FM Stereo/LW/MW/SW-SSB PLL Synthesized Receiver PL-880

A number of non official, non-documented, hidden, additional features have been disclosed as available on some of the model revisions, namely when they have firmware version 8820 installed. The following list covers those and other overlooked features.

#	Feature	Power state	Key	Band	Procedure
1	Enable additional features	ON	"4"	AM LW SW	To be able to enable Muting Threshold and DNR, enable this option. Select "AM" or "SW", press&hold key "4" until "ON" or "OFF" is shown.
2	FM de-emphasis	ON	"5"		Select "FM", press&hold key "5" until "50" (Europe) or "75" (USA) is shown.
3	Dynamic Noise Reduction	ON	"6"		Enable additional features (see #1). Press&hold key "6" until "ON" or "OFF" is shown; press key "6" to change (500Hz narrow band filter is not available when DNR is enabled)
4	Line Out level	ON	"7"		Select "AM" or "FM". Press&hold key "7" until the current level is shown; use Tuning knob to adjust the required value (30 to 63). Not available on SW band.
5	Muting threshold	ON	"9"	AM FM	Enable additional features (see #1). Select either "FM", "AM", "SW" or "SSB" (dedicated threshold levels for each). Press&hold key "9" until the current threshold level is shown; use Tuning knob to adjust it (00 to 40 dBu where 00 disables muting); press key "9" to change.
6	Center calibration and/or SSB zero beat calibration	ON	"0" and/or  "Snooze"	AM(MW) SW	Tecsun method: Select either LSB or USB; tune to a AM broadcast station and zero-beat using Fine Tuning for minimal distortion and audio is natural; if the last 2-digits of frequency are not "00", press&hold key "Snooze" to calibrate it where "00" will be shown when completed. Alternative method: Press "Display" to show the signal indicator; select either "AM" or "SW"; press "USB"; press&hold key "0" until a 2-digit number is shown blinking as well as the Hz digits of the tuned frequency; release key "0"; use Fine Tuning to adjust; press key "0" to set; repeat the above for "LSB" mode; check to have the same tone when tuned to nnn.95 USB and nnn.05 LSB; repeat the above as needeed. Note on AM/MW weak reception due to off-center calibration: According to Bill (Radio-TimeTraveller), additional +5 to +6dB can be acquired by using the fine tuning knob to tune around the radio station known frequency. In his radio the center frequency on MW is off by 2kHz, as on each station he needed to tune up 2 kHz. This issue seems to be unrelated to the SSB calibration.
7	Bandwidth scrolling	ON	"AM BW"		Press "AM BW" and immediately use either the Tuning or Fine Tuning knobs to scroll through the values.
8	SSB Sync Detetion	ON	"USB" "LSB"		Press&hold either key "USB" or "LSB" until "SYNC" is shown; press the same key to disable it.
9	External MW/LW antenna	ON	"AM"	MW	A Reset may be required. To use this feature, tune only upwards, so tune the station before proceeding. Toggles between internal magnetic antenna and external SW antenna socket. Press "AM" and tune to a station; press "USB"; press "AM" (if LW is enabled, press "AM" again); press "USB"; press "FM"; press "USB"; press "USB"; switch between internal or external antenna pressing "AM" or "SW". To return to normal, tune down.
10	1 kHz bandwidth filter	ON		MW SW	Enable additional features (see #1). Select the required SW band. Set the Muting threshold (see #5) to 13 or above; disable additional features (see #1); enable additional features (see #1); press "AM BW" to see the 1 kHz filter; it will be enabled until "AM BW" is pressed again;
11	FM range	OFF	"1"		Press&hold key "1" until 88-108, 76-108, or 87-108 MHz is shown; press key "1" to set.
12	LW band	OFF	"2"		To enable/disable LW band, press&hold key "2" until "ON" or "OFF" is shown.
13	MW 9/10 kHz steps	OFF	"3"		To set the MW tuning step, press&hold key "3" until "9kHz" or "10kHz" is shown.
14	Battery low voltage shutdown	OFF	"4"		Press&hold key "4" until the current low voltage shutdown limit is shown; use Tuning knob to adjust the value (3.4 to 3.7 Volt); press key "4" to set.
15	LCD backlight	OFF	"5"		Toggles the backlight between "ON (Auto Off)" or "OFF". Press&hold key "5" to toggle between "ON" (same as Auto Off using the slider Switch) and "OFF" (backlight turned off).
16	Show Seconds		"8"		Press&hold key "8" until Seconds digits are shown on the clock.
17	Firmware version	OFF	"AM BW"		Press&hold key "AM BW" until all LCD segments are lit; press key "AM BW" to show Firmware version (8819 or 8820); press key "AM BW" to show the Firmwaree release date using dd-mm-yy format (recent chassis revisions will not show the date).
18	Runtime since battery charge/Reset	OFF	"VF/VM"		Press&hold key "VF/VM" until the runtime is shown since the last time the battery was charged or since the last time the radio was reset.
19	Days since first power ON	OFF	"VF/VM"		Press&hold key "VF/VM" until the runtime is shown; press key "VF/VM" to show the number of days (upper right) since the radio was new and battery was first installed.

 

Jose Mesquita, 03.Jun.22

Weitere Posts (1) zu diesem Thema.

The Tecsun PL-880 uses two PCB assemblies:

• MCU/DISPLAY/KB PCB Assembly identified as "PL-880-B-REV.n"
• Receiver PCB Assembly identified as "PL-880-A-REV.n"
  • where "n" is the release number.

