I have found a bug in the power calculation for VHF which would account for some of the strange results.
The correction should be in the next release from Roger.
This should then make the 40W 25W 10W and 5W settings the same (or very similar) to the official firmware.
Powers below 5W are not going to be correct, they are calculated from the calibrated power setting for 5W but the slope of the curve is very steep at low powers and even a small error results in a large power variation. I have adjusted the figures to match my radio but on looking at the figures from ON6XX the slope is different. I suspect each radio will be unique in this area.
The PA stages were never designed to run at such low powers so it may never be possible to get accurate low powers without calibrating each radio.
Colin G4EML
Calibration of the transmitter power in the 2M band
Re: Calibration of the transmitter power in the 2M band
Calibration files are unique to each radio, so comparing yours with another will not be of much help.
There are lots of variables here. A measurement of 20W UHF and 30W VHF is quite possible and doesn’t necessarily indicate a problem with the radio.
Are you testing on FM ? Most power meters will not read correctly on DMR.
Are you using a 13.8V power supply? Running below this voltage or using long power cables will reduce the power output.
Is the power meter connected directly to the radio with a very short good quality cable or preferably with no cable at all ? Even a short length of thin cable will reduce the power measured, especially on UHF.
Even if the power reading is accurate I wouldn’t be too concerned about it. The radio is still within a few dBs of its rated power and such a small reduction will hardly be noticed in normal use. Range is square law related to power, so even at half power you would still have 70% of the range.
Colin G4EML
There are lots of variables here. A measurement of 20W UHF and 30W VHF is quite possible and doesn’t necessarily indicate a problem with the radio.
Are you testing on FM ? Most power meters will not read correctly on DMR.
Are you using a 13.8V power supply? Running below this voltage or using long power cables will reduce the power output.
Is the power meter connected directly to the radio with a very short good quality cable or preferably with no cable at all ? Even a short length of thin cable will reduce the power measured, especially on UHF.
Even if the power reading is accurate I wouldn’t be too concerned about it. The radio is still within a few dBs of its rated power and such a small reduction will hardly be noticed in normal use. Range is square law related to power, so even at half power you would still have 70% of the range.
Colin G4EML
Re: Calibration of the transmitter power in the 2M band
Loading firmware does not change the calibration. That is stored somewhere safe so it can’t be changed accidentally.
There is no factory default setting, every radio is different. If someone has changed something then there is no way back unless they saved the settings to their computer before they started.
If you post your calibration file here I will
have a look at it and see if there is anything obviously wrong. The calibration screen is accessed by Control T in the official CPS. Then you can read the radio and save the file to your computer.
The performance and range on digital should be similar to that on analogue. Of it is not then there might be something faulty in your radio.
Also try both VHF and UHF, only one may be faulty.
Colin.
There is no factory default setting, every radio is different. If someone has changed something then there is no way back unless they saved the settings to their computer before they started.
If you post your calibration file here I will
have a look at it and see if there is anything obviously wrong. The calibration screen is accessed by Control T in the official CPS. Then you can read the radio and save the file to your computer.
The performance and range on digital should be similar to that on analogue. Of it is not then there might be something faulty in your radio.
Also try both VHF and UHF, only one may be faulty.
Colin.
Re: Calibration of the transmitter power in the 2M band
Those files are the codeplugs and not the calibration files.
Calibration files have the suffix .test and are saved from the official CPS using the hidden test menu. (Control + T )
Colin.
Calibration files have the suffix .test and are saved from the official CPS using the hidden test menu. (Control + T )
Colin.
Re: Calibration of the transmitter power in the 2M band
What power level should we stay at or above to avoid trouble in DMR? I have V.2 hardware. I’ve been running my radio at 250 mw for UHF DMR with a Pi-Star hotspot. So far, no apparent issues or bad signal reports.
For local repeaters, FM or DMR, I run 5, 10 or 25 watts. All to a ground plane antenna on the roof. Running plain FM, power output on a Maldol MR-2000 meter and dummy load always measures a little lower than the radio power setting says. The biggest discrepancy is at the 40w setting, where I measure 30w on 2m and 22w on 70cm. Of course, I have no idea how accurate the meter is.
My signal gets where I need it to go, which is all that really matters.
For local repeaters, FM or DMR, I run 5, 10 or 25 watts. All to a ground plane antenna on the roof. Running plain FM, power output on a Maldol MR-2000 meter and dummy load always measures a little lower than the radio power setting says. The biggest discrepancy is at the 40w setting, where I measure 30w on 2m and 22w on 70cm. Of course, I have no idea how accurate the meter is.
My signal gets where I need it to go, which is all that really matters.
Re: Calibration of the transmitter power in the 2M band
If your radio works at 250mW then its not one of the radios that has a problem with the PA response time.KD7MW wrote: ↑Fri Jun 17, 2022 4:44 amWhat power level should we stay at or above to avoid trouble in DMR? I have V.2 hardware. I’ve been running my radio at 250 mw for UHF DMR with a Pi-Star hotspot. So far, no apparent issues or bad signal reports.
For local repeaters, FM or DMR, I run 5, 10 or 25 watts. All to a ground plane antenna on the roof. Running plain FM, power output on a Maldol MR-2000 meter and dummy load always measures a little lower than the radio power setting says. The biggest discrepancy is at the 40w setting, where I measure 30w on 2m and 22w on 70cm. Of course, I have no idea how accurate the meter is.
My signal gets where I need it to go, which is all that really matters.
Anecdotally, people have told me the openmd9600 works on lower power settings when the official firmware won't.
Re: Calibration of the transmitter power in the 2M band
VK3KYY wrote:
> If your radio works at 250mW then its not one of the radios that has a problem with the PA response time.
> Anecdotally, people have told me the openmd9600 works on lower power settings when the official firmware won't.
Good to know. Thanks, Roger!
> If your radio works at 250mW then its not one of the radios that has a problem with the PA response time.
> Anecdotally, people have told me the openmd9600 works on lower power settings when the official firmware won't.
Good to know. Thanks, Roger!
Re: Calibration of the transmitter power in the 2M band
The calibration file looks normal.