_2016_RFI_Ham.pdf
Got it. thx Larry...
Michael Walker, Employee
So sorry. Try this http://www.yccc.org/Articles/W1HIS/Co...
Paul Christensen, W9AC, Elmer
>"Me too. I am discovering noise sources everywhere. Among the worst were two brand new Chamberlin garage door openers."
The latest Chamberlain models are strong RFI/EMI radiators. At my home QTH, I use open feeders located about 20 ft. away from the opener.
The attached photo shows the fix -- as ridiculous as it looks. To get ample turns, wires were extended and include the safety photo-sensor wires. A single #31 toroid is used with several choking turns -- but that wasn't enough. Also seen in the photo are Sprague low-ESR "Orange Drop" bypass caps. That took care of it.
It's insane the extent to which we need to quiet down commercially-made digital devices these days. Hunting down RFI from new home devices and appliances is always a constant battle here.
Wall warts: Thank God Jameco still sells a large selection of linear wall warts. They have both regulated and non-regulated types. I've ordered many over the years as replacements to the junk that's normally supplied with digital devices.
Paul, W9AC
The latest Chamberlain models are strong RFI/EMI radiators. At my home QTH, I use open feeders located about 20 ft. away from the opener.
The attached photo shows the fix -- as ridiculous as it looks. To get ample turns, wires were extended and include the safety photo-sensor wires. A single #31 toroid is used with several choking turns -- but that wasn't enough. Also seen in the photo are Sprague low-ESR "Orange Drop" bypass caps. That took care of it.
It's insane the extent to which we need to quiet down commercially-made digital devices these days. Hunting down RFI from new home devices and appliances is always a constant battle here.
Wall warts: Thank God Jameco still sells a large selection of linear wall warts. They have both regulated and non-regulated types. I've ordered many over the years as replacements to the junk that's normally supplied with digital devices.
Paul, W9AC
I'll be happy with ridiculous if my 160m noise level goes down. I have the torrid, what value were the caps an how did you connect them? From each of the 4 terminals to ground? If so what did you use as ground? I can't tell from the photo how things are connected. Info please.
Paul Christensen, W9AC, Elmer
Right, the Orange Drops are connected from the four terminals to a chassis ground screw at the top of the unit - which of course relies only on the AC third-conductor ground wire. Notice I used 3M Scotchlok IDC splicing connectors to join-up some of the existing opener wiring to the toroid.
The Sprague Orange Drops were on-hand. They are 0.01 uF and physically much larger than necessary because they're rated for 630 VDC. Again, I had a large stock of them but you can get by with a much lower voltage rating. Ugly it is, but it's effective.
Paul, W9AC
The Sprague Orange Drops were on-hand. They are 0.01 uF and physically much larger than necessary because they're rated for 630 VDC. Again, I had a large stock of them but you can get by with a much lower voltage rating. Ugly it is, but it's effective.
Paul, W9AC
Thanks. I had a box full of .01 here that did not help much. I suspect I did not wind enough turns through the toroid. I'l lengthen them and try again. The base of my 160m Inverted L is about 18 feet from the closest opener and my S meter reads 20 to 30 over S9 in the day time. I have been getting by the last month by turning off power to the garage at night. The night time temps were way below zero so it didn't hurt the stuff stored in the upright freezer in the garage. Now that spring is peeking it's head over the horizon I can't do that anymore and need to get it fixed. My calls to Chamberlin were a waste of time. "Gee we never heard any complaints before so our openers must not be making the noise in your radio" Arrrrrgh! Thanks for the info, I'm glad to know it can be fixed.
Just pulled the power from my Sears Craftsman garage door opener. It made no difference to the noise floor on 160 or 80, currently sitting around S4-5. Too bad. Was hoping for a quick fix.
Have also unplugged most of the wall warts near the ham shack and antenna without impact. Where is Sherlock Homes when we need him?
Have also unplugged most of the wall warts near the ham shack and antenna without impact. Where is Sherlock Homes when we need him?
S4 or 5 is really not bad. Remember you will see an S3 with no antenna connected.
Not here. See S0 switched to a dummy load or with antenna disconnected.
Interesting, the 6000 radios are designed to show an S3 with out an antenna.
Ahh. You are correct. S0 is what shows using my ICOM 7300. Switching to the 6500 does indeed get me an S3 without an antenna or into a dummy load. Interesting.
Not grasping the logic behind that.
Not grasping the logic behind that.
In a radio there is always RF around. In SSDR the receiver gets RF from the bins in the bandpass, so even without an antenna the bins are still active and produce a tiny amount of RF. This is a very simple way of saying it.
If you look around there are lots of discussion on this and Steve at Flex explains this in better detail. If your so interested.
If you look around there are lots of discussion on this and Steve at Flex explains this in better detail. If your so interested.
(Edited)
KY6LA - Howard, Elmer
The bins DO NOT GENERATE RF they are a mathematical construct to explain how SDR's receive a signal ;
Background RF is always present - unless you have a perfect Faraday cage around the radio. The 7300 does Not display the true environment but only a relative and basically meaningless approximation of the signal to background The Flex displays what it actually hears
https://d2r1vs3d9006ap.cloudfront.net/s3_images/935425/S-MeterGraph.jpg?1375457399
Can you let us know what the noise level was before and after this fix? This is one thing I have never done (unplug it and see if it make any difference). One thing I have found is the shack laptop dell power supply and very noisy but unplugging it doesn't seem to have any effect on the radios noise level.
According to the graph I'm between rural and quiet rural, about correct for my location. So the QRM is just what it is these days? Too bad. I remember good old days when quiet was quiet.
Reading S3 into a dummy load clearly is not anything like an accurate measurement of what is really coming in the antenna. Seem like my 7300, although less smart, provides a more accurate representation of the antenna noise.
Reading S3 into a dummy load clearly is not anything like an accurate measurement of what is really coming in the antenna. Seem like my 7300, although less smart, provides a more accurate representation of the antenna noise.
Recommendation for a 5v linear power supply?
I too would like to find a 5vdc linear supply. I have gott rid of all my other wall warts and would like to replace the 5vdc ones I still have left.
Looks nice, but not a linear PSU - still a switcher, which is OK if it is proven to be quiet. Of course that's often a crapshoot.
Earlier in this thread Paul W9AC said that Jameco has a large assortment of linear wall wart supplies available.
Have been looking. Hard to tell which ones are linear.
All the USB chargers seem to be current controlled or limited to numbers like 1 amp or 2.1 amps. I'm wondering - is there is a risk to different devices when all the outlets hooked to a 20 amp source? Don't want to fry anything.
You really only need to think about the voltages that some devices need. The amps is just what all devices draw all together.
Larry - W8LLL
These are Mouser part numbers for 31 mix snap on chokes, other
mixes available as well. Pricing improves as your quantity
purchaced goes up.
623-0431167281 Fits LMR-240 10.15 mm ID
623-0431164181 Fits LMR-400 13.05 mm ID
623-0431173551 Fits LMR-600 18.8 mm ID
John - K3MA
http://www.kf7p.com/KF7P/Products.html
John K3MA