Pico SWR

[alfian]

How to calibrate Pico SWR?

[UR5FFR]

1. Connect Pico SWR to computer, run software, select com-port and press open
2. Press "Calibration" button
3. Select "XTal frequency" tab. If you have frequency meter - connect it to Pico SWR out and measure frequency. If you haven't it - use crystal frequency. Enter frequency value in Hz. Press "Ok"
4. Select "Detector slope" tab. Disconnect load and press "Run". After calibration done press "Save"

[alfian]

that's very helpful. I will try to fix. thank you
I'm still confused with T1. how to make it ... is it enough with the toroid wrapped around the cable

[UR5FFR]

Use next construction

14061_1.gif (11.35 KiB) Viewed 12726 times

Up wires to bridge R1R8R9, bottom - to ground and C17

[alfian]

This construction that I made

[UR5FFR]

Yes, it's ok. Don't mismatch wire connection and all working as expected

[alfian]

Results from circuit measurements. Not flat SWR 1: 1. whereas at the output output of 50 ohms. Statistik freq1,000,000-end 200,000,000, does this work well ...?

[UR5FFR]

Are your sure about 50R load? My 50R load - two smd 100R in parellel in SMA socket

Can you check voltage at BF998 drain? It must be in range 2.2v..2.8v
If you have thin 50R coaxial cable 2mm diameter try to make T1 from it.

[alfian]

load 50R. but my TR 1 uses bf980 ... does this cause different results. because TR 1 is rare

[UR5FFR]

BF998 is very cheap transistor widely available. I haven't experience with BF980, but I think that all must be working same as with BF998. Anyway you need check voltage at drain - it must be in range 2.2v..2.8v.