GRC/3030 Tank Coils

On this page you can follow the development of 2 sets of three replacement Tank Coils for use in “demilitarized” GRC-3030 rigs.

These, to Dutch an Belgian Hams well known transceivers were the Dutch successors for the WS-19. They were made by Van der Heem/Philips. When the sets became obsolete they were sold to the surplus traders. But before that happened, the sets were “demilitarized”. That meant the 3 tank coils were smashed and the PA tube removed, to be sure no one could transmit with these sets ever again.

Recently, after having seen my Paraset coils, I was asked by Louis ON5LBL if I could recreate these tank coils. And after studying the subject and making a drawing, I decided to give it a go. 

There is a discussion going on, whether these coils should have a adjustable core of some kind. So I will make a solution that provides a possibility to add a core afterwards.

I use the same material as used in the Mk-VII Paraset, Tufnol or Paxolin, a material based on phenolic resin.

July 5, 2019. Today I made a start by cutting the raw material from stock:

The raw tubes need to be polished. Just for the looks, I know.

Then, after putting measures on the tubes, the drilling can start. I use a divider tool to make the holes 90 degrees apart. First a 2 mm hole is drilled, than the hole is counter sunk at 4 mm.

July 7, 2019. Worked a bit more on the GRC-3030 tank coils.

Made a small, round chisel to cut the 1 mm thread and adjusted the lathe to cut with 1 mm space.

Put in the stubs after making a little tool to do so.

The first 2 are ready to be winded!

But before I start winding them, I will finish the other 4 coils.

July 20, 2019. Today I threaded the last two coils with the finest pitch: 0,6 mm, for loading them with 0,3 mm, 0,3 mm spaced. I also made the lids flat:

Next thing to do is remove some material from the edges to leave a rim of 2 mm.

(to be continued – watch this space!)