External POWER/SWR meter
Experimenting with the power/swr meter on the PA PCB learned me that the harmonics still in the signal couldn't get me the SWR down to zero. So the POWER/SWR meter on the PCB I will use to secure the power and SWR before the filter, and make another POWER/SWR meter after the filter, to measure the Antenna performance.
So here are the measurements of this filter:
Dummy load connected to the outgoing connector (1500W).
Input from the FT-950 Voltage forward (V) Voltage backward (V) Reversed meter delta:
10 Watt input: 0.263 0.000 0.006
15 0.382 0.000 0.003
20 0.484 0.000 0.004
30 0.632 0.000 0.004
40 0.778 0.000 0.005
50 0.908 0.000 0.004
60 1.003 0.000 0.003
70 1.108 0.000 0.006
80 1.210 0.000 0.006
90 1.303 0.000 0.004
100 1.391 0.004 0.002
And vice versa
Dummy load connected to the outgoing connector (1500W).
10 Watt input: 0.269 0.000
15 0.379 0.000
20 0.480 0.000
30 0.628 0.000
40 0.773 0.000
50 0.904 0.000
60 1.000 0.000
70 1.102 0.000
80 1.204 0.000
90 1.299 0.000
100 1.393 0.004
The output voltage is dependent of the frequency.
100W input gives: corrected for input power (100W)
160m 1.460 V 98W 1.490 V
80m 1.454 97W 1.499
40m 1.433 95W 1.508
30m 1.434 96W 1.494
20m 1.401 93W 1.506
17m 1.421 95W 1.496
15m 1.450 99W 1.467
12m 1.425 95W 1.500
10m 1.482 100W 1.482
6m 1.573 100W 1.573
Accuracy within 2 percent. I am satisfied with this.
So, at 100W input, the forward voltage is about 1.4 Volt. So at 400W it will be about 2.8 Volt. So the voltage level is very well suited to measure with the Arduino (up to 5 volt max). The meter is very robust and can handle up to 1 kWatt.
This meter is giving a little bit more voltage than the one on the PCB of the PA because the voltage divider is not 0.5, but 0.55. So 10% more voltage. At 400W it brings 3.08 volt (10% more than the meter on the PCB.
I changed the setup a little bit. The internal SWR meter is connected before the filter, and behind the filter the external meter.
I noticed that the power out of the filter was significantly lower that before. About 50Watts less.
I also noticed that the swr of the external filter was not 1:1. So work to do.
First I measured the external PWR/SWR meter with my vector analyzer. It showed some inductive impedance. I can image that because I built is with very low parasitic capacitance, the inductance was not compensated enough. So I experimented with a few capacitors, and the best results was a capacitor of 47pF parallel over the input of the meter (in the metal box). The result was indeed a higher power at the output.
I also noticed that the SWR of the internal meter before the filter was bad. 1:1.8 and higher. I thought that the impedance of the filter was maybe not good. The next thing to experiment was to look at the impedance of the filter- meter train.
Also with the vector analyzer. On 14MHz I saw that the lowest SWR was not at 14.100 but just under 14.000. Not ok thus.
I got it back in the band with a 50Pf capacitor parallel at the input of the filter. But under the line I was not satisfied with the setup where the internal SWR meter is put before the filter. So I changed it back to the setup PA-Filter-PWR/SWR meter (internal), and I left the external meter in the train to the Dummy load.
Additional capacitors in the external meter and the 20M filter are still in. Now I want the power measurements:
All these measurements are not corrected for the fact that the FT-950 is not 100% correct. Sometimes at 100Watt -10% difference.
Band Power in Power out on the internal meter V-external meter (foreward-reflected in Volts) SWR int SWR ext
1.8 5 81 1.30 0.01 1.15 1.02
20 250 2.45 0.018 1.09 1.02
50 370 3.03 0.022 1.08 1.02
70 425 3.23 0.023 1.10 1.02
85 450 3.35 0.024 1.09 1.02
100 480 3.45 0.025 1.08 1.02
3.5 5 79 1.28 0.010 1.16 1.02
20 265 2.50 0.019 1.11 1.02
50 390 2.80 0.025 1.11 1.02
70 440 3.30 0.026 1.11 1.02
85 460 3.37 0.034 1.11 1.02
100 485 3.47 0.045 1.11 1.03
7 5 70 1.17 0.010 1.17 1.02
20 262 2.45 0.039 1.16 1.03
50 402 3.10 0.053 1.18 1.04
70 450 3.30 0.071 1.18 1.04
85 480 3.40 0.085 1.19 1.05
100 510 3.48 0.111 1.20 1.07
10 5 67 1.14 0.067 1.24 1.13
20 270 2.49 0.077 1.25 1.06
50 420 3.15 0.143 1.26 1.10
70 470 3.36 0.173 1.28 1.11
85 500 3.45 0.199 1.28 1.12
100 530 3.60 0.220 1.29 1.13
14 5 61 1.06 0.017 1.31 1.03
20 263 2.45 0.160 1.33 1.14
50 440 3.26 0.279 1.33 1.19
70 495 3.46 0.311 1.35 1.20
85 525 3.58 0.338 1.35 1.21
100 550 3.66 0.355 1.36 1.22
18 5 47 0.90 0.022 1.35 1.05
20 201 2.12 0.185 1.36 1.19
50 373 3.00 0.332 1.38 1.25
70 436 3.24 0.392 1.4 1.26
85 480 3.43 0.440 1.4 1.29
100 517 3.55 0.485 1.43 1.32
21 5 53 0.98 0.0.45 1.38 1.10
20 218 2.24 0.270 1.42 1.27
50 375 3.02 0.428 1.49 1.33
70 400 3.10 0.443 1.50 1.33
85 415 3.14 0.454 1.50 1.34
100 422 3.18 0.470 1.52 1.35
24.5 5 39 0.81 0.035 1.35 1.09
50 347 2.85 0.456 1.39 1.39
100 433 3.20 0.547 1.45 1.41
28 5 46 0.91 0.073 1.34 1.17
50 395 3.10 0.610 1.33 1.49
100 503 3.55 0.735 1.37 1.52
50 5 28 0.70 0.145 1.75 1.53 50 345 3.06 1.068 1.84 2.07
100 Arduino crashed !!!!!!!!!!!!!!!!!!!
Well, my conclusion with working with two SWR-meters is that I don't actually need two of them. So I have now a spare SWR meter for high power in my junkbox,......and I will go further with one SWR meter, the one on the PCB of the PA module.
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