OpenGD77

Hello,

I have GD-77 and DM-1801 transceivers.
The GD-77 modulation is much louder.

For FM with the DM-1801 this can be compensated by raising the analog mic gain
in the calibration window of the CPS. But on DMR the modulation is not getting louder.

Is there a way to achieve a louder DMR modulation with the built in microphone?
Would it be possible to allow a DMR mic gain of more than 12 dB in the firmware?
I think there is no calibration value that affects the DMR mic level. Is that correct?

Can this maybe only be cured with a hardware modification of the mic amplifier?

73 es tnx,

Daniel

Hi,

in the radio
menu
sound settings
DMR microphone in dB
under
Fm microphone numbers (I don't know what the difference is or why)

But maybe you write this too. (?)
I hope I write well and help.

Greeting

Hello,

thank you for the reply.

Yes I know the DMR microphone gain setting. But this is not enough.
If I set this to the maximum value the modulation is still not very loud.
This seems to be a general problem with the DM-1801.
For FM I could fix it using the calibration values.
But I could not find a setting that helps for DMR.

So the question is how the DMR modulation can be boosted even more.

73,

Daniel

Hi,

DL2NEQ wrote: ↑

Sat Jul 17, 2021 7:06 pm

Hello,

thank you for the reply.

Yes I know the DMR microphone gain setting. But this is not enough.
If I set this to the maximum value the modulation is still not very loud.
This seems to be a general problem with the DM-1801.
For FM I could fix it using the calibration values.
But I could not find a setting that helps for DMR.

So the question is how the DMR modulation can be boosted even more.

73,

Daniel

Maybe it's just a mechanical problem (too small hole, too much foam, etc) ?


Cheers.
---
Daniel

As far as we know there is no way to increase the microphone gain any more than is currently available. The only remaining option would be a hardware modification.

Colin.

It should not be a mechanical problem.

I even tried different electret microphones with some wires and open transceiver housing.
So the GD77 seems to be the better overall radio. Although I like the additional buttons of the DM-1801.

But performance on DMR seems to be limited then...unless somebody has an idea what needs to be changed hardware-wise.
There seem to be no schematics available for the DM-1801 (at least I couldn't find them yet).

73,

Daniel

For what it's worth I have a DM-1801 with the original firmware
V2.00.09. My mic audio has been reported back to me as loud.
I have had to add a small piece of tape over the mic hole then with
a pin make a small hole. This reduced my audio.

A friend who purchased a DM-1801 about a year after me has
a newer firmware and his mic audio is quite a bit lower.

Don't know if V2.00.09 is available ?
I also don't know what the difference might be between
the newer firmware and V2.00.9 but with
my version I do have to create a RX Group list or have no receive.

Ken

Na última configuração do Open GD 77 tem a possibilidade de programar o ganho de microfone que fica ajustado para 0 Dbm. Basta aumentar para +5 Dbm que resolve.

In the last configuration of Open GD 77 you have the possibility to program the microphone gain which is set to 0 Dbm. Just increase it to +5 Dbm that resolves

DL2NEQ wrote: ↑

Sat Jul 17, 2021 11:52 pm

It should not be a mechanical problem.

I even tried different electret microphones with some wires and open transceiver housing.
So the GD77 seems to be the better overall radio. Although I like the additional buttons of the DM-1801.

But performance on DMR seems to be limited then...unless somebody has an idea what needs to be changed hardware-wise.
There seem to be no schematics available for the DM-1801 (at least I couldn't find them yet).

73,

Daniel

All of the Baofengs I have or ever had (BF-T1, UV-5r, RD-5r, DM-1801 and DM-X) were suffering from the same problem of insufficient mic gain.

The solution is to replace a mic load resistor (the one between mic+ and power supply), this will increase a mic internal amplifier gain (more resistance means more gain to some extent). Original resistor values are from 0.82k to 1.2k depending on radio model, which IMO is very low. From my experience the optimal value is about 3.3k to 6.8k.

For dm1801 I've attached a (poor quality) photo, you need to replace the smd0402 resistor outlined in red. Much more common smd0603 just barely fits there.

I modded my dm1801 with 4k7 smd0603 resistor salvaged from an old PC motherboard, now DMR mic of -6dB (yep, that's minus 6dB) and FM mic of about 3 are just fine.

This is exactly what I need.
Thank you very much!

73,
Daniel