• Tilt Super Antenna

As an HFpack Member, you can support HFpack by wearingan HFpack T-shirt or hat at hamfests or when operating portable. Showyour HF spirit! For members, there are HFpack bumper stickers, HFpackradiogear bags, and all the HFpack stuff you've seen HFpackers with in the field, athamfests, and club meetings.

These are now available online to HFpack members. Just aclick of your mouse at the Over 100 cool items, including clocks, mugs,field notebooks, camo/green stuff, accessory bags, buttons, stickers,mousepads, frequency list stickers, license plate frames, and many other things for your shack orportable operation. Great for gifts. Fast shipping.Other Portable HF SSB Radio Collector Articles:This article provides educational and reference information on theKachina MP-25 and Scientific Radio Systems SR-MP-25 HF SSB Manpack Transceiver. RADIO COLLECTORS INFORMATION.

NOT FOR SALE. FOR REFERENCE ONLY.Note: Kachina Communications, Inc.

Tilt Super Antenna

Made the MP-25. Kachina Communications, Inc. Closed its HF equipment business in May 2001.Under private label, Kachina Communications supplied SR-MP-25 toScientific Radio Systems, Inc. Which went out of business in Sept 1997.A typical MP-25 set sold new for approximately US$5000 toUS$8000, depending upon which accessories and options were in thepackage.The Kachina MP-25 is a manpack type transceiver which may beused for portable, pedestrian mobile, vehicle mobile, or fixedinstallations. The transceiver is designed to receive and transmit SSBsingle sideband suppressed carrier (2R7J3E), semi-break-in CW telegraphy(350A1A), and compatible amplitude modulation (2R7A3E) signals.

AM isreceived as USB.Frequency coverage is 2000.0 kHz to 14999.9 kHz in 0.1 kHz digital stepsusing front panel rotary switches. The MP-25 is designed to operate overthe temperature range -30C to +55C and is fully waterproof to 1 meter.The transceiver features an internal simplified manual antenna tunerwith a locking rotary whip antenna mount and standard 3/8'-24 threadedfittings. Antenna connections include push-on posts for random wireattachment and BNC connector for mobile or dipole antennas. The frontpanel has a waterproof speaker with on/off switch for monitoring. Acompanion 12V power supply / battery charger for base station operationalso provides an external speaker for clear crisp reception of voice.Operation and Maintenance Manual (Service Manual)Kachina MP-25SPONSOR ADVERTISEMENTMP-25 Standard Features. Digital frequency selection with tactile rotary switch knobs. Built-in antenna tuner for whip, random wire, or dipole.

Integral rechargeable battery pack (NiCd or SLA). Long term operation on battery due to low receive power consumption. SPONSOR ADVERTISEMENTAccessoriesThe following accessories were available from the factory:. MP-25-HS2 Handset a- H-189/GR miniature military handset. Fully Waterproof. Dynamic, 150 ohmimpedance.Weight.51 kg. MP-25-HG Hand Generator h- Designed to operate the MP-25 Transceiverand simultaneously charge the batteries.

Batteries must be in place whenoperating the generator. Weight 2.0 kg. MP-25-CB Carrying Bag e- Manufactured of nylon, the bag not onlyprotects the transceiver, but, also provides pockets for the variousaccessories such as the microphone, folded whip antenna and otherantenna accessories. Fitted with adjustable padded straps. Available inolive drab or green camouflage pattern. Weight 0.63 kg.

MP-25-AD Dipole Antenna c- This center fed dipole iswound on high impact plastic spools. A calibration chart is provided toshow turns to be removed from the spools. Final adjustment is made usingthe MP-25 built-in SWR bridge. Antenna is provided with 10 meters ofRG58-U coaxial cable.

The dipole antenna may also be used as a longwireantenna. One section of the antenna is used as a ground plane. Weight 1.3 kg. KC-SP-1 Solar Power Unit i-Allows transceiver batteries to be charged from the sun. Fitted withmeter so that the collector may be positioned for maximum charge Limitedavailability.

Weight 1.94 kg. MP-25-PSC Power Supply/Charger g- Powers the radio in base stationoperation or charges one battery pack, either sealed lead acid or nickelcadmium. A front panel switch converts the base station power supply toa battery charger allowing the battery to be charged while attached tothe transceiver. The supply allows operation from 110/220 volts, 50 or60 Hz. A fuse and current limiting cut-out protect the power supplyagainst short circuits. The supply is electronically regulated andcurrent limited, and the output is over voltage protected.

Containsbuilt-in loud speaker for improved audio during base station operationof MP-25 Transceiver. Weight 3.65 kg. MP-25-AW Folding Whip Antenna b-Made of fiberglass.

Collapsible and may be stored in carrying bag.Connects automatically when fitted to transceiver. Antenna may berotated to any angle with respect to the transceiver and locked inplace. Weight 0.39 kg. MP-25-MB Mobile Mounting Bracket f- Heavy duty type, clamps around body of transceiver, allowing a strong attachment to the vehicle. Weight 1.12 kg.

MP-25-MC Hand Microphone j- Military type M-80/U, rugged, dynamic typemicrophone. Used when transceiver is operated with the MP-25-PSC powersupply speaker in base station operation. Weight 0.39 kg.Kachina MP-25.

MP-25-BP(NCE) Nickel Cadmium Battery Pack d- Clips on the rear oftransceiver. If nickel cadmium batteries are not fully discharged theywill develop a memory for the lower charge. Unlike sealed lead acidbatteries, they should not be trickle charged. Their regulation issuperior to that of the lead acid types. MP-25-BP(LAE) Sealed Lead Acid Battery Pack d- Consists of two 6 amphour, 6 volt, rechargeable, sealed, lead acid batteries in protectivebox.

