Hi Jim,
"Jim Thompson" wrote in = message news: snipped-for-privacy@4ax.com...
>=20
>>Jim Thomps>>> Is it possible to get a 1.2uH inductor that's still inductive at
>>> 600MHz ??
>>>=20
>>> ...Jim Thompson
>>
>>Sure. You do it using a coil wound as a tapered helix, with its point =
>>towards the high-frequency side, backed up with SMT coils of =
increasing=20
>inductance. It's done all the time in bias tees--I have one that's =
flat=20
>within about +-1 dB from 20 kHz to 30 GHz.
>>
>>It would be difficult to make an inductor that still looked like 1.2 =
uH=20
>at 600 MHz--it would resonate with 60 fF.
>>
>>Cheers,
>>
>>Phil Hobbs
>=20
> What I'm trying to implement, cheaply, is a crossover network for a
> coax splitter: corner at 10MHz, impedance 75 Ohms, but "well behaved"
> at 600MHz.
>=20
> (G-job ;-)
Another possibility is a ferrite toroid inductor/choke. I made one awhile back with 14 turns on a 0.230" dia toroid, which had a low freq. mu of 125. It looked like a 4.2 uH inductor at low = freqs. It resonated at 145 MHz, and at 1 GHz it looked like 0.3 pF in parallel with 2k ohms. =20
You would need fewer turns and would get a higher resonant freq. I would think. And you still get to wind something. :)
If you are concerned about the rejection at 600 MHz of the low-pass branch, you'll have to minimize the inductance of your shunt capacitor.
--=20 Regards, Howard snipped-for-privacy@ix.netcom.com