[TowerTalk] Relay Box Measurements

[Jim Lux]

On 8/26/12 10:27 AM, 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.
>


That was sort of my thinking, but one never knows..  I think in this 
kind of situation, what we're really in interested is S21 in on/off 
position, and S2x to other ports.