As others have noted, it probably won't be quite the same, but may
work. But from the numbers you gave, I guess the specified core must
be a T-20-2, no? Whatever the core, you should be able to get an
estimate of the Q that the toroid form will give you (for example, see
http://www.amidoncorp.com/aai_ironpowdercores.htm), and you can make
an estimate of the Q you'll get at the same freq with an air-wound
coil, just to be sure you're in the ballpark. For coils about as long
as their diameter, the Q is roughly 100*(diam,inches)*sqrt(f,MHz)
There are air-core coil programs around that will estimate the Q more
accurately, and the self-resonant frequency as well...Reg Edwards has
one, for example. -- If I guessed right on the toroid core, you'd
probably see a Q around 120-140 in the 5-10MHz region for your coil,
and you'd have to use an air core coil roughly half an inch diameter
to get that. (My coil program tells me that 11 turns of #22AWG 3/8"
ID and a bit under 1/2" long will give you the inductance you want, at
a Qu of about 150.)

Cheers,
Tom

"J Shrum" wrote in message ...
Greetings,
As a newbie to RF building, I have noticed that some instructions tell you
how to wind the coil, and they give you the value of the coild as well...

In my scenario, the inductor in question is a .72uhy which the directions
state to use 17 turns of #30 around a toroid. I don't have the requested
toroid, so I was just going to wind a .72uhy inductor around a 1/2W 5M ohm
resistor.

This will just the same right? Whether its a .72 on a toroid, or a .72 on a
resistor... they are both the same, correct?

Thanks for your help.
James Shrum - KC9FFX