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Construction Materials
Specifics and Sources

We will be happy to list alternate sources of materials, particularly sources in Europe or Asia to serve those who find it difficult or expensive to use USA sources. Sources and web links below list thus far known reliable providers of specified materials. Auction sites such as Ebay often have these materials, but not constantly. The reader will need to take care they obtain the specified materials.

This site specifies #2 powdered iron toroids for use in its isolation transformers. If you buy from an auction site, or are pulling a core from the toroid junk box, you need to be sure that the toroid(s) you use are in fact #2 powdered iron. One flat surface of #2 powdered iron toroids is clear-coated, appearing as the natural dark gray of the core material. The other surfaces are painted a somewhat brownish red. The illustration below shows the three referenced sizes, T400A-2 or T400-2D** (upper), T300A-2 or T300-2D** (lower left), T300-2 (lower right).

To verify which #2 powdered iron toroid you have in hand, measure the outside and inside diameters, and the cylinder height (thickness). T300 toroids have an outside diameter of 3 inches (78 mm), an inside diameter of 1 15/16 inches (49 mm) and a cylinder height of 1/2 inch (13 mm) or 1 inch (24 mm). A T400A-2 (T400-2D) toroid has an outside diameter of 4 inches (102 mm), an inside diameter of 2 1/4 inches (58 mm) and a cylinder height of 1 1/4 inches (32 mm). There may be small variations in these dimensions, less than 1/16 inch or 1 mm.

** Do not wind an isolation transformer on other than specified size and composition toroids. **

** Micrometals designations for Amidon's T400A-2 and T300A-2. Amidon and Micrometals have the same designation for the T300-2

1:1 Isolation Transformer and FCP Parts List

Amidon T300A-2, T300-2, T400A-2 #2 powdered iron toroid,  Amidon, table of #2 Iron Powder Toroids

Micrometals T300-2D, T300-2, T400-2D #2 powdered iron toroids,  HEROS Technology Ltd (UK), table of all Iron Powder material Toroids at bottom of page.

Micrometals T300-2D, T400-2D, T300-2 can often be found on eBay. A pair of Amidon or Micrometals T300-2 can be taped together for the regular core. Amidon and Micrometals #2 powdered iron cores can be mixed in an isolation transformer constructed with multiple cores.

Double polyimide insulated wire #14 AWG,  TheWireMan #635

#12 AWG standard wall PTFE** tubing,  Amidon, PTFE Tubing

For wire and tubing lengths for PTFE tubing and double polyimide wire see the isolation transformer table at To order, remember to use the "total" lengths in the transformer table, based on double the turns of the bifilar winding length.

** PTFE is often called by the brand name Teflon®, the registered trademark for the PTFE product line of E.I. du Pont.

Carlon 4 x 4 x 2 enclosure (for isolation transformer) with cover gasket, Carlon E989NNJ-CAR, or equivalent, at local home improvement stores.

170 feet of bare solid #12 copper wire for the FCP,  TheWireMan #538. For half the price of an equal length of solid #12 wire furnished bare, one can usually purchase a spool of solid #12 THHN electrical wire from a home improvement store, and strip the insulation with a dull pocket knife for bare wire.

160/80 Dual-banding Project, Parts List and Sources

These items are sourced and discussed in detail in the section on 160+80 dual-banding at

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