shenzhen-d: DEGEN DE1105 - Component details
shenzhen-d: DEGEN DE1105 - Component details
The Degen DE1105 design uses double heterodyne conversion on AM bands (MW and SW) and single conversion on FM band. The IF are:
- FM: 10.7 MHz
- AM 1st IF: 28.000 MHz
- AM 2nd IF: 450 kHz
The AM 1st IF is therefore above the upper SW band limit of 26.100 MHz.
The radio uses two PCB assemblies:
- MCU PCB.
- So far only one PCB version is known
- DE1105S-1 REV.0.10 2005.07.04
- At least two MCU Processor versions exist
- DE11S-MCU 2007.05.14
- DE11S-MCU 2009.05.27
- So far only one PCB version is known
- Receiver PCB
- So far only one version is known
- DE1105M-2 DEGEN 0120
- So far only one version is known
The built-in speaker is a 12Ω 0.25W unit.
The two PCB assemblies are interconnect with a flexible flat cable. The silkscreen labels for each pin at the connector are:
- vol
- mute
- ce
- al
- vcc
- power
- gnd
- gnd
- do
- bass
- st
- clk
- di
- pwm
- aga
- agc
- i/out
- i/out
- batt (+)
- batt (+)
The following component listings only cover the main devices.
Receiver PCB Ref. DE1105M-2 DEGEN 0120
Component side:
U3 TA7358AP - FM front-end
U4 65N4 - LDO Regulator, SOT-23-5 5-PIN IC SMD
Q9 K544E (2SK544E) - N-MOSFET VHF, Idss=2.5..6.0mA
Q17, Q27 YJ7 (2SK2394-7) - N-FET LN, HF, Idss=16..32mA, SOT-23
CF6 XTAL 27.550 MHz - Local 1st Oscillator for U2-AM_OSC
CF7 XTAL 28.000 MHz - AM 1st IF filter
CF3 CQ ZTB 456F16 - 456 kHz FILTER for U2-VCO
CF4 L10.7S - 10.7 MHz FILTER
CF2 L10.7S - 10.7 MHz FILTER
CF5 CQ R50I - 450 kHz 4+1 PIN FILTER for U2-AM_IF_IN
Less Components side:
IC1 CD1622CB (EQ CXA1622M) - Stereo power amplifier / mono BTL power amplifier;
U1 LC72122 - PLL Frequency Synthesizer 20-pin smd
CF1 XTAL - U1 Osc
U2 TA8132AF - 3V AM / FM IF + MPX
MCU PCB Ref. DE1105S-1 REV.0.10 2005.07.04
Component side partially covered with metal shield:
U101 DE11S-MCU 2007.05.14 - MCU Processor
U102 N14B - 3-PIN SOT-23 SMD Voltage detector IC 1.4V, - Reset
U103 ATMLH736 - SOP-8 SOIC-8 Atmel 2048 x 8 (16K) SPI EEPROM, 1.8v TO 5v,
U104 65P 0 (also seen as 2C0) - 5-PIN SOT-25 SMD LDO regulator 2.2V, 300mA XC62H series
Q101 NY - SOT-89 PNP power switching 2SA1213? 50v 2a 500mW
Q102 J6 - SOT-23 NPN general purpose switching
Q103 J6 - SOT-23 NPN general purpose switching
Q105 J6 - SOT-23 NPN general purpose switching
Q106 M6 - SOT-23 PNP general purpose switching
Q107 J6 - SOT-23 NPN general purpose switching
D100 C3 - SOT-323 dual fast switching diodes
D101 C3 - SOT-323 dual fast switching diodes
Display/KB Side:
D117 LED display
D115 LED display
D120 LED keyboard
D119 LED keyboard
D118 LED keyboard
Note on schematic diagrams:
I could not find any complete circuit diagrams for this model. However the DEGEN DE1102 diagram is available for download and, while having different specifications namely a lower 10.7MHz 1st AM IF frequency (28MHz on the DE1105) or a manual Local/DX attenuator (Automatic attenuation adjust at the antenna input - AGA command) or a different PLL IC, is close enough to be used on the DE1105.
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shenzhen-d: DEGEN DE1105 - Component details
The 28 MHz seems a strange choice of first IF unless someone had huge load of very cheap 27.550 MHz crystals.
At the least I'd have chosen a European audio, Nicam or video IF frequency (32 to 39 MHz band). I think later USA sets used 40 MHz band.
But also maybe the main target market only allowed up to 26.10 MHz. CB bands are roughly 26.5 Mhz to 28 MHz (depending on country and era) and 10M Amateur is 28 MHz to 29.7MHz. A 10.7 MHz first IF for dual conversion on AM on an AM-FM set was a simple cost saving solution. Some earlier Sangean sets use about 56 MHz to 58 MHz depending on market, which seems curious compared to a 30MHz band 1st IF such as 33.5 MHz.
Thanks for the analysis.
To thank the Author because you find the post helpful or well done.