[RFI] Experience with RF-INQUIRY Hi-Q Chokes?

[Christian Buenger]

Hi rfi-experts,

just came across an advertisement of a common-mode choke produced by 
RF-inquiry of Japan. They claim to provide at least 50 dB of reduction of 
common-mode-currents. There exists two versions. 250 W and 5 KW.

Has anybody experience with these things? I have some minor RFI problems 
here at home and they might be related to common mode. I already have a 
coil of coax below my beam (which is on top of the house). Can anybody 
confirm these 50 db? Sounds a lot to me.

I somehow have the feeling that inside that "Hi-Q Choke" there is only a 
piece of coax with some ferrite beads. Just a typical W2DU baluns on teflon 
coax which you get for 20 EUR here in DL. The RF-Inquiry ones cost about 
120-180 EUR (depending on power).

Unfortunately there is not much information about these products on the 
web. Can somebody here in the mailing list shed some light on this topic?

Another question. Can I use a W2DU 1:1 balun in my transmission line just 
right after the amp and expect some filtering of common mode currents on 
the coax cable? Would this help to "clean" up the coax? Or do I have to use 
2 baluns. One at the input and one at the output?

Thanks in advance!

73
Christian, DL6KAC
--
mailto:c.buenger at gmx.ch
fax2mail: +49 25 61 / 9 59 42 99 20