I calibrated the 220 MHz ham band using the Baofeng UV-S9X3 I just got. It's supposed to Xmit on two power levels on each band (2m, 1.25 m, 70 cm), L & H. The funny thing is, it only transmits on one power level on the 220 MHz band. Yet the display toggles the power indicator just like the other two bands. It Xmits 3.2 W - period - on 220. So 3.2 W is the data point I used, but since the response of the AD8307 is linear over the region I'm using, it should be fine. Since I have no other means to go to a higher power on 220, I'll have to settle for that for now. But for what I've seen on the other bands, it should be reasonably accurate for higher powers on 220.
The final two ham bands I needed to calibrate are 2 m & 70 cm. After that, if there are no glaring problems, I can move forward with the next steps. These are the results of the final two band calibrations in units of Watts.
Transceiver Yaesu FTM-7250D
VHF 146.000 MHz
Radio PWR Set | hp 437B | Project | Error |
5 | 5.0 | 4.8 | -0.2 |
25 | 24.1 | 24.4 | +0.3 |
50 | 45.4 | 45.8 | +0.4 |
UHF 445.000 MHz
Radio PWR Set | hp 437B | Project | Error |
5 | 4.1 | 3.5 | -0.6 |
25 | 22.8 | 21.7 | -1.1 |
50 | 45.7 | 45.9 | +0.2 |
The highest dB error is UHF low power: 4.1 W (hp) vs 3.5 W (Project). That's 0.7 dB, which is reasonable and acceptable for this system. I've calibrated the development system now and I'm satisfied it's worth moving forward. When it finally goes into a nice enclosure (a whole other project) and the breadboarding is gone, I'll recalibrate all the bands.
Next I want to pull the tiny OLED display and use a larger 2.42 inch 128x64 type similar to what I've used on a previous project meter shown in the pic. I think the last unused one I bought is yellow. When I get that going, I have another upgrade for this project in mind ...