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Early Mizuho RigsMX Series HandheldsP seriesMX-606DTRX-100 and RX-100 Dentron MLX-Mini



Mizuho made a wide variety of station accessories for the QRP ham operator, shortwave/broadcast listener, and radio direction finding entusiast. The major items, such as antenna couplers and matching amplifiers for the Mizuho transceivers have their own pages. This page is dedicated to other station accessories, both those that match specific Mizuho rigs and those which are for more general use.

Please check back as pictures, specifications, manuals, and schematics will be added on a regular basis.

Accessories for the MX series handhelds

CW-2SMizuho CW-2S sidetone/QSK unit for MX series handheldsThe CW-2S is an external add-on for the MX-xxS series of HF and VHF SSB/CW handhelds. It provides sidetone and semi-QSK operation with an external key. Without a CW-2S the PTT button must be depressed to operate CW, which isn't exactly convenient, particularly when using an external key. The CW-2S turns the handheld into a very respectable little CW rig and is a must for the serious CW QRP operator who uses the MX-xxS series. The CW-2S has been marketed under both the Mizuho and JIM brand names. Units are identical otherwise.The CW-2S was initially offered both factory built and as a kit. Only factory built units have been available in recent years.CW-2S Schematic Diagram (PDF format)

MS-1 and M-4 Speaker/MicsMizuho MS-1 speaker/mic.The MS-1 and M-4 are two different styles of speaker/mics. for the MX-xxS series handhelds. The M-4 is wired for the older series of Pico transceivers (models MX-2, MX-6Z, MX-10Z, and MX-15 only), while the MS-1 is wired for the more recent series of rigs (models MX-xxS). The two mics. are not interchangable and are identical except for the wiring inside the molded plastic connector.Mizuho MS-1 wiring (GIF format)BM-6 and M-3 Soft Cases



BM-6 case on MX-21S transceiver


The BM-6 and M-3 are soft plastic cases for the Pico series handheld transceivers. The M-3 fits the MX-2, MX-6Z, MX-10Z, and MX-15. The BM-6 fits the newer MX-xxS models.PR-3S and PR-1 Mounting BracketsThe PR-3S is the system mounting bracket for the most recent generation (MX-xxS) of Pico tranceivers. It holds the HT, the matching PL series amplifier, and either a blank plate or the CW-2S. Together with the MS-1 it creates a complete mobile or mini-base station. The PR-1 is a similar mount for the MX-2, MX-6Z, MX-10Z, and MX-15. It holds the handheld, the matching amplifier, and either the VX-15 external VXO for the MX-15 or a blank plate.VX-15 External VXOVX-15 external VXOThe MX-15 is unique in that an external VXO option was made for it, allowing the use of more than two 50kHZ band segments without opening the radio to change crystals. Unfortunately this idea was not extended to other Pico transceivers.







AN Series AntennasAN-7 antennaMizuho offered loaded telescopic antennas for all the HF and 6m models of their Pico handheld transceivers. Antenna model numbers are consistent with transceiver model numbers. In other words, the AN-3.5 antenna matches the MX-3.5S transceiver while the AN-15 antenna matches the MX-15 transciever, etc...AN-3.5 80m Antenna Data Sheet (PDF format)

PM-1 DC-DC ConverterPM-1 DC-DC ConverterThe PM-1 DC to DC converter accepts 12-13.8V DC input and delivers 9.5V DC output to allow the Pico series transceivers and the P-7DX and P-21DX CW portable transceivers to be operated mobile or from a standard 13.5V DC power supply. The PM-1 was also offered by Santec under their JIM (Japan Information Medium) brand name with a charcoal grey finish (picture) to match JIM branded Pico transceivers.PS-2 Power SupplyThe PS-2 is a 9.5V 2A regulated DC power supply for use with the Pico handheld transceivers and P-7DX and P-21DX CW portable transceivers. It accepts 100-110V AC input for use with Japanese and North American mains power.




