Topic: Ferrites for H-Field

[Silversword]

Hi All,

Has anyone tried to add clip on ferrite clip ons to the input leads from the ferrite antennas just before the amplifier?  Wonder if this would help or hinder the local interference to the amplifier?  Just an idea as ferrites has reduced some other RF interference on my APRS system. Would it block the good lightning RF too??

Any thoughts?

Regards,

--Stan Y.
   Maui, Hawaii

[miraculon]

Stan,

I bought some special "low frequency" ferrites a while back (<1MHz). Even with multiple ferrrites per line, they were no magic fix. Typical clamp-on ferrites are higher frequency than the ones I have and they are not likely to help. I think that the frequency range of interest is just too low for them to be effective. The good news is that they didn't seem to hurt performance any.

I added them to the amplifier-to-controller lines, power supply, GPS antenna. I think that I might have tried them on my old Green unit at the input lines from the antennas, but I don't remember any improvement.

As long as the ferrites are common-mode to both amplifier input wires I would think that it shouldn't hurt anything. Don't put it around just the "signal" input antenna cable alone. Then there could be an adverse affect.

Greg H.

[Silversword]

Thanks Greg for the reply and recommendations.

I was thinking about getting something like these, http://www.amazon.com/UF-50B-Noise-Suppressor-Ferrite-Filters/dp/B009ENG6TI from Amazon and see what happens.

Do you have other recommendations for clip on ferrites (low frequency) that might be better to filter out RF rubbish that might be higher in frequency that might cause some interferences?

Also maybe looping it around once in the same ferrite, instead of being straight through.

I was thinking of putting it on the shielded AF cable that I am using on the two that are coming from the 300 mm ferrite cores that I am using and see what happens Just before it enters the amplifier box that I am using...

Regards,

--Stan Y.
   Maui, Hawaii
 

[miraculon]

These are the ones that I used from Intermark. They are now calling themselves Kitagawa.

http://kgs-ind.com/products/emc/emi-ferrite-emi-ferrite-cores/low-frequency-khz-ferrite-cores/

The RFC/MRFC "KHz" range ones are what I tried.

A 2nd pass through the ferrite is a good old trick, sure you could try that.

Greg H.

[Silversword]

Thanks Greg for the reply and info on the low freq ferrites.

Now to find a vender that supplies these ferrites.  Guess that I would need at least four of them for my system and see what happens.

Regards,

--Stan Y.
   Maui, Hawaii

[miraculon]

I sent you a PM.

Greg H.

[Silversword]

Greg,

Got your PM and I replied.

Regards,

--Stan Y.
   Maui, Hawaii

[Silversword]

Hi All,

Finally got 4 Low Frequency RFC-8MA ferrite clamps installed to my H-Field system.  Two of them at the input to the amplifiers, one on the Shield CAT cable just before going into the Controller and the other one on the GPS cable just before going into the Controller. They seem to help reducing some of my interferences coming into my system.

I did one loop around at each of the cables with the exception of the CAT Cable.

Here is a resource for Low Frequency ferrite clamps:

http://kgs-ind.com/products/emc/emi-ferrite-emi-ferrite-cores/low-frequency-khz-ferrite

Thanks Greg for this information and assistance.

Regards,

--Stan Y.
   Maui, Hawaii