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wrote:
Hello all!

I am working on a 2 meter (146 MHz) radio kit, and I am faced with
the need to adjust various coils and transformers in it. The
directions point out which ones can be adjusted with a metal tool,
and which ones really need a non-metallic tool. My first non-
metallic tool was a cheap plastic flat-blade screwdriver meant for
adjusting trimpots. It started out OK but the tip quickly got
chewed up and it started slipping. So, I get out the regular
(metal) screwdriver set, and managed to crack one of the cores with
my enthusiasm...

I have a new coil on the way and now I am looking at real, official
alignment tools. Basically, I see pure plastic tools of varying
materials, tools that are a metal core covered in plastic, and
some fancy ceramic ones. I'm pretty sure I don't want the ones
with a metal core. The plastic ones are inexpensive. The ceramic
ones sound like they would be more robust, but they also might be
more brittle. My immediate need is for a small flat-blade tip
about 1.5 to 2 mm wide, and a larger flat-blade tip about 4 to
6 mm wide. It seems like you can get a better deal on sets of
tools, which is fine, as long as it has the ones I need. In the
future I might be using them on other two-way radios, for sure
from 450 MHz down to 50 MHz, and then possibly on some radios
below 30 MHz. I don't anticipate using them much on AM or FM
broadcast sets, or television sets.

Are there any particular brands or features that are recommended,
or unfavored? Any sets that are particularly good for this
application? (I like the idea of the ceramic ones, but if they
break a lot they may not be worth the cost.)

Thanks for your help!

Matt Roberds

Cores break because of radial, outward force. A hex tool that fits
exactly exerts most of the force to rotate the core. If the tool is
ever so slightly too small or rounded, it will apply considerable
force to expand the core...at the weakest part of the core.

I've had some success with metal allen wrenches. Don't remember whether
it was SAE or Metric. Heat the coil slightly and loosen the core
with the allen wrench. Then adjust it with the plastic tool.

If you're talking about cores with a slot in the top, you have the same
problem with a flat-blade tool. You want it to fill the slot. Forces
go up rapidly as the tool gets smaller relative to the slot.
mike

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