Re: Question about the couplers

Mark Bauman

Hello Marco,

I have an experimental SAL amplifier module that has lower gain and improved IMD response that I can send you to see if that improves your situation. This module also has a header that you can use to add an external filter if necessary.

If you would like to try this module, please send an email with your shipping information to me at the following address: kb7gf at (replace the "at" with the @ symbol).


Mark KB7GF

On Sun, Sep 5, 2021 at 12:08 PM Marco Steiner <marco@...> wrote:

Sorry, the first link is invalid.


Here is a better one:



The first part is real, the second is full of intermodulation products.




Von: <> Im Auftrag von Marco Steiner
Gesendet: Sonntag, 5. September 2021 20:34
Betreff: [sharedapexloop] Question about the couplers


Hello Apex friends!


We have severe problems with the Apex-30 here in Germany due to intermodulation interference.

We don't have these problems when using an Apex-12.

Can it make sense to reduce the ferrites of the couplers on the Apex-30?

How does that work?

The opposite can be seen with the Apex-12, which brings relatively little signal strength.

Does it make sense here to increase the number of ferrites in the couplers?


Here is a comparison of Apex-12 and Apex-30:



Best regards



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