Ferrite cores

DrTeeth

@ WA2SQQ
Sorry for my earlier misunderstanding. I borrowed a wireless adaptor and the network connection died even when the Ethernet cable was disconnected. I don't know if that gives anybody any clues as to what is going on.

Somebody sent me links to UK suppliers of the type of large ferrite rings and quality baluns that you state side chaps have sent. So good to go once recovered.

KY6LA_Howard

@Guy When you earthed the computer case, did you scrape the paint off all the **** connections in the case so that it was a complete Ferraday Shield? I found that even a Small amount of paint will stock conductivity and leave the case floating. Also put ferrites on the computer power leads and all the monitor leads. One trick I use to find where the RFI ingress is to use a very large ferrite that I clamp on every lead. Once I discover the offending source, I use just enough smaller ferrites to fix the issue. BTW. Fixing RFI seems to be a never ending issue as you only have to move a single lead somewhere and it magically reappears.

DrTeeth

Hi Howard,

I fixed the lead to bare/unpainted metal, but the side panels are painted. They slide into bare metal but I will have to check the panels themselves. Thanks for the heads-up.


WA2SQQ

Guy I think you are getting closer to finding a solution. Seeing that the wireless connection didn't solve the problem, we can probably conclude that your CAT5 INTERNET connection is not the main source of unwanted RF. When you loose the connection, I assume you also loose the connection to your FLEX? Try making a CAT5 choke for the Flex to PC interconnect cable. Take as many turns  as you can and pass them around and through a larger core. One other thing to consider - if you connect your devices through a hub or switch, try replacing it with another. It might be the active device that is inviting RF into your PC.

DrTeeth

@ WA2SQQ
Thanks for your optimism! It is well needed. I have bought some big enough toroids of type 31 material to make some nice chokes.

Ian GM4KLN

Excellent thread, thanks to all contributors!
I am optimising my 6300 based station which is 99.99%  for 50MHz (JT modes and CW): just seeking advice on whether the type 31 cores are still the optimum solution at 6m?
No specific issues - just trying to make the quietest possible environment for weak-signal work. 
tnx
73, Ian 

Steve G1XOW

Ian,

this is a very good starting point. "How to build a quiet station"

https://www.dropbox.com/s/kffp92esffo3zy5/How%20to%20Build%20a%20Quiet%20Station%20V2.pdf

Ian GM4KLN

thanks Steve, yes it is: I was just not sure if type 31 is the optimum for 6m, before I invest some £££ 

DrTeeth

Ian, I do not know the specs, but have a look at Type 43 ferrite materials.

Varistor

Mix 31 is specifically optimized for low frequencies, i.e. 10 MHz and below. Mix 43 is optimized for higher frequencies, but there likely is even better one for 6 m. Go to the Fair Rite site and look at their online catalog that shows the impedance of different mix types at various frequencies. Note that I would recommend you stack different types to build yourself a choke that covers everything from 160 to 6 m.

Ian GM4KLN

Steve, Guy, Rudy: thanks comments and advice. 
glancing through, 43 seems the best compromise on 50MHz, as 61 is 200MHz+ range..but will research deeper to confirm. 
73, Ian