The purpose of a goniometer or variometer in transmitting

[Opcom]

I ended up with some variometers/goniometers, and don't find much on them except old receivers. Really old receivers.

Among them is what looks to my ignorant eye like a large Millen plug-in transmitting coil similar to BC-610 size and with the ceramic bar-plug setup of banana plugs, but it's maybe for 6 meters, or not enough turns for 10 Meters anyway.

Instead of  the usual two air-wound coils with space in the center for a lever-mounted coupling coil, this is a long ceramic form about 2.5" diameter with maybe 3 turns on each side.

Instead of a space for the output link, this form is solid and has a smaller ceramic form in the middle, inside the form, with several turns on it, which can be rotated - so it looks like a strange high powered push-pull variometer. There are no markings.

Would it be right to think that there's no reason this arrangement would be any different, from a results standpoint, than a regular moving link coupling coil? It's just wierd because of the VHF appearance of that when I am thinking about the old stuff. I know I should be posting pictures of it, just have not had time to take any. No markings at all on it.

[W2JBL]

It's a variable inductor, not a coupling unit. Was used in the PA tank circuit of the ART-13.

[kb3ouk]

The GO-9 transmitter i have uses one in the oscillator instead of a cap for frequency tuning. The outer coil is tapped for different frequency ranges.

[W7TFO]

Many hams have lost sight of the advantages of varying the L, rather than the C of a resonant circuit.

One of those advantages is when rotated, a vario can represent in- or out- of phase coils, therefore can subtract or add L over the median point, unlike a variable cap.

Variometers were an answer before roller inductors were widespread.

73DG

[W3SLK]

Looking at the different 'Eastern European' parts site, it seems the Russians used variometers more so than those on this side of the world!