Always forward.

I haven’t forgotten of my little corner of the internet.  Things are busy.  I’ve constructed two band pass filters based on the article here:

http://www.arrl.org/files/file/Technology/tis/info/pdf/8809017.pdf

…and cribbing notes from a QRPSchool video:

http://qrpschool.com/portable-ops/band-pass-filters-for-qrm/

BLUF – mine don’t work.

My first, immediate observation, is that trying to get 48 turns on a T-48 core is a goddamn no-go.  I found an online calculator and re-ran the numbers on a larger toroid.  Pictures of my failed attempts may be posted at a later time.  Additional observations from the EE I had check my work:

The metal project box may act like a faraday cage.  RF is like voodoo, and my plastic boxes may not provide enough isolation.

My boxes were built according to the schematic in the article.  The actual filters are constructed differently – maybe.  All the L1 components share the same positive and ground connection.

My next attempt will be as close to exact duplication as possible, metal enclosure and foil PCB.

Advertisements

Get in on the discussion...

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: