Index
26.

Protecting the filter from aging.

When the filter needs no more adjustment or changing, it is time to conserve the good properties. Use CRC 2-26 or 3-36 or 5-56 as an oxide-remover and re-oxidation-preventer.
I have used CRC2-26 over the years, and discovered, that it dissolves surface oxidation etc. exactly like said on the can. You will find the dissolved material as green "drab" at the bottom of the sprayed apparatus.
Do NOT apply CRC to variable condensers, close-wound coils and motor-brushes, as it is very hygroscopic.
It works very well in plugs/connectors, potentiometers, switches, and as a light lubrication for very light running bearings etc. It drives moist out of the way, cleans the surface, and protects it from further corrosion, enhancing contacts.

After some time (say one month) most of the CRC has disappeared, leaving behind a very thin layer if oil-like substance on all surfaces, shutting them off from the air, and preventing further oxidation. In a closed environment (like the cavities), it should not be nessasery, to apply it again for a few years.

27 Applying the anti-oxidant:

27.1 Drill small holes (just big enough to pass the spray-tube) in the middle of each sidelid and cavity-bottom for spraying.

27.2 Drill a 3mm hole right in one lower corner of each cavity-sidelid for draining. Drill them close to the bottom-plate "G", all on the same side of the cavities (f.i. the "Ant"-side).

27.3 Spray generously on the central conductor, coupling links, and all internal walls.

27.4 Spray the inside of each central conductor through the hole in the top-compartment of each cavity.

27.5 Turn the filter around in all positions to roll the fluid to all surfaces.

27.6 Place the filter on absorbing paper, and let it drain for a few days. Tilt the filter in different directions to drain easier.

27.7 After a few days, you could apply and drain CRC2-26 for a second time if you want.

27.8 Then check the filter-performance. It should not be altered.

As you see, it is a lot of work to build and adjust the filter, but it is interesting and fullfilling. After all, the technics are not used much in the amateur-world. I could not find much theory about it. I hope to have at least given good info, about what mechanical and RF-properties are important with respect to good performance, also after years of service, and what is important for correct adjustment an measurement of the filter.

73's form Nico, pa0nhc.

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