Questions and Answers 

1) Radtel RT-4D

1. Q: 

   RT-4D device cannot connect to hotspot (but repeater works fine), how to solve it?
   Description:
   User encountered the following problems when setting up RT-4D:

   1. The device cannot activate hotspot and cannot connect to Brandmeister network, but repeater works fine.

   2. The latest firmware, DMR chip and CPS software have been updated, and the hotspot and other devices are confirmed to be normal.

   3. Other users have also reported similar problems (RT-4D compatibility issues with hotspots).
   A:Solve problems with precise frequency calibration
   

   Cause Analysis:
   The connection problem between the device and the hotspot may be caused by frequency offset. Even a small deviation (such as ±0.2 kHz) may prevent the device from syncing with the hotspot.

   Solution steps:

   Get the debugging tool:

   1.If you have a frequency detection instrument (such as a professional SDR or frequency meter), contact technical support to obtain the debugging software.
   Accurately calibrate the frequency:

   2.Open the debugging software and adjust the frequency offset value as instructed to ensure that the error is within ±0.2 kHz.
   Focus on checking whether the transmit/receive frequency of the device and the hotspot are exactly the same.
   Complete debugging and restart:

   3.Click "Finish" in the lower left corner of the software interface to save the settings.
   Power off and restart RT-4D to apply the new configuration.
   Verify the connection:

   4.Try to connect to the hotspot again to confirm whether it is successfully connected to the network.

   2. Q：I tried to update the firmware, but, when the tool showed the "finished", the radio restarted and it's now stuck on the RADTEL boot screen. What can I do?
       A:There are several solutions. One is to remove the battery, put it aside and wait for a few minutes before reinstalling it and turning it on. Another is to turn it on with the menu key. Try it several times. If it doesn't work, then re-upgrade the digital firmware.
   3.Q:I recently bought a 4D and updated it but now it only shows a green light, no audio or display. I have tried flashing the firmware and the DMR chip but that didn't work - I have also tried the reset method - can you help?
   
   A:This is data loss. If you have flashed the latest firmware, you can press and hold the 0 key to start the machine, and then wait for a few seconds, the machine will automatically restore the data.
   

   3.Q: How to upgrade the firmware? How to upgrade the DMR firmware?
   A: To update the firmware, you always press and hold the PTT button to turn on the machine. The machine will light up green and then upgrade. It will automatically restart after the upgrade. To upgrade the DMR firmware, use the Browse button to select the file, select the port, and the baud rate of 115200bps, then click the Burn button, and then press and hold the Menu button of the walkie-talkie to turn on the walkie-talkie. At this time, the update will begin. During the update, do not operate the computer to do anything else, and keep the update window in the front. The update will be completed in about 140 seconds. If it takes much less than this time, the update will fail and you have to start over. After the update is completed, it will not automatically restart and you need to restart manually.

2)Radtel RT-880

1.Q:Why do I need a password to download the cps and firmware of Radtel rt 880?
A:We currently only provide firmware and CPS software to consumers who have purchased our Radtel RT-880, so please contact me via WhatsApp and email and send me your order screenshot or order number directly. We will provide you with the password after verification.
2.Q:How to enter the CB band?
A:If it is a two-way radio, Basic Settings->17 Work Range->18-64MHz, after confirmation, the machine will automatically restart and you can enter directly. If you listen to 2-30MHz broadcast radio, or shortwave LSB USB CW signal, you need to enter the radio mode, long press the # key to switch the frequency band, and short press the # key to switch the mode.
If you think this operation is too troublesome, you can consider holding down the ▼ key to turn on the machine and turn on the full-band debugging mode. At this time, you don’t need to enter the menu to switch the frequency band, you can directly enter the CB band frequency, but remember to replace the antenna, otherwise the transmission may cause damage.
3.Q:Have a question about squelch. Even at the lowest setting (1), the squelch does not open even when the signal is strong (S +10). There is noise at S6.
When I open the squelch manually with the side button, the signal can be heard. I tested it several times on the 2 meter band 144.500 MHz.
Any suggestions?
A:Analog Settings->Glitch TH setting, adjust it higher, it may be set to 0
4.Q:I have a new RT-880 that seems to have a SW mode defect. I loaded firmware v1.06A20250417. There are loud clicking noises faster than 1/second. This happens with or without a SW antenna, at home or away, in AM, USB, and LSB, and on all the frequencies I've tested. Is there any setting to check, or is this unit defective?

