[Central-Electronics] Fwd: Re: 6550

[Gordon]

Jim,
   I found a Choke that is 22uH and resonant around 40mhz and rated at 1Amp
I guess I'll try that one.  ( Actually, I went to mouser and ordered a 
whole selection of 22uH Inductors..LOL )
   I do Not have a meter like that.
I have one that measures Inductance, one that does capacitance, one that 
does Resistance and all the normal Test Equipment including a Spectrum 
Analyzer, Scope, Freq Counter and Generator.
73,
Gordon

On 7/25/2013 2:18 PM, Jim Candela wrote:
> Gordon,
>
>      I wonder if you have an impedance meter? Something like an Autek RF1?
>
> http://www.autekresearch.com/rf1.htm
>
>
>
>     These will measure RF components at whatever frequency you choose. Lots of folks miss the point that at RF, a part that is rated at 1 Khz is likely to be way different. For example, a .01 uf disc capacitor wrapped around my grid dip meter coil with the leads twisted together in a loop, will go through series resonance at around 7 Mhz. So above the resonant point (series resonance) this thing looks like an inductor. For a parallel resonance situation an inductor looks like a capacitor when above the resonant frequency.
>
> Another possibility is a grid dip meter. With a grid dipper you can wind an air core coil, and with a known capacitance make a parallel L-C circuit. Then use the Grid dipper to find the resonant point(s). For example a 22 uh inductor should resonant with a 100 pf capacitor at about 3.4 Mhz.
>
>    As to the size, the 100V puts out 100 watts into 50 ohms, so that would be 71 volts RMS. This inductor therefore should not be tiny. Perhaps wind the coil as several smaller coils in series to minimize the turn to turn capacitance that will cause a coil self resonance at a higher frequency. Maybe try 10 turns #28, 1/4" dia, then move over 1/8" or 1/4" and do it again two or three times. Then see where you are. You could get more scientific of course, but with a little instrumentation, and sweat you can likely get there without puling out the credit card.
>
> Jim
> WD5JKO
>
>
>