for my saa2n i have cal standards with plugs (male connector) .. but i wanted also female (so i can calibrate at cable end with a plug without double female needed)
so i took 3 N sockets .. one with a short .. one with an open .. and third got 2x 100 Ohms SMD resistors in parallel (centre pin shorted on all three to exact same length)
works good to over 3 ghz :-)
dg9bfc sigi
adding a "keyring" to secure them against getting lost
Am 21.03.2025 um 18:21 schrieb W0LEV via groups.io:
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QUOTE: ....a DIY fixture can be made using a female SMA connector with its
centre conductor sawn to the same level as the dielectric. .....
***
You can buy such a connector with no need to clip off the tip. They are
known as launchers and instead of the cylindrical tip, contain a short
ribbon connector meant to be directly soldered to a microstrip trace.
Dave - W?LEV
On Fri, Mar 21, 2025 at 7:30?AM biastee via groups.io <biastee=
[email protected]> wrote:
On Mon, Mar 17, 2025 at 03:22 PM, W0LEV wrote:
best "amateur" fixture is to solder cal. standards and test items to the
butt end of an SMA female connector - WITH ABSOLUTELY NO LEADS.
Indeed, the HP16092A is the butt end of an APC-7 connector, with just 3mm
of the centre conductor protruding beyond the insulator. It has an
advertised max freq of 500 MHz.
I agree with Dave that a DIY fixture can be made using a female SMA
connector with its centre conductor sawn to the same level as the
dielectric. Then, a plastic bulldog clip (similar to one in the photo of
the S21 fixture) can be used to clamp the chip component down.
I have measured a 89 nH inductor (6.5 turn, ID2.9mm) using the 1st type of
fixture (fixt s11.jpg). The fixture is calibrated using a 1206 size 50ohm
chip, and a brass shorting bar. Using the nanoVna V2+, the S11 from 10 to
1000 MHz (s11.jpg). The self-resonance is above 1000 MHz. The trace stays
inside the chart. The Q can be calculated from the impedance = R+jX at
different freqs.
According to HP/KS, the VNA has poor accuracy when the S11 trace is near
the perimeter. Hence, I also measured the same inductor using the S21
method in a microstrip fixture (fixt s21.jpg). A plastic bulldog clip is
used to clamp the inductor to the PCB. The fixture is calibrated bridging
the microstrip gap with a brass bar (thru). The measured and modeled S21
points a parasitic cap of 0.16 pF (s21_gra.jpg)
