Experimental UV380 Plus 10W and 5W radios calibration changes version

[VK3KYY]

I have created another experimental version with changes to the calibration system to support the 10W UV380/390 Plus radios

This version also includes versions for the normal 5W UV380/390 , DM-1701 and RT-84, as it includes changes to the DM-1701 to adjust for the top of the LCD display being blocked by the plastic case of the radio

https://opengd77.com/downloads/MDUV380_ ... dee2485ce4

Important changes in this version

1. Baofeng DM-1701 and Retevis RT-84 are now different firmwares. The only difference is the changes necessary for the screen height changes
2. Some translations have been updated
3. Bug fix display of CTCSS during Tx under some conditions
4. Internal bug fixes
5. Change power steps for the 10W radio versions
6. Changes to handling of 5W / 10W power setting from the calibration data


Important

Using this version without using the Calibration menu - > Factory Reset will cause the output power on the 5W,4W,3W settings to be lower than in previous versions

10W radio users should immediatly use Options -> Calibration -> Factory Reset -> (SK2 + Green) to re-read the official data, becasue I have modified the functionality when the factory data is read, so that it applies an approximate coffection factor so that the 1W setting is 1W , instead of 2.5W, and the 5W and 10W settings are roughly correct.

I have been working with VK5DET who has a 10W UV380 and also has multiple power meters, to determine the correction factors necessary to compensate for the apparently incorrect factory calibration data in this radio. However, becuase this is only 1 data point, the correction factors will not be accurate on all radios, and its probable that it won't be possible to accurately compensate the power output on these radios, and operators will need to calibrate the power of their own radios.

The data from VK5DET shows that his radio is only capable of producing 10W on 2m and the upper end of 70cm, (450MHz). On the lower part of 70cm his radio only produced 8.5W. Also on 135,155 -> 175 MHz his radio also would not produce 10W

Now to get very technical

The factory calibration has 4 data points per frequency band.
The frequency bands / ranges are now 10MHz, and on VHF are 135MHz -> 175MHz and on UHF are 400MHz -> 490MHz

I made a small change to the band edges on VHF becuase they were 9.5MHz wide in the official data, and 500kHz made virually no difference to the power output, so I have changed this to 10MHz ranges

We don't know the actual names of the 4 data points, but they appear to be rounghly

1. UNUSED / 0
2. Low power setting in the official firmware. Approx 1W
3. Mid power setting in the official firmware. Approx 2W -> 2.5W
4. High power setting in the official firmware. Approx 4W -> 4.5W

Testing all my radios, on multiple frequencies, I found that none of the official data was accurate. With maximum error mostly being on the High power / 5W setting, where power ouput was often 4.5W instead of 5W

Also. The DM-1701 outputs significantly less power than the UV380. My DM-1701 will only produce 5W on 2m, it would only produce 4.5W or less on 70cm.

The UV380 will output 5W over nearly the entire operational range, from 135 - > 175MHz and 400MHz -> 480MHz
On 2m my UV380 will produce over 8W, however I do not recommend that people try using their UV380 at very high PA drive levels, becuase this will be beyond the operational limits of the PA FET and may cause damage, as well as possibly increasing spurious emissions


In previous versions of the calibration functionality, the calibration power levels were 1W,2W and 4W, however this required a multiplier coefficient to produce 5W, so I have changed the calibration functionality so that the target power levels are 1W,2W and 5W.

After a radio is calibrated by the operator, this will result in more accurate 5W output


You may have noticed in my list of data points, that data point 1 is not used by the official firmware, however we use it for the 250mW setting, and in order that there is data in this data point, the firmware has always calculated a value for this, based on the "Low" / 1W setting.
This has not changed in this latest version, except the value is now a coefficient rather than a level offset. i.e a multipler rather than a subtraction of the PA drive number.

To get even more technical....

The "Adjust" value in the calibration screen is the PA drive level. This value is multiplied by 16 in the firmware and set to the Digital to Analogue Converter in the radio which generates the analogue PA drive voltage.

Hence changing the Adjust, changes the PA drive voltage and hence changes the PA power level.

It should be noted that

(a) The output power is not linear to the PA drive voltage, and the PA FET decreases in effeciency with frequency, so higher PA drive "Adjust"
values are needed or higher frequencies.
Also. The PA output filters are are slightly like band pass filters, with a optimum gain point, which is generally in the mid point of the VHF and UHF overall frequency range. Hence the 10W UV380 can only produce 10W at approximately 450Mhz
(b) Output power varies depending on battery voltage, so all calibration should ideally be perfromed with the battery at 100%.
(c) The PA FET saturates at high PA drive settings, hence if increasing the PA drive "Adjust" value is not causing an increase in output power, then you should not keep increasing the Adjust value. The Adjust value should only be increased until it stops making the output power increase
(4) There is also a lower cutoff point, below which the PA drive voltage is too low and the PA FET stops working entirely. This occurs when setting the 250mW setting
(5) Unfortately becuase the factory power calibration / Adjust value is only stored as 1 byte, it can only have values of 0 -> 255 and this results in quite granular steps at low power levels, e.g. 250mW



And finally.

If anyone has a power meter and has time to conduct some calibration tests, please post here and I will start another thread to discuss this, so that we can improve the power level accuracy for everyone using UV380, DM1701 or UV380 10W

[m1dyp]

thanks

[VK3KYY]

This has now been superseded by Alpha 2.2