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Sanken COS11D RF problem with A10


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Hello everybody.
I have several Sanken COS11D wired by a local audio shop for the Audio LTD A10 transmitters.
Now I found that sometimes when quick dropping the TX in someones pocket, I get very nasty high frequency RF noise.
When I take the TX out and get the cable of the COS11D away from the whip antenna, it goes away.
I could reproduce this by coiling up the cable once or twice, holding it parallel to the antenna and moving it towards it. "Works" everytime.
Its really bad when the TX is on high power, but also on low power it is noticeable.
This does not happen with my DPA6060s - I can wrap that cable around the antenna if I wanted to and no noise at all.

Has anybody had similar problems?
Maybe the COS11D is wired wrong, so the "RF immunity" of the D series that Sanken says it has does not work properly?
Anyone with knowledge on correct wiring for A10s and RF rejection?

Any help is appreciated!
Thank you

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Hi Mano,


From what we know here at Wendy's it could be one of two things or both:

  • It might depend on the age of your Sankens as the  Sanken COS11D mics have better RF shielding than the older Sanken COS11 mics. You will need to check to see if you have the 'D' variant to verify.
  • The shield which goes to pin one in the 3 pin Lemo has possibly not been grounded to the shell. It is not required but it does help a lot. We typically wire a Sanken COS11 by splitting the center shield in half and putting half with white to pin 1 and black to pin 3. The other half we make sure is in contact with the shell of the Lemo.

Hope this helps.



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  • 2 weeks later...

Thanks Nathan.

I made sure I have the "D" variant - my Cos11's are very new.


Thanks for the wiring tips. I will go back to the shop that wired them and at least I have something to discuss about.


Do you have a wiring scheme or more information on the correct wiring for maximum RF rejection?

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  • 3 months later...

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