OpenGD77

https://es.aliexpress.com/item/1005001459230530.html


Does anyone know where to find what chip is installed on this radio?

AFAIK, this radio is just a relabeled Kydera CDR-300UV.
The manufacturer claims it's a dual-conversion superhet, so an RF part is clearly different from GD77/dm1801.
Can't say a thing about DMR chip. There are no PCB photos available, or at least I couldn't find them.

Yes, maybe a same radio....

Well, if is a superhet radio, is not a good radio to port opengd. No images to see internally.

EB3AM wrote: ↑

Thu Oct 01, 2020 3:12 pm

Yes, maybe a same radio....

Well, if is a superhet radio, is not a good radio to port opengd. No images to see internally.

Why do you say that? Please explain.

YT5HOK wrote: ↑

Fri Oct 02, 2020 7:08 am

EB3AM wrote: ↑

Thu Oct 01, 2020 3:12 pm

Yes, maybe a same radio....

Well, if is a superhet radio, is not a good radio to port opengd. No images to see internally.

Why do you say that? Please explain.

Probably because the GD77/DM1801/RD5R use the AT1846S transceiver chip which is not superhet, its some sort of direct conversion SDR inside the chip, but the Rx chip in the MD380 is some sort of superhet (I don't know the part number of that chip)

VK3KYY wrote: ↑

Fri Oct 02, 2020 10:25 am

Probably because the GD77/DM1801/RD5R use the AT1846S transceiver chip which is not superhet, its some sort of direct conversion SDR inside the chip, but the Rx chip in the MD380 is some sort of superhet (I don't know the part number of that chip)

Hi Roger,

Yeah, I'm aware of technical specs of radios you mentioned, I have GD-77, MD-380, MD-390G (and MD-9600), while I sold RD-5R. There is experimental firmware for superhet radios, as we all know, and also I see that guys are working on porting OpenGD77 (OpenDMR, OpenRTX, or whatever anyone calls it) to MD-380 (OpenRTX), so that's why I asked. Nothing really important, just wanted to know his reasoning, I might be unaware of.

Yes. I know there is a port to the MD380 but I have not checked on the progress of that project recently

Well, finally I got a grab on my CDR-300UV. As a test, I've successfully programmed it via RT73 CPS - so most likely it's really the same radio.
I've opened it to investigate. It's really a superhet, though I found only 1st IF filters - but it's HR_C7000-based, so I doubt it will be possible to port OpenGD77 to this radio in the nearest future.

Yesterday I received an RT73. It's a well-built, compact radio that seems to work relatively well. I have a uhf DMR repeater about 80km from home that reaches me very marginally. With the GD77 it is impossible to hear it with the base antenna, although if I receive it in very specific places on the farm.
Well, the Rt73 receives it perfectly with the base antenna. It’s not a great comparison, but it’s the only one I have.
Now ... the firmware is a disaster. the CPS is no wonder either.
In VFO mode if you put a repeater and adjust the frequencies of TX and RX, with its offset, this offset is lost when moving the dial. Absurd.
In channel mode, it is like almost all DMRs, designed for a professional environment.
We hope someone makes an "openRT73" and with it being 10% of the OpenGD77 I feel happy!

Thank you openGD77 team for getting us to forget how bad the DMR TRANSCEIVER firmware is.

Attached are some photos of the little I could see from inside the rt73.

Just curious, how did you get the rt73 apart? I have one and it is having issues with staying powered on. Retevis is not wanting to play very well right now. I refuse to pay $100 to ship the radio back to them to get my $150 back I paid for it. I want to check a few of the solder joints in it, but haven't seen a good way to take it apart yet.