Hi,last cry for help before giving up,tried different ants same problem key up and the modem disconnects much to the disgust of of the station master tried inverted L/V now if I go on 10mt with a Imax 2000 full power no problem,was looking at the Cobwebb because of the low EMC But not sure if that will work!!! any thoughts would be appreciated as to where the problem lies.Don

depending where your antennas are in relation to the modem,its possably getting in via the mains so a clamp on ferrite on mains ,ether lead etc .
should help,failing that try the connections to the pc ,my keyboard & mouse used to freeze a ferrite cured it.
is your radio equip earthed? do you have any rf chokes on antennas?
i got a problem when beaming short path vk,zl i freeze our tv if its running through the diggi recorder ,unplug recorder no probs.ferrites every where just to much pre amping to tv with diggi box but the good lady will insist on using two things to watch the same programme??

Well thanks for your reply,modem has a ferrite where goes into modem but I think it will be only about 9v as the mains adaptor plugs directly into mains so no chance of fitting one there,(my shack is outside by the way) no balun (RF) just the balun at feed point using
a inv v not very high about 20' I (need to keep a low profile here) does run near telephone lines about 6-8' away this where I thought problem was!!!.
do have a ferrite on telephone line feed into house,radio,tuner connected to copper pipe on bench to earth out through shack to 3' copper rod into ground, telly etc not affected . Don

I had a similar problem on Topband. Whenever I tx'd on this band, the modem would slow right down and sometimes drop out. A couple of ferrite rings (one on the phone line, one on the DC supply lead) sorted it. Plenty of turns were required 'cos of the low frequency involved.

personally i would make sure you have a decent RF earth sorted before trying to mask a problem. An inverted L or any end fed without adequate ground is going to cause issues..


billy

I have the problem on 80m when using more than 75W on data modes. When I measured the phone line from the house to the pole, guess what.....damned near perfect 1/4 wave on 80m. I have no RF common mode issues so its a coupling issue and there's not a lot I can do as ferrites aren't doing a thing.

you say shack outside how is electric fed to shack?
could it be rf on that cable? if overhead or run down fence (like a lot of them)
jut a thought

What type of choke are you using? With really high levels of RF on domestic leads a single snap-on bead probably wont be adequate; you need a choke comprising multiple turns on Type 31 or Type 43 material, and you may need more than one of them on any one lead.

Steve G3TXQ

Hi, thanks for comments so far,mains to shack is via an extension lead from an outdoor socket through a RCD trip cable is on the ground not overhead, have laid some ground wires with improvment now tunes on 80 where it would'nt before.
I will try some more chokes have a choke balun that has about 7or 8 frrite on it so will try winding a few of those and the results,I can tx be it low power with no effect on modem but when upping power does knock it off but comes back with out me resetting box I will try 1or 2 chokes and see but we seem to be making headway. Don

Hi, Did not resolve it, so have taken the dipole down and just leaving 10mts up, thanks for replies and the seasons greetings to one and all.Don