The followwing partial parts listing with remarks covers the PCB assemblies for the MCU "PL-880-B-REV.10" and Receiver PCB "PL-880-A-REV.12". Component labels of MCU PCB are prefixed with "2" as seen on the board silkscreen labels.

 

MCU PCB "PL-880-B-REV.10"

• Power Control
  • 2D2    BAS140W schottky diode - From VCC to IC3
  • 2IC3    RH5Z27CA? 3-pin smd LDO power regulator - From VCC to Power lines
  • 2Q5    SE2301 3-pin smd MOSFET - Switch Power on/off
  • 2D1    LED LCD backlight
  • 2Q2    S9014 3-pin smd npn - Switch for 2D1 LED on/off
  • 2C4    Super Capacitor

• DSP processor
  • IC4    Si4735-D60 DSP receiver - FM RF signal decoding, MW/SW 10700 kHz IF signal decoding

• MCU Processor
  • 2IC1    R5F2L38ACDFP Renesas 96KB ROM, 1KBx4 Data Flash, 10KB RAM, MCU processor in 80-pin PLQP0080KB-A smd package
  • 2IC2    BL24C256 256Kbit Serial EEPROM  8-pin smd

 

Receiver PCB "PL-880-A-REV.12"
 

• RF Front-End
  • D1, D2    1N4148 diodes - Antenna over-voltage protection
  • Q26    BF510 3-pin FET smd - MW RF front-end
  • Q4    2SK2394-Y7 3-pin FET smd - SW RF front-end
  • D6, D5    1SS135 smd diodes - Join MW RF andd SW RF signals to send to 1st Mixer 
  • Q6, Q5    L8050HQLT1  3-pin smd npn - Enabless "DNR1" AGC line to control RF gain by inserting C12 between D6,D5 outputs and ground.  

• 1st and 2nd Mixers
  • Q7, Q8    2SK2394-Y7 3-pin FET smd - 1st Mixer with 55845 kHz IF output
  • Q9    BF510 3-pin smd - 2nd Mixer with 10700 kHz IF output
     
• 1st Local Oscillator
  • Q16    BF510 3-pin FET smd - Oscillator
  • Q17    2SC3356 3-pin npn smd - buffer
  • D9, D10    1SV101 smd varicaps 

• 2nd Local Oscillator
  • Q13    2SC3356 3-pin smd npn - Oscillator
  • 1X2    45.145 MHz xtal
  • D11    1SV101 varicap
  • D12    BB133 varicap

• PLL Synthesizer
  • IC6    MB15E03SLPFV1 16-pin smd - PLL Synthesizer
  • 1X3    7.200 MHZ xtal

• Dynamic Noise Reduction (DNR)
  • Q12    2SK2394-Y7 3-pin FET smd - 10700 kHz IF buffer 
  • IC4    CXA1691AM (CD1691CB) 28-pin smd AM/FM radio - Receives MW/SW 10700kHz IF signal, outputs AGC voltage at pin 22 marked as "DNR1" to control the gain enable a low pass filter on the RF Input front-end.
  • Q20, Q21    S9014 3-pin smd npn - Together with VR3 500K pot, receives "DNR1" AGC and outputs distinct AGC level marked as "DNR2" to control filter response of the Audio Amplifier.  
  • 1X5    10.245 kHz xtal
  • LBQ1    455 kHZ filter

• DC-DC Converter for tuning voltage
  • Q23, Q24    S9014 3-pin npn smd - Oscillator, using transformer T881
  • D8    1N4148 smd - HF rectifier 
  • D7    16V Zener diode smd - Regulation

• Power Supply 
  • D4    1N5819 schottky diode - From USB Power to VCC line
  • Q20    2SJ245 3-pin smd MOSFET - Switch from BATT power to VCC line
  • BT1    3.7V Battery
  • Q14    SE2301 3-pin smd MOSFET - Battery charger circuit
  • IC1    MCP73831 (or equiv.) 5-pin smd SOT23-5 - BT1 Battery charger 
  • IC2    RP114N281D 5-pin smd  LDO 300mA, 2.8V power regulator
  • Q10    SE2301 3-pin smd MOSFET - Switch to SW-Power
  • Q11    SE2301 3-pin smd MOSFET - Switch to MW-Power
  • Q2    SE2301 3-pin smd MOSFET - Switch to Audio Amp section

• Audio Amplifier
  • IC8, IC9    TC4W53FU 8-pin smd 2-Channel Multiplexer/Demultiplexer - Switch between AM or FM distinct high pass filters.
  • IC5    CLC2011 8-pin smp 2-channel opamp - Audio pre-amplifier (approx. gain of 5); receives L/R audio from the DSP IC via IC8/IC9 to drive IC7.
  • IC7    SP2068EF(APA2068) 16-pin smp 2-channel audio power amplifier - Earphones (2-ch/stereo) and Speaker (bridged mode).
  • Q18, Q19    S9014 3-pin smd npn - Enables "DNR2" AGC to control audio low pass filter shape by inserting C59/C57 (22nF) on RC networks at IC5 outputs.

• Line Out
  • IC3    CLC2011 8-pin smp 2-channel opamp - Line audio amplifier (approx. gain of 6); receives L/R audio from the DSP IC to drive the Line Out socket.

 

Jose Mesquita, 02.Jun.22

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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. 

 

 

Jose Mesquita, 01.Jun.22

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