What say you?
Here at VE9KK's household, my XYL has returned to part-time work from home and involves a computer and the internet to communicate regarding work. Last week while she was working and I was on the radio she told me her LAN connection kept dropping out. I did some experimenting and sure enough, it was my CW signal on 15m that was doing it. I quickly grabbed my last FT240-43 toroid and wrapped the CAT6 cable around it which did the trick!
I then did some reading and learned that the CAT cable should be loose around the toroid and not tight as this affects the small wire inside the CAT6. I also read that 7 turns were the magic number of turns. Finally and this is the question to my readers I read two thoughts on wrapping CAT cable around a toroid. One school of thought was it is perfectly fine and the other was it slowed down the internet speed? I never did a speed check on my wife's connection with and without the toroid. The reason for this is she never complained the speed dropped so why poke the bear! Has anyone out there had an issue with your HF signal dropping internet connections at home and what did you do about it?
Maybe a shielded CAT 6 cable would eliminate the interference w/o a toroid!
Sounds familiar. I switched all CAT6 to highly shielded CAT7 and sprinkled clamp-on ferrites everywhere. In my office, my station is located next to the cable modem and Apple Extreme router and HF would cause the router to re-initialize. Apple suggested making sure the router was on a different mains power circuit and that solved it. Remember all those CAT cables are little antennas, so filtering and shielding becomes essential. Good luck!
Good evening Arne, thanks for stopping by and leaving a comment. That was the first thing I did was to use a shielded CAT5 but ended up with the same results. The shielded CAT5 was just too clumsy for the toroid. I then used a small diameter easy-to-fit CAT5 cable. So to answer your question I did use a shielded CAT5 W/O a toroid but it did not work!!!
73 and have a good upcoming week.
Good evening David very nice to hear from you and thanks for taking the time to leave a comment. I did try a shielded cable but I did notice our router CAT connector is all plastic and the same at the other end on my wife’s unit. Makes me think the shield in the CAT cable has nowhere to drain. The toroid seemed to do the job but I may change the turns to 7 and not as tight.
I am with Arne, K5ARN. Shielding works, however it can be a challenge to get a good bond at the ends of the LAN cables. My system has a LAN cable that has a copper corrugated shield just like coaxial hardline. Here again getting a low impedance path from the shield to the hardware can be a tough nut to crack. As far as speed reduction, I doubt that it would be significant. The E/M field is contained between the balanced pairs.
Old timers will remember when 300 Ohm shielded TV twin lead was used in steel conduit runs. All things considered, the use of ferrite in a toroid or a stack of beads at each end is the route that seems most promising. As a side note, my HF station always killed our old DSL service.
Good evening Larry thanks for taking the time to leave a comment, I agree regarding getting a good bond at the ends where the LAN terminates to the router and the terminal. Both components of CAT female connectors are plastic. I may end up keeping with the toroid.
Ethernet cable, Cat 5 or better, is 4 sets of twisted pairs, with the twist rate varying over the length of each pair, and different from the other pairs at the same point, to reduce the loose coupling between pairs, and between any of the pairs and an external source, like a noisy power circuit. As we see in ladder line antenna feeds, the twist just reduces the common-mode coupling from the exterior, without interfering with the differential mode currents within each pair that actually carry the data. Ferrite chokes, properly applied, and of the right materials, add to the effect of the twist — reduced, undesired common-mode coupling, without reducing the common mode current. I would think Mix31 would be a good choice, but I am no engineer. Here is a good discussion of materials: https://palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-mix-selection [I don’t get any fabulous discounts for this link, even though I should. :)]
73, KA5NEE, EM66ii
4th sentence from the end, “reducing the common mode current” should read “reducing the differential mode current.” I plead advanced age, and too close to bed time. 73, KA5NEE
Please note that when RF and Data intermix, the problem usually goes both ways! An increased noise floor on the bands usually occurs as well as corrupted data when isolation breaks down.
The first Mobile Data Terminals installed in our patrol cars did have issues both ways. The Communications group was not consulted on the project, since the MDTs used cell modems, which was considered neither radio nor telephone in the staff’s eyes, it was just IT.
The first mobile units had CPUs in glove boxes, with “antenna wires” running to separate monitors, keyboards, and printers. Transmissions would blank the PCs, plus cars in fringe areas couldn’t hear dispatch. Effective sensitivity testing on sample vehicles showed a 20 dB increase in the noise floor with the MDTs turned on. Communications could try to license 10,000 watt replacement base station transmitters (not), or get the ‘vehicle committee’ to work on mobile solutions.
For reference, the fixes arrived at were:
– IT replaced all the MDTs with all-in-one CPU/monitor units, eliminating some cables
– Radio Unit changed the VHF antenna whips to end-fed half wave, not ground plane referenced quarter or 5/8 wave in order to cut down on RF currents on the vehicle
– Radio Unit ensured the roof mounts kept the transmission line shielding passing through the roof in the mount instead of using the cheap Motorola/GE/PCTel roof mounts with the exposed center conductor soldered to a pin on the mount’s underside inside the vehicle cabin. (The shielded mounts were previously demonstrated to give better transmit range from fringe patrol areas.)
I have bought some shielded ethernet cable for when I am ready to migrate from WiFi. I will also pull it in ‘MC’ type flex conduit. Note that AM station engineers ground cable shields at one end only to prevent ground loops. I will probably leave extra drain out of the connectors at one end, and solder ground jumpers to those.
Just thinking about the original post, maybe pulling the cables tight to the toroid instead of making loose loops is what might slow some data speeds? Making 90 degree bends of the individual data pairs inside the jacket might be seen electrically as a bunch of series inductors, no???
Good morning Tom, thanks very much for the great link and I have been to Palomar’s website in the past, there is some great information there. With how you explained the cable construction of CAT cable it would seem safe to say that adding a toroid would help remove the issue I am having as it did just that. Thanks for the info and the link.
Good morning N1YR (Tom), now that was a process for sure! All my internet connections for the shack are WIFI and I have no issues at all. My XYL work setup does not use WIFI and thus the CAT cable connection and new issue. The company’s IT person is coming over today to install a separate modem for her and a new CAT cable, not sure if shielded or not. I will speak with him about the issue but if all else fails again I will go back to the toroid and apply it loosely around the toroid this time.
Tom thanks for the comment and taking the time to read the post,