Golborne Vintage Radio

Hello All!

I found a need for a ferrite core adjustment tool. It has to be the same size as a 1/10 inch or 2.5mm hex (Allen) key. None of my ceramic tools fitted and all my Allen keys are made of ferrous metal. Fortunately I have a 3d printer (Ender 3 Pro) and found a downloadable design on Thingyverse:

https://www.thingiverse.com/thing:5342615

I downloaded the 100mm long one with handle (2.5mm-Allenx100.stl). sliced it with Cura and printed the result with PLA filament. The outcome is not perfect, possibly due to my imperfect heated bed height adjustment, but it fits the cores nicely and is strong enough for the job. I imagine that it would break before a core would. One of the nice features is that it's long enough for deeply recessed cores.

I daresay that someone more skillful than me could design similar tools to fit other cores.

I hope this is useful to someone and apologise if I'm teaching my grandmother to suck eggs.

I filed my hex trimming tool from a plastic knitting needle, laborious.
I use a brass strip on those slotted all the way through cores as a chisel point splits them making removal very difficult. It has to be removed repeatedly when you think you have found the peak as it affects the tuning slightly.

I share your frustration. I have a set of cheap chinesium ceramic trimming tools and they either aren't long enough or aren't the right shape. On the plus side, at least they break more often than the thing I'm trying to adjust.

Incidentally, should anybody without a 3d printer want one of these, I'd be happy to print and send them out for the cost of postage. At least for, say, the next six months. I imagine, though, that most of you are already equipped.

I suspect many of us have the traditional plastic hex ended trim tools. About 5" long with a hex section on each end. One end is backed by an enlarged round section for ease of use. The other end is backed by a reduced diameter round section so it can reach through an upper core to adjust a lower one.

I've found two in a drawer, one red, the other blue. Both from RS Components. Must be several decades old.

They still supply them: https://uk.rs-online.com/web/p/trimmer-tools/0543147

(15-01-2025, 09:06 AM)ppppenguin Wrote: [ -> ]I suspect many of us have the traditional plastic hex ended trim tools.

I suspect you're right.

Where I used to repair vhf uhf transceivers, I had one with a ferrite core glued on one end and an aluminium one the other.
Useful on tx power amps by placing near stripline when investigating instability or tuning difgiculties.
Both had a piece of heatshrink tube as insulation.
Shorting a small piece of aluminium from a 28V 30A supply to earth could be rather interseting.
Rob