A:Analog Set->RSSI Refresh value should be increased
5.Q:How can I edit the Chinese text on the blue banner in high frequency mode?
A:In the menu, select "FM Radio->CH List" to find the channel corresponding to the Chinese characters, then press the Menu key to enter, and then select "Edit Name". After the change is completed, return and select the second option "Set As Current" to set it as the current channel.
6.Q:I checked the power and it's nowhere near 10 watts. Is this correct?
A:To measure on full battery, VHF should be 8-9W, UHF should be 7-8W, CB band should be lower at 2-3W
7.Q:Hi, is there any special tips for using this radio? It only shows a variable frequency oscillator (VFO) and all buttons are inoperable and cannot transmit. Is there a forced restart operation required? Is there a problem in the radio? I put the battery in and out and tried several times, but it still doesn't work!
A:Update the latest firmware, re-edit the frequency with the latest CPS, pay attention to the complete frequency points, and check the last 3 VFO channel data in the channel table to ensure that they are not missing

8.Q: Multi-wait and cross-band transmission will be disabled’ Please help me understand this sentence. Does this mean that we can’t standby on three frequencies and can only listen to one frequency, even if we have three different frequencies displayed on the screen
A: Yes, this is disabled after turning on the full-band debugging mode, because our 27M and UV bands are completely isolated by relays. If you can still standby or cross-band transmission in full-band mode, someone will let the machine standby on 27M and UV bands at the same time, causing the relay to switch back and forth between the two frequency bands, and there will be a constant "click-click-click" relay switching sound, and it will soon cause the relay to be damaged so that the signal cannot come in

9.Q: Please tell me how to set the menu to English (Chinese is on the horizontal blue bar).
A: This is the channel name, which can be changed at will, in Chinese, English or other characters. Just change the channel name of the radio by programming the frequency, or go to the List item of the FM Radio menu, find the channel with the Chinese name, click it, Edit Name to change the name, then return to the previous level, select Set As Current and it will be changed.

10.Q: Hello, the device cannot send aprs beacon. The carrier with the beacon was sent, but there was a problem with the carrier and the encoding could not run properly.
Either the firmware 1.10 still has errors or the device is defective.
Do you know of any cases where there are defects in APRS devices?
A: First go to the APRS menu and reset APRS, then reset it again

11.Q: Is the CB band antenna an SMA female or SMA male? Which output is on the radio (CB)? Is it the one under the cover? Thank you.
A: The antenna interface can be found on the machine. All transmissions are on the left antenna port, and the FM64-108MHz of the radio is also on the left antenna port. Only the shortwave, medium wave, and long wave reception of the radio uses the middle antenna port.
12.Q: I have an RT-880G and I'm having a weird problem that I can't seem to fix. I seem to have to turn the radio on before I can receive anything on the repeater channel, and once I start receiving, the radio will only receive for about 10 seconds before it loses power again and I have to turn the radio back on. Do you know what might be going on? I think I've changed every setting I could. I even tried reinitializing the radio (using the menu options) but that didn't seem to reset anything?

A: Go to the menu, time management, APO options and see if it's on, if so turn it off

 13.Q: Is it possible to put all 3 frequencies in vhf/uhf mode, or is the highest frequency only used for hf?

A: The frequency band switch is in the Basic Settings->Work Range menu

14.Q:1.When you put the radio in FM radio mode, can you scan the frequency range, such as the 80-meter band of 3.720MHz. Is there a way to go up or down?

 A:In radio mode, long press the * key to scan, any key to exit scanning, long press the 0 key to switch the scanning direction up or down

15.Q: I can't update because the radio is frozen, and pressing the MENU button doesn't work... and only one channel is displayed on the screen

 A: Turn off the radio first, hold down the PTT button to turn it on, and enter the upgrade mode indicated by the green light. This can be entered. Update the latest firmware, and then press the MENU button to turn it on to restore the data