General Station AccessoriesAudio ProcessorsAP-1D Audio Processor
AP-1D Audio Processor

The AP-1D Audio Processor provides an external audio notch, peak, and bandpass filters. It has inputs for two rigs which can be selected by an A/B switch. The three filters can be used separately or in any combination. Notch filter frequency and depth are controlled independently. CW peak filter bandwidth is 40-50Hz at -6dB, and the peak frequency is adjustable between 500Hz and 1000Hz. The bandpass filter is fixed at a band width of 900Hz from the factory, making it usable both as a very wide CW filter or as a narrow SSB filter.The AP-1D matches the KX-3 Sky Coupler antenna tuner and the SX-3 preselector in size and appearance. The AP-1D was sold in North America by Ace Communications in North America in the early 1980s. It continued to be offered in Japan after Ace Communications went out of business.Specifications:Filter:

Narrow bandpass filter (PEAK): 500-1000Hz variable
Band pass filter (BAND PASS): 600-1500Hz fixed
Narrow band attenuator (NOTCH): 600-3000Hz variable
Input impedance and level: 2.5Kohm -30db
Output impedance and power: 8 ohm, 0.5W
Power requirement: DC 13.5V 150mA
Selectivity: Narrow band pass filter (PEAK): Over 25dB at 1 octave relative to center frequency
Band pass filter: Out of band attenuation at 1 octave over 10dB
Dimensions: 200mm W x 66mm H x 153mm D
Weight: 1.1kg Ace Communications spec sheet for the AP-1D and AP-M1, circa 1982 (JPG format)AP-1D Manual (PDF format).AP-M1 Audio ProcessorAP-M1 Audio ProcessorThe AP-M1 Audio Processor is a much smaller, simpler battery operated unit with a carrying handle for portable operation. The AP-M1 has just one input. It offers notch and bandpass filters but lacks the CW peak filter included in the AP-1D. However, the bandpass filter in the AP-M1 is adjustable, unlike the AP-1D. Band width and center frequency can be adjusted for both filters.The AP-M1 was also offered by Ace Communications.Specifications:Filters: Bandpass filter and notch filter
Center frequency variable between 400Hz and 4kHz
Bandwidth variable (at -12dB) between:Bandpass: 100Hz-10kHz or more
Notch: 70Hz-1500Hz

Input impedance: 8-600 ohms
Ouput impedance: 8 ohms
Power supply: 9V battery
Current drain: 14mA at no signal, 140mA max
Dimensions: 140mm W x 38mm H x 100mm D
Weight: 260g (including batteries) AP-1 Audio ProcessorThe AP-1 is the original Mizuho active audio filter from the 1970s, the precursor of the AP-1D. It matched the KX-1 antenna tuner and SX-59 preselector. Aside from size and shape the main functional difference between the AP-1 and AP-1D is that the older AP-1 has only one input compared to the dual inputs on the AP-1D.Receiver PreselectorsSX-3 Preselector

The SX-3 preselctor matches the KX-3 antenna coupler and AP-1D audio processor in appearance. It is designed for use with shortwave and AM broadcast receivers as well as inline with an amateur radio transceiver. Specifications:Frequency Range: 3-30MHz (in three bands: 3-7MHz, 7-14MHz, and 14-30MHz)
RF Gain: Over 15dB, continuously variable
RF Attenuator: -10dB
Input impedance: 50 ohms
Ouput impedance: 50 ohms (low) or 1 Kohm (high)
Maximum relay through power: 100W CW
Power requirements: 110/220/240VAC 50/60Hz
Dimensions 195mm W x 62mm H x 152mm D
Weight: 1.4kgSX-3 Manual (page 1) (PDF format).
SX-3 Manual (page 2) (PDF format).

SX-59 and SX-100 PreselectorsSX-59 preselectorDetailed information about older model Mizuho preselectors will be added here shortly.SX-59 Manual (PDF format).

SX-59 Schematic Diagram (PDF format). Frequency CountersDX-555D Digital Frequency CounterDX-555D Frequency CounterThe DX-555D is a 200MHz digital frequency counter. More information coming soon.