Noisy switch gear

I am using an HP Managed Switch in the ‘Shack’ an 1800-24G and it is splattering S8 noise on 145.500. It might have gone ‘bad’, I can swap it with the one in the basement, but that has a fault light flashing so I will have to replace at least one, and sounds like two.


I need a managed switch for trunking (four GB connections between attic and basement). Does anyone use similar gear that you could recommend as RF friendly?

Thanks. Mark. M0NOM

Good gracious, what on earth are you running in your house that needs a 4Gb trunk??? :smile:

Porn. You can’t wait for porn… I’m surprised 4Gbps is enough.

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I’m about to embark on a shack move which brings with it RF cable routing in the wall and CAT6.

I’m planning on using Ubiquiti switches with PoE to power WiFi access points.

Thanks for the heads up on the HP switch and it reminds me to test stuff including the wiring before closing up the drywall.

My new headless Flex 6600 seems to work better when Ethernet connected to my PCs.


Probably not very helpful, but the Asus Router (RT-AC68U) in the shack took a bit of silencing, eventually achieved by attaching an RF earth to the base of one of its antennas, and with copious amounts of ferrite in the power lead. The award for noisiest power supply goes to Open Reach for the power supply for the fibre router – presumably so I didn’t miss the ADSL noise…. Good Luck with finding a quiet switch.
( PS With three teenagers, an X Box which needs eyewateringly large updates for games, TV via i/p, work, which at the moment seems to involve editing a lot of video and online backup the Gb backbone at home is earning its living! ) 73
PS Son passed the last driving test before we moved to Tier 4 - so no more Sundays exploring the great roundabouts of Darlington - however as we are in Tier 4 no Sundays activating either… :frowning:

Hi Mark

I use a small 5 way metal cased Tenda if a 5 way network switch is enough for you. The case is bonded to my shack earth. It is the Tenda TEF1005D model and cost £9.95 new on ebay last May. Came with own wall wart supply which seems to be RF clean. Still available but at a slightly higher price.

All the best

I almost certainly don’t now. At one time I used to have servers running in the basement and servers running in the attic, and I didn’t want to be in a situation where the connection between two ‘sites’ was saturated with a single link. The kind of thing I used to run is old Itanium Servers for example, with 4 GB connections on each box.

Since discovering amateur radio my interest in this kind of thing has waned, and actually when I look at the switch I can probably get away with a 16 port switch now. I do still have a DL360 G5 in the attic, and one in the basement, so I haven’t quite escaped! The SunSDR2 Pro software runs very nicely on a box with 24 cores and 96GB of RAM. It was a ‘giveaway’ from my company during a server refresh.

Regards, Mark. M0NOM

Paul, I would recommend looking at using Cat7 cable and sockets if you are putting new cable in. Although I still don’t tihnk they’ve reached a consensus on what Cat7 is I’m talking about screened cable where it is terminated with a screened socket at both ends.

I have the patch panel in the basement attached to the copper pipework which is earthed. I see this as much a measure in reducing RF noise as protecting against it. In theory I can then move to 10GB ethernet without any changes other than at each end as well.

Regards, Mark. M0NOM.

As whole-of-house heating?

Well, earthed for DC. Once the copper pipe has a finite length away from the earth connection point it is not earth for RF. At every frequency on which it is an odd number of quarter waves long, it is an open circuit. The nice copper pipe may help on specific frequencies but is by no means a dead short for HF and VHF/UHF RF. It’s part of your antenna system.

Clip-on chokes only produce a small amount of inductance. I suggest using a core similar to a balun core, with 5 to 10 turns through it. Chokes need inductance.

73 Andrew VK1DA/VK2UH

Thanks for the info Andrew, and I did suspect as much. It would be easy enough to detach the connection, and possibly move it to the earth entering the house, which would probably reduce the RF in the house just because the cable exits the house close by.

If replacing the switch doesn’t improve the situation I will certainly look at a large ferrite on the mains cable, there are lots of things to try.


Possibly useful viewing RSGB Convention lecture 2015 - Clean up your shack - YouTube ( RSGB Lecture - Clean up your shack ) Paul

Ok, so just to further complicate it, you would need to assess the total length of the conductor from your radio to the point you regard as “earth”. It is that total length that needs to be considered when calculating quarter wave multiples.
It’s not an easy problem to diagnose or solve.
Good luck.
Andrew VK1DA/VK2UH

Thanks Mark for the suggestion. I did look at CAT7 but as its still not an official standard (I think), I opted for CAT6A F/UTP which is 4 sets of twisted pair and a shield around all 4. I think that represents the current evolution of the CAT6 family. I did see some of the shielded RJ45 connectors for sale and should go back and research them further.


Found the source of the problem - a Power over Ethernet injector for my MITEL work phone. Adding a choke on the mains power supply and on both of the ethernet cables dropped it from S8 to S1-S2, and better still now I’ve finished work for the day I can unplug it completely!

I do need to have a complete reorganisation of all this RF, mains and networking cabling so will watch the video thanks @G4IPB Paul and put a plan together to minimise the interference caused. I have an HF antenna to go up at some point, so this is all worthwhile now.

In the meantime I’ll take a look at PoE switches and see if something fits the bill as a replacement.