On 8/26/2012 1:27 PM, Jeff DePolo wrote:
>> when you do the measurements (using some form of VNA, I
>> presume), do you
>> cal with a set of standards with UHF connectors, or something else?
> You're better off using lab-grade test cables with constant impedance
> connectors (N, SMA, TNC, etc.) and a precision cal kit to do the cal, and
> then use a high-quality adapter to get to UHF to connect to the DUT. Unless
> you're dealing with short wavelengths, the added electrical length of the
> adapter (maybe 3/4"?) isn't appreciable (3/4" is only a little over half a
> degree at 10m), but if you're a purist you could always offset the complex Z
> accordingly (Smith Chart or electronic equivalent thereof). Insertion loss
> of a quality N to UHF adapter is negligible at HF.
For myself I'm really not interested in reaching lab grade accuracy.
If line loss is within a few tenths of a db of the manufacturers specs,
I'm happy. That lets me compare coax cables as well.
If I can find discontinuities within a few tenths I'm also happy.
My primary interests are SWR, finding resonance, and bandwidth.
Using the TDR function it's finding those discontinuities such as coax,
coax connector, or relay problems.
> --- Jeff WN3A
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