The datasheet claims 0.3dB insertion loss, -19.3dB coupling (forward), and 50dB
directivity at 1MHz. Right now, I'm interested in results at 5MHz, but that's
-the nearest point fro m the spec.
+the nearest point from the spec.
I've no hope of measuring insertion loss to 0.3dB, so lets look at directivity
and coupling instead. Tools available are an FT817, and my W7ZOI [powermeter]().
power.
To measure coupling:
+
1. Terminate the *cpl* port in 50R
2. Connect the rig to the *in* port
3. Connect the power meter to the *out* port
the power meter to *cpl* and record the reading, that's coupling.
To measure directivity:
+
1. Terminate the *out* port in 50R
2. Connect the rig to the *in* port
3. Connect the power meter to the *cpl* port
0dBm forward power on the meter
5. Reverse the *in* and *out* ports and measure power, that's directivity.
-+----------------------------------------------------+
+
| Frequency [MHz] | Coupling [dB] | Directivity [db] |
-+----------------------------------------------------+
+|-----------------|---------------|------------------|
| 1.80 | -18 | -44 |
| 5.36 | -18 | -40 |
| 10.11 | -17 | -38 |
| 50.00 | -17 | -25 |
| 145.00 | -18 | -14 |
| 435.00 | -22 | -8 |
-+----------------------------------------------------+
+
[ZDC-20-3]: /notes/Characterising_a_coupler/ZDC-20-3.pdf
[powermeter]: /notes/W7ZOI_Power_Meter