Loud 'click' after speaker is turned off // Recommended power supply?

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EA5JAQ
Posts: 86
Joined: Thu Jul 16, 2020 6:08 am

Loud 'click' after speaker is turned off // Recommended power supply?

Post by EA5JAQ » Mon Jan 09, 2023 4:43 pm

Hi all!

A couple weeks ago I received my V5 MD-9600 and I've been testing the firmware, the radio gets excepcionally better with the open firmware.

However, each time a 'beep' is played, or after receiving a signal (aka, each time the speaker is turned off), you can hear a loud 'click', especially at low volumes (as I'm using it at home, always, because even the lowest volume is pretty high). I'm convinced this is a hardware issue due to bad design, but is there any way to solve it, even if a hardware modification is needed? A solution I can think of could be adding a relay that switches off the speaker just before the speaker amp is turned off, but that would come with its own issues (I'd need to find an available GPIO pin, modify the source which is not yet published, and also you'd still hear the relay 'click', so that wouldn't be much of a solution :( ). I don't know if there's any way to solve this in the firmware or with any other slight hardware modification.

Another doubt I had is if anyone knows how much current does the radio need to transmit at full power. So far I've been using an old 1.5A power supply I had at home and obviously you can't get much Tx power with it, but it served its purpose just for trying out the firmware and playing around with it. If anyone can recommend a simple power supply (not a fancy big bench supply, just a reliable one that does the job), I'd really appreciate it. I'm planning on buying a Xiegu G90 in the near future (I think I'm starting to have way too many radios :lol: ) and that one needs 8A, so anything that could work for both would be great.

Anyway, thanks for the effort porting the fw to the MD-9600 and MD-UV3x0. I hope there are plans in the near future to release the source code now that it's starting to look really stable (couldn't find any bugs myself), I'd love to check it out and learn from it, as I did with the DM-1801 code.

73

G4EML
Posts: 919
Joined: Sat Nov 16, 2019 10:01 am

Re: Loud 'click' after speaker is turned off // Recommended power supply?

Post by G4EML » Mon Jan 09, 2023 5:10 pm

The loud click was a problem on the early versions of the 9600. Then the factory fixed it for a while, and then re-introduced it on the latest version!

I developed a mod to fix this on the early radios and it appears to still work on the latest ones. Do a Google search for G4EML MD9600 Mods and you should find it. The problem is the mute circuit applies a short circuit to the amplifier input. This messes up the DC bias and causes the click.

Roger has also included a firmware click reduction mode which can help. You should find that in Options/Sound Options/Click Suppr.
This option generates a PWM ramp on the mute signal which slows the rise time.


Regarding power supply. The radio will consume up to 10A on full power transmit. Typically around 8A. You need a 13.8V supply if you want to get the full output power. Most Ham dealers should have something suitable.

Colin G4EML

EA5JAQ
Posts: 86
Joined: Thu Jul 16, 2020 6:08 am

Re: Loud 'click' after speaker is turned off // Recommended power supply?

Post by EA5JAQ » Mon Jan 09, 2023 5:55 pm

G4EML wrote:
Mon Jan 09, 2023 5:10 pm
The loud click was a problem on the early versions of the 9600. Then the factory fixed it for a while, and then re-introduced it on the latest version!
If only these chinese brands did a bit of testing before mass producing these radios... But at least this problem can be solved (unlike the MD-UV390 gps's poor performance, etc.).
G4EML wrote:
Mon Jan 09, 2023 5:10 pm
I developed a mod to fix this on the early radios and it appears to still work on the latest ones. Do a Google search for G4EML MD9600 Mods and you should find it. The problem is the mute circuit applies a short circuit to the amplifier input. This messes up the DC bias and causes the click.

Roger has also included a firmware click reduction mode which can help. You should find that in Options/Sound Options/Click Suppr.
This option generates a PWM ramp on the mute signal which slows the rise time.
Thank you so much, I just did a quick search and it looks feasible, although extremely difficult, there's not much space there :? Might be worth a try though (I'll buy a couple LA4425As off Aliexpress before I do anything, in case I break it :lol:). Roger's fix did the trick too, it's impressive.

BTW I also found your mods to turn the screen orange and green, and it looks really cool, I'm definitely trying those. :lol:

SP2GPU
Posts: 6
Joined: Mon Mar 28, 2022 6:43 pm
Location: Kosakowo

Re: Loud 'click' after speaker is turned off // Recommended power supply?

Post by SP2GPU » Sun Jan 29, 2023 6:39 pm

Hello.
I used 2.2uF. No clicking and very nice audio.
I recommend.

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