16.Q:1.The temporary setting function is not clearly described, especially the temporary reception (RSSI and noise). 2.In the description of firmware 1.10, it is written that the temporary TX function is turned off, in fact, when this setting is changed, a power change occurs3.The reverse CH function does not work. This function does not work in firmware 1.06, 1.07, 1.09 and 1.10. 3.Please change the lock and enable repeater icon from red to a lighter color. Red is unreadable in sunlight, and it is not clear whether the repeater is turned on. It is recommended to increase the brightness of the display,4.When the detect frequency function is enabled, only 136-174 and 400-480 can change the range. For some reason, if you press the "" key, the other ranges will not be enabled. In the 860 model, you can select different scan areas, and in the 880 model, you can select two scan areas.
A:
1. This is a temporary debugging function set. After it is turned on, it will no longer be based on the factory debugging data, but will be based on the data written in the menu. It is for some customers who have instruments and equipment and want to test the machine's limit values. Ordinary customers are not recommended to turn it on, which may cause damage to the machine.
2. Reverse CH means changing the switching direction of the up and down keys in channel mode, and the frequency mode is invalid.
3. The next version will update all red icons for easy display
4. In the current version, it is changed to short press the # key to switch between 136-174 and 400-480, and long press to switch between the full frequency band.

3)Radtel RT-860
1.Q: I have a Radtel860, and there is no option 5 on its menu. There are only 4 options for Sistem Time, which is what the manual says. I use version 1.6. I saw a video of Radtel860 on YouTube, which had a Site Time option, but mine does not have it.
A: Option 5 is the system time, but it was later cancelled because customers complained that the time could not be saved. This is because the hardware does not support saving time.
2.Q: My 860 started flashing orange and blue when charging. Does anyone know what this could be? Now I am not getting any charging indication at all. Tried multiple chargers. It acts like it is running low on supply. Tried different batteries in the radio, same result, no charging.
A: The flashing orange and blue light is the reason for no battery being detected, in this case, it could be an open circuit or a bad battery.

4)Radtel RT-900

1. RF Front-End Chipset:
– Does this RT-900 device use the Beken BK4829 (or other Beken) RF chip?
– Does it have one or two RF chips inside (i.e. single or dual Beken/BK series chips)?
– Do all current devices use these chips? Or are there multiple hardware versions?

A: BK4829 for Bluetooth version, BK4819 for standard version

2. Main Microcontroller (MCU):
– What microcontroller does this device use?
– Is it an Artery AT32 MCU or another type (e.g. Nuvoton, Hangzhou, or similar brands)?

A: Jie Li chip for Bluetooth version, Cortex-M0 chip for standard version

3. Hardware Version:
– Does the device I received have a specific hardware version number?
– How can I confirm my version number (e.g. internal label, firmware ID, etc.)? A: The menu contains the software version number and the hardware version number

4. Receive function:
– Is the RT-900 a single receive or a true dual receive?
– Can the device receive on both A and B channels at the same time? Or can it scan/switch between A and B channels?

A: Single receive, not simultaneous, just switching between A and B channels

5. Performance differences (if any):
– Are there any performance or functional differences between the old and new hardware batches (e.g., in selectivity, squelch behavior, or audio processing)?

A: No

6. Audio processing and DSP:
– Does the RT-900 include any form of digital audio processing (DSP) for noise reduction, audio leveling, or clarity enhancement?
– In addition to the basic squelch function, are there any other audio filtering or enhancements applied?

A: The Bluetooth version has noise reduction, the regular version does not

7. Filtering and selectivity:
– What is the receiver selectivity (adjacent channel rejection) in dB?
– Are any forms of SAW filters, ceramic filters or digital filters used in the receive chain?

8. Harmonic Rejection and Transmitter Cleanliness:
– Are there lab-tested values for harmonic rejection, spurious emissions and modulation bandwidth?
– Does the RT-900 transmit quality comply with FCC Part 90 / CE / PMR specifications?

A: FCC certified

9. Frequency Range and Modifiability:
– What is the specific receive and transmit frequency range supported by the RT-900 out of the box?

A: 4819: RX:18-660/840-999, TX: RX cut out (108-135) 4829: RX:18-580/760-999 TX: RX cut out (108-135)
– Does the RX or TX support (natively or via modification) the CB frequency (approximately 26-28 MHz)?
– Are there any hidden or extended bands that can be unlocked via software?

10. TX Power Control:
– The product is rated at 8W, but what is the actual TX power output in different bands (VHF, UHF)?
– Can the TX power be manually limited in the settings (e.g., to 5W, 2W, 0.5W)?
A: Yes
– If so, what is the available power level for each band?

11. Firmware Information:
– Which firmware version is pre-installed on my device when it leaves the factory?
A: The latest version of the current time period is pre-installed when it leaves the factory
– Can more bands or features be obtained through firmware updates?
A: Yes
– What new features, bug fixes, or improvements does the latest firmware contain compared to the original version? 1. RF Front-End Chipset: