10W UV380/UV390 PLUS - WORK IN PROGRESS

[KK7QLA]

I don't have a power meter but I can probably figure something out.

I did notice that RX_UHF_LNA ,PA2 and RX_VHF_LNA, PA5 both did seem to control the LNAs, if thats anything.

From what I can tell its only the 10w thats effected by this.

[VK3KYY]

I Think I found it.
PA_BAND_SEL PC6

PC6 O > Output C6 = Low
PC6 T > Toggle pin C6 = High
PC6 T > Toggle pin C6 = Low
PC6 I > Input C6 = Low
backlight change and toggle
-----------------------------------------------------------------


In DMR
PC4 O > Output C4 = Low
PC4 T > Toggle pin C4 = High
PC4 T > Toggle pin C4 = High
PC4 I > Input C4 = Low
no change in backlight

In DMR
PC5 O > Output C5 = Low
PC5 T > Toggle pin C5 = High
PC5 T > Toggle pin C5 = High
PC5 I > Input C5 = Low
no change in backlight

In DMR
PC6 O > Output C6 = Low
PC6 T > Toggle pin C6 = High
PC6 T > Toggle pin C6 = Low
PC6 I > Input C6 = Low
backlight change and toggle

I've sent you an emial with a special version and loads of instructions;-)

[VK3KYY]

I don't have a power meter but I can probably figure something out.

OK. Without a power meter its going to be a bit tricky.

If even transmitting into a dummy load, any other radio in the shack will probably get the signal as S9+60

But possibly you can kinda measure the power by using another Rx

[VK3KYY]

With information from KK7QLA we I now know that the LCD backlight control signal is on MCU / CPU pin PC6, this pin is used as the PA band select control in the original UV380

At the moment I don't know what pin now controls the PA band select, but assuming that the LCD backlight and the PA band select pins have been swapped,

I have build a version where the PA band select now uses pin PD8, which is my current best guess about what pins are controlling the PA band select


See

downloads/MDUV380_DM1701/Firmware/Exper ... 0_PLUS.bin

Note.
The file is .bin and not .zip, hence you need to select "Legacy firmware files (*.bin)" in the firmware loader to load this file.


I'm almost certain this fixes the backlight problem, but somone needs to check the power levels when transmitting on FM on VHF and UHF, because even if the backlight and PA band select pins have only been swapped, there is a possibility that the polarity of the signal to select VHF vs UHF may have changed.

If the power looks correct on both bands, then PA Band select is definitely on PD8.

If the power is only correct on one band, or is wrong on both bands, then its likely that PD8 is not being used for the PA band select

It should also be noted that if you load this firmware into a 10W radio, the output power should be approximately 2 x the value displayed on the screen, i.e 5W should output approximately 10W

For anyone with a 5W PLUS version which seems to have the backlight etc problems, the the power is probably going to be as displayed on the screen...

Edit

I just did some tests on my RT-3S aka MD-UV380, and reversed the polarity of the PA Band control signal, so that the VHF PA was selected for VHF and the UHF PA was selected for VHF, and the results are somewhat interesting

If the band select is inverted, then VHF Tx seems to work OK and produces more power (5.5W) than when the band select is configured correctly
However no power was produced on UHF.

This seems to indicate that the tuned circuits in both PA's operate as a Low Pass Filter.

ie. on VHF the UHF PA LPF was enabled, and the reason that more power was observed is that the thrid harmonic of the VHF frequency, ( 145Mhz x 3) = 435Mhz is being mesaured as well as the main signal on 145Mhz, hence the power output was 40% higher than it should be.
This could be confirmed by using a SDR or a Tiny SA, but I've not had time to do that today

On UHF, the radio hardware would enable the VHF PA, which would greatly attenuate the 435Mhz Tx signal. Which doing a rough calculation would need at least 30dB attenuation to reduce 5W to < 0.05W that my power meter can measure.


So. If the UV380 PLUS version, I linked in this post works on UHF and also VHF with consistent power levels on both bands then, the PA band select pin has been guessed correctly and the polarity is the same as in the RT-3S / normal UV380.

If however there is little or no power on UHF then by guess is wrong.

[R2BLT]

Thank you so much! It works !!!

[VK3KYY]

Thank you so much! It works !!!

Please measure the power on VHF and UHF if you have a power meter and confirm it seems OK on both bands

If you have any form of spectrum analyser e.g. Tiny SA or even a SDR, please check the spectural purity of the transmitted signal, because I am not sure the PA band select control is correct.

[R2BLT]

I can measure the power a little inaccurately, I have a Surecom sw-102)

[VK3KYY]

I can measure the power a little inaccurately, I have a Surecom sw-102)

Inaccurate is OK.

I use a similar SWR / Power meter for my tests

I only need to know whether it is transmitting good power on both VHF and UHF

Do you have a SDR dongle.

I also need you to transmit on 145MHz and check the signal level at 435MHz (3 x harmonic).

3rd harmonic should be at least 30dB lower than signal on 145MHz

[R2BLT]

Hi, harmonic measurements using SDR. The power of 50 mW , if you make a large power SDR is overloaded at the input.
The results are here https://drive.google.com/file/d/1ZPY-hv ... sp=sharing

[VK3KYY]

Hi, harmonic measurements using SDR. The power of 50 mW , if you make a large power SDR is overloaded at the input.
The results are here https://drive.google.com/file/d/1ZPY-hv ... sp=sharing

Thanks. I've scaled the images to make the file size small enough for the forum data limits

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So it looks like power is similar on both VHF and UHF, which is good

Possibly someone else has a spectrum analyser they can use to confirm the strength of the 3rd harmonic, becasue it looks like even on 50mW the signal level is too strong to be correctly measured by the SDR

Can you try 5W setting on the radio on both VHF and UHF and confirm what power is produced, because the 5W setting in OpenGD77 uses the "High" power calibration setting from the manufacturer data