tecsun: Tecsun PL-880 - Hardware and Firmware versions

Introduction on the reported issues for the PL-880

The PL-880 is a PLL triple conversion superheterodyne with digital signal processing (SiLabs 4735-D60) decoding on Amplitude Modulation (AM) bands. FM band is handled directly by the DSP.

I have been following the reports of owners, testers and modders concerning some alleged issues discovered since the model was relased back in 2013 up to present day (june-2022).

Most of the issues have been worked out by Tecsun (firmware and hardware updates) and Silicon Labs (DSP 4735 firmware). 

One major issue has been reported for the usage of SSB, where audio distortion is experienced when using LSB/USB under certain signal level conditions, alleged caused by AGC bad behavior. 

As the AGC function is implemented inside the SiLabs 4735 DSP integrated circuit, it seems that Tecsun was having a hard time minimizing the issue, after having released several harware versions of the Mainboard PCB assembly and at least two official firmware versions. 

Some owners tell us that different behaviors have been discovered for the same displayed firmware version, so Tecsun may have been releasing "silent" updates on different production batches. Also the later production releases only shows the firmare version, omitting the release date.

Currently there is no consensus from buyers concerning the SSB issues being fixed or pending. Some say the issues are there, others comment that the problem was fixed. As Tecsun released so many different hardware and firmwware versions it is possible that some vendors still sell the older batches, but there is no positive confiormation that the issue was fixed and for what hardware/firmware version.

Due to the above PL-880 behavior, many prefer the PL-660 or PL-680 double conversion pure analog/PLL designs for SSB listening . I have the PL-680 but do not have the PL-880 yet.

Additionally, the USB/LSB Sync Detection is not officially available on the PL-880, but a non-documented key combination would enable it, despite Sync detection is not really properly working on this model.

To display the Firmware version and release date, with the radio powered off, press and hold the key "AM BW"  until the LCD shows all segments lit, then press and hold the same key to show the Firmware version, at last press and hold the same key to show the date (day-month-year format).

 

Hardware and Firmware versions

Following is a list of hardware and firmware releases that I found in publications of owners/testers/modders along the years. I could not find evidence of newer versions after 2018.

MCU/DISPLAY/KB PCB assembly H/W revisions

• PL-880-B-REV.7     2013-07-06    
• PL-880-B-REV.10   2014-01-15   MB15E03

Receiver PCB assembly H/W revisions

• PL-880-A-REV.6        2013.05.25   
• PL-880-A-REV.7        2013.07.06
• PL-880-A-REV.10      2014.01.15    MB15E03
• PL-880-A-REV.12      2014.07.28    MB15E03/BF511
• PL-880-A-REV.13      2016.10.12    MB15E03/BF511  
• PL-880-A-REV.15      2018.04.10    MB15E03/BF511 

Firmware versions

• Year 2013, Version 8819, Date not collected
  • But reported for Receiver PCB REV.7 (2013.07.06)
  • Known bugs
    • B1 - Muting threshold can not be properly adjusted
    • B2 - Bandwidth can not be adjusted using the tuning or fine tuning controls. You can only cycle through filters by continuously press the AM BW button.
    • B3 - Instability/distotion on SSB and a useless Sync Detection.
      • Frequency modulation of the tone when the signal is strong, especially on CW
      • Amplitude distortion caused by the AGC inside the DSP chip - on cw / ssb is the agc attack being too slow.
    • B4- Tune backward when using the Fine Tuning knob in SSB mode

• Year 2013, Version 8820, Date of 131113 (13-nov-2013)
  • Fixed bugs
    • B1. B2, B4

• Year 2015, Version 8820 but F/W was silently changed, Date is not shown anymore
  • ​Reported for Receiver PCB REV.10, date of 2014.01.15
  • Fixed bugs
    • B3 - Instability/distotion on SSB and a useless  Sync Detection - Significantly improved version, SSB is quite acceptable now (although, no comments on Sync Detection).

 

Some details on the different PCB revisions

The step in the 1st local oscillator was 2kHz on the initial Receiver PCB releases like the PL-880-A-REV.6 (2013.05.25) using the LC72137 PLL Synthesizer. Later Receiver PCB releases, at least from PL-880-A-REV.10 (2014.01.15), uses the MB15E03 PLL Synthesizer (position IC6) for 1kHz steps.

Starting with Receiver PCB PL-880-A-REV.12 (2014.07.28), the LW/MW band front-end was added with a BF511 FET (position Q26) to amplify the Magnetic Antenna signal.

Starting with Receiver PCB PL-880-A-REV.10 (2014.01.15 MB15E03) and up to PL-880-A-REV.13 we see two additional  TC4W53FU 2-Channel Multiplexer/Demultiplexer IC's (positions IC8 and IC9) in the Audio Amplifier section to set separate high pass filters for AM and FM.

• However, someone reported that in his PL-880-A-REV.15 the IC8 (audio left channel) was left blank in the PCB. This looks like a production fault than anything else. 

 

To thank the Author because you find the post helpful or well done.

I acquired my new unit in April-2022. After opening it, I verified that a new Receiver PCB assembly was released:

• PL-880-A-REV.16      2019.12.16    MB15E03/BF511 

The firmware version still shows 8820 and the Date is not displayed.

 

To thank the Author because you find the post helpful or well done.