RT-900 Quick Calibration to Another Radio
Added 2025-07-25 21:45:34 +0000 UTCFor Thiago A.G.
Comments
Frequencies are derived from a 26 MHz oscillator. It's this oscillator being out that causes off frequency issues. But the correction is global, if you are correct on 70cm you will be correct on 2m. If you are having APRS issues I might suggest adjusting the filter which is available in the newest release.
Marcus Dudley
2025-10-28 02:43:58 +0000 UTCI calibrated my RT-880G weeks ago against a Baofeng and got an XTAL of 90. However, today I tested the beta 6 firmware against a Yaesu transceiver, which I assume is more accurate, and I got -239. When I did the calibration again with XTAL set to -239, I got a new XTAL of 0, so I assume that means my calibration is good. However, I've never been able to get it to receive APRS and it rarely can send APRS successfully. I tried the calibration again using 144.395 mhz (to be near to, but avoid conflicting with APRS), and I got an XTAL of +604. Using that calibration, I was finally able to receive a few APRS beacons from the local repeater successfully (but not all...maybe the others are incompatible formats?). I also was able to send about 1 in 10 APRS beacons successfully. So, it seems like I need different calibrations for 2M and 70CM. Is that possible? I suppose the other possibility is my old Yaesu FT-100D is off frequency differently in both bands. For reference my test results were: Test freq: 449.000 Min: 448.997700 Max: 448.999300 Midpoint: 448.998500 Difference: -149.999 XTAL671: -224 Test freq: 144.395 Min: 144.395400 Max: 144.397200 Midpoint: 144.396300 Difference: 129.999999998631 XTAL671: 604
Eric Black
2025-10-27 20:42:42 +0000 UTCExcellent video Marcus!
Matt P
2025-07-27 17:55:19 +0000 UTCFollowed your video and got -647 for Xtal previously I had -643 so I was close lol
Norm Max
2025-07-27 13:40:29 +0000 UTC
