OpenGD77

rafaelarcillo wrote: ↑

Fri Sep 04, 2020 10:09 pm

Hello all...

I´m using DM-5R with OpenRD5R Built 07:25:41 Aug 29 2020 and my radio keeps the display always on. Has anyone here noticed this same problem?

Thanks
PY2GPS
Rafael

https://github.com/rogerclarkmelbourne/ ... md#timeout

Thanks Roger!

Today uploaded R2020.10.01 sgl https://github.com/rogerclarkmelbourne/ ... ses/latest
with R2020.10.07 cpsinstaller https://github.com/rogerclarkmelbourne/ ... ses/latest
Working great !!! Even the flashlight (Sq2 + 5) and a great customisable/limited scan-range !

Roger suspects that the bad performance of the RD-5R is related to hardware voltage instabilities. This seems to be the case. I have, as I wrote before, three RD-5R. One is performing very good with the OpenGD77 firmware. One is performing not so good (minimum BER 1.8%) and one is performing extremely bad (BER 13.7%). This very bad unit has another problem: If I increase audio volume to being pretty loud the unit reboots. The other two units do not show this problems.

So it is unlikely that the bad performance of many RD-5R with OpenGD77 firmware can be fixed with changes to the firmware.

Unfortunately, I never tested how the performance of the bad units was with the original firmware.

I just managed to repair one of my bad RD-5R. It went from BER 13.7% to BER 0.3% and no more reboots with high audio volume. The radio had bad solder connections on the power transistor module (marked as H0606E JC1728, middle pin) and on the audio amplifier chip (marked as TDA2822, Pin 8 ground). I just resoldered these connections.

DL1DBY wrote: ↑

Mon Nov 09, 2020 4:40 pm

I just managed to repair one of my bad RD-5R. It went from BER 13.7% to BER 0.3% and no more reboots with high audio volume. The radio had bad solder connections on the power transistor module (marked as H0606E JC1728, middle pin) and on the audio amplifier chip (marked as TDA2822, Pin 8 ground). I just resoldered these connections.

That's interesting to know.

Thanks for posting.

da3020 wrote: ↑

Mon Nov 09, 2020 11:23 pm

I can't decide what to buy. I have an experience with OpenGD dm-1801 and I like it but it looks too big for me. I often wear station on my shirt pocket an 5R is much smaller but I care about usability and functionalyty. Is it mostly the same OpenGD for those two stations? (soldering of transistors doesn't scare me). Give advice, please!

Having bought 3 units of the RD-5R will only one working as it should I would strongly advise against buying an RD-5R. Even though it is small and cheap and nice with the OpenGD77 firmware.

da3020 wrote: ↑

Tue Nov 10, 2020 7:57 am

ve7mdt wrote: ↑

Tue Nov 10, 2020 7:12 am

... RD-5R is a viable option for you

Thanks alot.


Also, DL1DBY, how did You measure BER? Are any improvised ways?

I am using a MMDVM duplex hotspot with Pi-Star which shows the BER. Big repeaters seem to have automatic adjustments for radios that are slightly off-frequency. The MMDVM does not do any adjustments of this kind which is not so good generally but useful in this case.

VK3KYY wrote: ↑

Mon Nov 09, 2020 8:33 pm

DL1DBY wrote: ↑

Mon Nov 09, 2020 4:40 pm

I just managed to repair one of my bad RD-5R. It went from BER 13.7% to BER 0.3% and no more reboots with high audio volume. The radio had bad solder connections on the power transistor module (marked as H0606E JC1728, middle pin) and on the audio amplifier chip (marked as TDA2822, Pin 8 ground). I just resoldered these connections.

That's interesting to know.

Thanks for posting.

I now also resoldered ALL the pins of the power transistor module (marked as H0606E JC1728) and of the 4-pin module next to it (of unknown function, driver?, no markings on it). Though all of the SMD parts were machine-soldered in it was obviousy worse than soldering by hand. For this reason in faulty units all other solder joints should be visually checked, especially ground connections. Use flux when resoldering and remove flux afterwards.

The RF and other hardware in this nradio is much worse than the GD77 or the DM1801

The GD77 has separate Tx and RX sections for VHF and for UHF. The RD5R just has one wide band RF section for 100Mhz to 600MHz, with a low quality switchable output filter for UHF.
The spectrum analysis of the RD5R show its RF output is not clean

Its internal voltage regulator is too small and the voltage on the internal bus varies so much that the keypad LEDs flicker a lot when transmitting on DMR.

It also does not have a power management IC, so the software can't turn off the radio if the battery goes flat, and this will damage the battery.

Also, because it does not have a power management chip, the settings need to be constantly saved to EEPROM, whenever the frequency or mode etc is changed. Which slows the radio down and will eventually wear out the EEPROM

I would not recommend this radio.

Buy a GD77 , or perhaps a DM1801. But the GD77 is definitely the best radio