Help with Broadband Router QRM?

Author Post

Alec, G3YOA

Tue Apr 14 2009, 11:36AM
On receive I have various carrier groups between 50.06 and 50.333 spaced about 30 Khz apart  and between 50.36 to 50.88 at 40 Khz apart at a signal strength 57-58 my Tx Rx is an FT847. On investigation it was found to come from my router-PC link which is not wireless , on unplugging this link the noise stops. Can anyone help me in filtering this problem. Alec G3YOA
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Trev, EA5ISZ
Tue Apr 14 2009, 02:58PM
Trev, EA5ISZ

Registered Member #13
Joined: Tue Mar 18 2008, 01:43PM

Posts: 143
It may not help but can you determine whether the problem is from the router or from the PC as various 'handshake' sequences occur between the two.
Is the problem still there with the router connected but switched off?
Is the problem there with the router on but disconnected at the PC end only?
You could try the ethernet cable or USB cable depending upon which you are using wrapped around a standard ferrite ring. Place the ring at one end of the cable and then reverse the cable (in the case of ethernet) to try it at the other end. In the case of USB try two rings, one at each end.

Can't think of much else at present Alec but maybe that'll help else someone else may have an alternate solution.

Cheers, Trev
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Johan, ON4IQ
Tue Apr 14 2009, 05:07PM
Johan, ON4IQ
Registered Member #52
Joined: Wed Mar 19 2008, 12:21PM

Posts: 14
try forcing the ethernet ports to 10mbps. My rputer at 100Mbps is generating birdies but when forced into 10Mbps setting birdies go away.
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Alec, G3YOA
Wed Apr 15 2009, 09:41PM
Alec, G3YOA
Registered Member #886
Joined: Mon Apr 13 2009, 10:28PM

Posts: 3
Thanks Trev . The problem is thereonly when the ethernet lead is connected , if I disconnect it from either end the carriers stop . I have used adhesive foil to screen then covered the lead and connected one end to the PC chasis this helped a little . Next I put a ferrite filter in the router end and this bought it down from S7 to S2 and then tried another at the PC end and it reduced to S1 . The only sucessful way is to unplug the router end when I go on 6m ., The router is a ' Speedtouch ST585 v6 '
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Alec, G3YOA
Wed Apr 15 2009, 09:46PM
Alec, G3YOA
Registered Member #886
Joined: Mon Apr 13 2009, 10:28PM

Posts: 3
Hi Johan, Thanks for your reply I am wondering how the speed change is achieved. My router is a ' Speedtouch ST585 v6 '
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Uffe, PA5DD
Fri Apr 17 2009, 08:01AM
Uffe, PA5DD
Registered Member #218
Joined: Wed Apr 09 2008, 08:48AM

Posts: 9
Most likely you cannot set this in the SpeedTouch router, but you can in the PC. Control Panel > Network > Right-click "LAN connection" > Configuer > Advanced > Speed > 10 Mb Full.

It might look a bit different, but you should find your way.

Also check if your Ethernet cable is STP (Shielded Twisted Pair) and not UTP (Unshielded Twisted Pair).

It's not a bad thing if your problem is caused by the Ethernet signal. It's easier to cure than the cases I have seen, where the interference was caused by the router switch mode power supply. The common cure here has been to dump the router, and buy one of another make.

GL 73 Uffe PA5DD

[ Edited Fri Apr 17 2009, 08:01AM ]
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