[ARC5] Making Stable Inductors for 2 MHz

[J. Forster]

> The coils are fairly easily done. As I said, all it really requires
> is a form made of stable material, and then some careful winding.
> Although ceramic coil forms are usually best, those used in the VF-1
> are phenolic.

Do you know if it makes much difference whether the inding is a single
layer solenoid, or if it needs to be like IF transformers, as long as the
self-resonant frequency is high enough?

> Toroid-cored coils are a bit more problematic since some ferrite
> material is not particularly temperature-stable. However, others have
> made them work quite well, especially when using solid-state active
> devices (FETs).

>From what I can see, most are not that good.

>> I really would rather stay away from a DDS solution, for a number of
>> reasons, not the least of which is chips going unobtanium. Also, to
>> shape the envelope correctly requires a bunch of other stuff.
>
> The solid-state VFOs I have mentioned are NOT DDS types: they simply
> use an FET as the active device, and possibly another or a bipolar
> transistor, as a buffer.

OK. TY.

> Otherwise, they are identical with tube-based VFOs.
>
> The main idea behind and the result of using an FET is that the far
> lower power (voltage and current) required, and the lack of need for
> filament (heat) vastly reduces any thermal drift.

Understoof. I want to avoid any temperature control, hence the +/- 10 C
spec. I think, since the thing will eventually be in the center of a
50,000 ton ship, the temperature will be pretty stable.

> That one in Electric Radio magazine I mentioned is of such. Its drift
> characteristics are by no means the best achieveable, but are quite
> adequate for your needs.
>
> Ken Gordon W7EKB

Looks like it.

Thanks very much,

-John

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