[Elecraft] BL3 Details: Common Mode Choke?

[Wayne Burdick]

Hi Steve,

Yes, the BL3 is a high-power common-mode choke. It is intended to remove
RFI from the coax shield, which is often a problem in portable stations,
especially if a laptop, mouse, keyboard, or other external gear is
involved. It can handle up to 100 W even at high SWR (i.e., when the whip
is off-resonance due to variables such as antenna height, soil type, and
radial configuration).

As you can see from the image on our web site, BNCs are used at both ends
for quick deployment. The enclosure is non-conductive (nylon).

73,
Wayne
N6KR


On Wed, Sep 2, 2026 at 1:44 PM Steve Lawrence via Elecraft <
elecraft at mailman.qth.net> wrote:

> Is the BL3 designed to work as a common mode choke?  Does it offer any
> impedance transformation like 50 ohms to 25 (or similar)?  Is it a balun or
> unun?
>
> Thanks
> Steve
> AA8AF
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