KDK/KENPRO FM-240
Mono-Band (2m, VHF) FM Mobile Transceiver
Overview:
- VHF: 2 meter band
- 0.15 uV sensitivity (12 dB SNR)
- Output power (factory settings):
5 W (low); 25 W (high)
- CTCSS Tones
- 1750 Hz Burst Tone
- 16 Memories + Call Frequency
- 2 VFOs
- Complete Alignment
- Fully cleaned
- Fresh painting
This Kyokuto Denshi Co. LTD / KDK / KENPRO FM-240 VHF, FM mobile transceiver was bought in unknown condition. It had damaged backlight, old thermal compound in the power module, a bad power lead, worn coaxial cable, , in refurbished/restored condition. You can find the detailed specifications and the service report below.
Perfect working order (see test results below) and very good cosmetic appearance (has just been re-painted).
Please check the pictures and the 4 video episodes.
Original Specifications:
GENERAL:
Frequency range (transmission and reception): 142 - 150 MHz
VFO Step Sizes: 2.5 - 40 kHz, programmable (x10 with speed option ON).
Memories: 16 plus CALL. All programmable.
Band Scan: Programmable limits and modes: CARRIER, AUTO, DELAY. Scan step is the same as the VFO step.
Memory Scan: Programmable modes (SKIP, CARRIER, AUTO, DELAY)
Mode (Emission Type): FM (F3E)
Antenna Impedance: Unbalanced feed, 50 Ohm nominal.
Supply Voltage: 13.8 V +/- 15 %. Negative Ground.
Consumption:
Transmit: 1.5 A @ 5 W; 5.5 A @ 25 W
Receive: 0.4 A - 0.6 A (max volume)
Temperature Range: -10 ºC to 60 ºC
Dimensions: 140 (W) x 40 (H) x 170 (D) mm, body only
Weight: 1.0 kg (body only)
TRANSMITTER:
Output power: 5/25 Watt (Low/High), factory setting.
Modulation system: variable reactance frequency modulation
FM Deviation: +/- 5 kHz
Spurious emissions: less than -60 dB from carrier
Duplex Offset: Programmable from +/- 0.1 to 12.7 MHz (factory set to +/- 0.6 MHz)
Tone: Programmable from 67.0 Hz to 250.3 Hz (34 EIA Tones)
RECEIVER:
Receive system: double-conversion superheterodyne
Intermediate frequencies:
1st: 10.7 MHz
2nd: 455 kHz
Sensitivity:
Better than 35 dB S/N ratio @ 1 uV
Better than 12 dB SINAD @ 0.2 uV
Squelch Sensitivity: Less than 0.15 uV
Bandwidth: 6 kHz @ -6 dB
Selectivity: More than 12.5 kHz @ -60 dB
Image Response Rejection Ratio: Better than 70 dB.
Audio Output Power: More than 2 W at 10% THD with a 8 Ohm load
Audio Output Impedance: 8 Ohm
Reverse Duplex Option: Transmit and receive frequencies are reversed
STANDARD ACCESSORIES (from factory):
Speaker Microphone:
Speaker: 8 Ohm.
Microphone, Condenser type:
SM-34J: UP/DOWN buttons only.
SM-34J: UP/DOWN buttons plus 1750Hz tone burst.
SM-34J: UP/DOWN buttons plus DTMF tone encoder.
Power Cable: 2 meter long, with 7 A fuse.
Spare Fuse: 1 piece, 7 A.
External Speaker Plug: Miniature phone plug type, 3.5 mm.
Mobile Mounting Bracket: 1 piece, black.
Mounting Hardware
Instruction manual, including schematic diagram.
Service Report
Date: 2020/09/08
Equipment Identification:
Make: KDK (Kyokuto Denshi Co. LTD)
Model: FM-240
Serial Number: 002402
Type: Mono-Band FM Mobile Transceiver: VHF (2 m)
Supplied With/Extras:
- Tone Squelch Unit (used in the transmission of sub-audible tones for repeater access and for the tone squelch function). Voice synthesizer module not installed.
- SM-34E Hand Microphone (electret condenser type)
- Non-original mobile mounting bracket + 2 screws
- Specially manufactured double-fused DC lead (7.5 A fuses)
Service Description:
- Correction and painting of the covers and heatsink.
- Improvisation of a mounting bracket (non-original).
- In-depth cleaning and polishing of the front panel and microphone.
- Overall cleaning of the PCBs and components.
- Replacement of the LCD back-light bulbs (one bulb was burnt) with high brightness dark-orange LEDs.
- Replacement of the thermal compound on the RF power module.
- Complete alignment as per the service manual.
Alignment Description and Results:
- PLL local oscillator (118.3 MHz) amplitude maximized.
- VCO lock voltage adjusted.
- Input to PLL: RF amplitude maximized (TX and RX).
- Frequency calibration (reception): 133.300 MHz ± 1 Hz.
- Frequency calibration (transmission): 144.000 MHz ± 4 Hz.
- 5 kHz calibration (reception): 133.305 MHz ± 1 Hz.
- 5 kHz calibration (transmission): 144.005 MHz ± 1 Hz.
- Confirmation of frequency in the whole range of the VFO: ± 120 Hz (maximum deviation of the frequency from the value displayed on the screen)
- Verification of the 2nd local oscillator frequency: 10.245023 MHz. OK (the tolerance is 200 Hz).
- Peak tuning of the RF amplifier section.
- S-meter adjustment: full scale (S9 + 20 dB) = 10 uV.
- Squelch sensitivity: 0.24 uV opens the squelch.
- Reception sensitivity check: 0.15 uV at 12 dB SNR.
- Transmission power peak tuned (VC2 and VC3).
- Transmission power adjustment (High/Low): 25 W / 10 W
- FM deviation adjustment: ± 4.8 kHz (1 kHz, 25 mV microphone audio level)
- Tone squelch unit level tested on the air: OK.
- Adjustment of alarm signal level (was too loud).