[600MRG] Measuring ESR

[John Andrews]

Frank,

All of my ideas involve spending money! A part of the question is what 
your application is for these capacitors. It's one thing to just weed 
out the best bypass caps for a given frequency range, and another if you 
are going to run real current through the cap. For bypasses, sub 1 Ohm 
readings probably aren't necessary. But for tuning networks with high 
circulating current, 0.1 Ohm may be a significant resistance.

Anyway, RF impedance bridges are nice for this. In the frequency range 
you mentioned, the General Radio 916AL and 516C bridges (antiques, both 
of 'em) are good. But a simple RF impedance bridge that has a 100 Ohm 
pot isn't going to give you much resolution at the low end.

Of course, network analyzers are probably the best approach, and we've 
come a long way since you had to have an HP beast that required 2 men to 
lift. The AIM4170 and AIM4300 single-port analyzers would be perfect. I 
have the 2-port version, the VNA2180, but that's overkill for component 
measurements. Some of the various other antenna analyzers would be OK, 
but I haven't done the research.

On the other hand, armed with a bunch of low ESR caps with known 
parameters, you could make some substitution measurements with a signal 
generator and a good RF voltmeter.

John, W1TAG

On 8/17/2015 9:27 PM, Frank Lotito wrote:
> Can someone refer me to a method for measuring the ESR of capacitors in the range of 0.001 to 0.100 microfarads, at a frequency of 500 KHz - 2000 KHz?  A bona-file laboratory grade network analyzer is out of the question for my pocket book.  The simple ESR measuring schemes found on the internet are recommended by the authors for capacitor values greater than one-microfarad.  The coaxial RF probe methods seem to have application for capacitor values smaller 1000 picofarads, and the measurement frequency is mid-UHF.  Thank you - Frank Lotito K3DZ / WH2XHA
>
> _______________________________________________
> 600MRG mailing list
> 600MRG at w7ekb.com
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>