BALUN BACKPLANE PLANS FOR "DJ0IP HYBRID BALUN"

Commercial Baluns are always built into an enclosure, completely sealed such that air cannot escape.  This also prevents heat from escaping, which can lead to unwanted heating of the balun.

In his excellent paper on  A New Choke Cookbook for the 160–10M Bands,  K9YC writes:

Avoid Putting Transmitting Chokes In Enclosures – it greatly reduces the transfer of heat to ambient air, and can easily cause destructive overheating. In general, it’s best to leave the choke exposed to air, weather-proofing connections as needed. (snip) . . . any enclosure for a transmitting choke should be ventilated.

I seldom build my baluns into an enclosure.  Instead, I simply mount the Toroid(s) to a backplane built from Expxy Board (FR4) or Plexiglas, insulate all connections with heat-shrink tubing and/or liquid electrical tape, and sometimes coat the Amidon Toroids with liquid electrical tape.  Or, I use Ferroxcube Toroids that already have a thin layer of Epoxy paint over the Ferrite.

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