"K7ITM" wrote in message
...
On Apr 23, 6:01 pm, "Joel Koltner"
wrote:
Are there some vendors of readily available (stock) inductors that have
reasonably good Q's (100) throughout the HF band?

I'm familiar with something like the Coilcraft "maxi springs"
(http://coilcraft.com/maxi.cfm), and while they hit Q's of 100 by 30MHz,
I'd
really like something that's already there by 3MHz or less (...and still
have
a self-resonant frequency of 30MHz). This seems quite doable simply by
making a larger coil with thicker wire, I'd just like to find a place that
offers such inductors off-the-shelf rather than having to wind my own.
Inductance in the ballpark of 1-10uH would be good, although it's not
critical.

The goal here is to try out making some adjustable notch filters for a
receiver (by switching L's and C's in and out, like antenna tuners do).
Hence, high Q is important, but power handling capability isn't so much,
and
anything smaller than a breadbox is fine size-wise.

Thanks,
---Joel

(snip some of Tom's good stuff)

"It used to be that you could buy a supply of AirDux or equivalent coil
stock, and just cut off the number of turns you needed for some
specific inductance. My answer to that these days is to thread some
plastic tube on a lathe, and have a few different thread pitches
around, then just wind magnet wire down in the groove to get what I
need "on demand." It's easy to do the winding and makes a nice,
uniform-looking coil. I've used that technique to make sets of coils
for reasonably sharp cutoff bandpass, lowpass and highpass filters
with very low distortion that I've used to characterize the distortion
performance of amplifiers and the like."

"Sorry that I don't have a better source of ready-made coils...maybe
someone else has."

Cheers,
Tom


Apparently, AirDux is still available:

http://www.airdux.com/

73,
John