OpenGD77

I finally received the RT3S, (which is just rebranded TYT MD-UV380) , and as usual one of the first things I to is take it apart


youtu.be/ScoVslqV5eY


What find interesting, and a bit disappointing is the RF section this radio, does not look half as good as in the GD-77.

It does not have completely separate PA stages for VHF and UHF. It only has 1 PA FET, followed by what is probably a complex band pass filter, for UHF and another filter for VHF.

This design is similar to whats in the RD-5R, and results in much worse Tx RF spectral purity.

Also strangely the baseband chip is in a different shielded area to the RF / PA section, but the DMR chip seems to be in the same shielded section as the RF / PA.

The GD-77 design seems to be much more sensible, the RF baseband chip, being in the same shielded area as the RF / PA section


Also. I can't see a EEPROM in this radio, so I presume all settings are saved to the 16Mb flash memory.

congratulations on your new purchase ... I am very anxious to see your progress in modifying this radio ... I am in possession of the monoband uhf version and I can assure you that it works very well ....
ciao Roger

The mono band version is a lot different.

There is some work progressing for this, but not by me.

See

https://github.com/n1zzo/OpenDMR

VK3KYY wrote: ↑

Sun Jul 05, 2020 11:23 am

The mono band version is a lot different.

There is some work progressing for this, but not by me.

See

https://github.com/n1zzo/OpenDMR

ok Roger

This radio was a lot more expensive than the GD77 and it seems the quality of RF performance is lower. This radio was sold around $130 whereas i got my GD77 for $70. That`s like two times cheaper than the RT3S. The only advantage was the big screen and more memory.

The price of the RT3S in Australia is slightly lower than the GD-77.

However the price of exactly the same radio, when branded as TYT is much more expensive.

I don’t know how Retevis could make any profit from selling these radios at below the wholesale price of the TYT MD-UV380.
Retevus may actually be part if TYT or TYT’s parent company, rather than a separate company who needs to make max profit to survive

The RT3S is very popular in Australia because of its low price and its large memory capacity, and pretty screen, but it looks like it’s actually an inferior radio to the GD-77, and TYT have simply done a hack on the MD-380 PCB and fitted the AT1846S tri-band RF chip from the GD-77 and squeezed in another RF section, without making a new chassis.

Having the pretty screen is probably not really a benefit , because the colour LCD screens are known to generate RF QRM when they are being updated, and they also require a backlight to be visible,

Hello,

was there any progress, as i'm experiencing, that uv390/uv380 both has much worser rf than baofeng 1801. The difference is significant. Do you think (i'm notified, that i can destroy station) if i change values in eeprom, I would squeeze out some more of it?
http://rctnotes.blogspot.com/2016/02/re ... d-380.html - but in this case i need to restore to factory fw first, and than back to opengd77. Is it possible to add feature directly to opengd77 cps, like it's possible for baofeng or gd77 to put it through the tests?

thank you

What exactly do you think is different about the performance? What measurements have you made?

There is very little that can be adjusted on the MDUV380. It is unlikely that anything you change would make any difference.

Colin G4EML

Hello,

if you put uv380 vs baofeng 1801 together, original antennas and enviorment, baofeong will recept weaker signals vs. uv380/390 will barely get or will be even deaf. I was thinking that reception of the 380/390 is much worser than baofeng's one, even it's cheaper than TYT station. I think the OP has asked the same question.

It's probably an hardware issue, but I would still like to check the parameters (rx sensitivity parametres), because i suspect it has worser RX reception especially on 2m band.

S58SMS wrote: ↑

Tue Dec 27, 2022 7:16 pm

Hello,

if you put uv380 vs baofeng 1801 together, original antennas and enviorment, baofeong will recept weaker signals vs. uv380/390 will barely get or will be even deaf. I was thinking that reception of the 380/390 is much worser than baofeng's one, even it's cheaper than TYT station. I think the OP has asked the same question.

It's probably an hardware issue, but I would still like to check the parameters (rx sensitivity parametres), because i suspect it has worser RX reception especially on 2m band.

The RF hardware on the 1801 and UV380 are completely different, so the RF performance will be different