Clips on to rear of transceiver. Unlike nickel cadmium batteries,sealed lead acid batteries need not be deep discharged. Regulationinferior to nickel cadmium type. MP-25-CW Telegraph Key - May be positioned on senders knee or operated on a table or other surface. MP-25-HP1 Headphones - Military type H140/BU. Weight.69 kg. PN980014 Mobile D.C.

Power Cord - Allows the transceiver to be operated from a vehicle battery. MP-25-MW1 Mobile Whip Antenna - Stainless steel antenna approximately 2.5 meters long (9 Ft.). Weight 2.2 kg. MP-25-BL Ball Mount - For attaching the MP-25-A Wl Mobile Whip Antenna to the vehicle. MP-25-S2 Heavy Duty Spring - designed to be used with the MP-25-BL Ball Mount and the MP-25-A WlMobile Whip antenna. Helps prevent antenna damage. MP-25-CH Battery Charger g- Similar to MP-25-PSC(E) above but allowsthe simultaneous charging of 4 battery packs, either sealed lead acid ornickel cadmium.

The internal antenna tuner is capable oftuning and matching any HF antenna of any type encountered in the fieldor base station operations. In the Tune mode, the transmitter transmits alow power level CW carrier for tuning purposes.

The Antenna Tuner isadjusted using the Tune mode by tuning ④ ANT.TUNE lower knob (capacitor) and ⑤ANT.TUNE top rotary switch (inductor) for lowest reading on the meter,indicated by the green color. If SWR is in the red, check antenna ortuning.Kachina MP-25 SWR Tune Meter Color Code1.0 to 2.02.0 to 3.03.0 or higherNote: SWR levels are approximate. Procedure for Tuning a Whip or Random Wire Antenna1. Set the ④ ANT.TUNE lower knob to the 2 position.2. Set the ⑤ ANT.TUNE top rotary switch to the 22 position.3. Set the PORT/MOB switch to the PORT position.4. Switch to TUNE mode.5.

Rotate the ⑤ ANT.TUNE top rotary switch counter clockwise, stopping at the lowest reading on the SWR meter.6. Rotate the ④ ANT.TUNE lower knob, stopping at the lowest reading on the SWR meter.7. Repeat steps 4 and 5 above sequentially for lowest reading on the SWR meter.8. Return to USB mode. Bypass the Antenna TunerFor use with 50 ohm BNC external antenna such as resonant dipole or broadband dipole.1. Set the ④ ANT.TUNE lower knob fully counter-clockwise to the 0 position.2. Set the ⑤ ANT.TUNE top rotary switch to the 23 bottom vertical line position.3.

Set the PORT/MOB switch to the PORT position.(see photo at right)PORT./MOB. SwitchThe PORT/MOB switch should normally start in the PORT position for mostantennas. This includes 50 ohm antennas, dipoles, random wires, and themanpack whip antenna.

It may be put in the MOB position for tuningsome mobile antennas or fixed station antennas which are connected viathe DIPOLE connector (BNC) or it may be needed to achieve an acceptable green SWRwithsome other types of antennas at lower frequencies (2MHz to 8MHz). Inthe MOB position, an additional shunt capacitor of 750 pF is applied tothePI-network antenna tuner on the transmitter side, which is especiallyhelpful for tuning the lowest frequencies, but MOB position is usuallydetrimental to tuning at higherfrequencies (10MHz14MHz).For more information seeWhip Antenna MountThe rotating whip antenna mount on the right side of the faceplate issuitable for lightweight whip antennas in field portable operation. Whenusing a mobile or fixed antenna connected to the DIPOLE (BNC) connectoror the antenna push terminals, the whip antenna and its hardware shouldbe completely removed from the mount, to avoid RFI, noise problems, anddetuning of the intended external antenna system.Using Whip AntennasThe Kachina model MP-25-AW Folding Whip Antenna is a lightweightcollapsible fiberglass whip, originally supplied with the MP-25. Thestandard military manpack metal AT-271 collapsible whip was suppliedwith later versions, along with 3/8'-24 fittings which interlock withthe quick-disconnect fitting of the mount.

Care should be taken to avoidextreme angular shock or leverage on the whip mountwhile operating /Pedestrian Mobile with heavy or long whips such as theAT-271. After-market antennas with integral loading coils, such as theprovide greatly increased efficiency (+5dB or more) over the stockwhip, and are highly recommended for use with the MP-25. When operatingportable or /Pedestrian Mobile with any whip antenna, a single insulatedwire counterpoise should be attached to the push terminal groundconnection of the MP-25. The counterpoise wire may be a random length ormay be cut somewhat shorter than a quarter wavelength at the desiredoptimum frequency. In practice, 4 lengths of counterpoise wires havebeen found to be suitably optimum for the entire operating range of theMP-25, when most of the wire is deployed on the surface of earth groundsoil.Recommended MP-25 field counterpoise wire lengthFREQUENCY RANGELENGTH2MHz to 3.4MHz80ft (25m)3.5MHz to 5.9MHz45ft (14m)6MHz to 8.9MHz30ft (9m)9MHz to 14.9MHz10ft (3m)providesafter-market pre-tuned teflon wire portable counterpoise radial setswhich are suitable for MP-25 and other manpacks in the field. Image:Kachina MP-25 Antenna TunerSettings for 50 ohmexternal antennaAudio Connector Pinout Microphone, Speaker, Handset, Headset, CW KeyThe audio and accessories connector is a U-283 (the 6 pin version of thecommon 5 pin U183 military audio panel connector) and it is compatiblewith most 5 pin standard U-229 microphones, handsets, headsets,speakers, etc.

The MP-25 does not output microphone sidetone to the handset speaker audio.Modems, Devices, Repeaters, and +12V AccessoriesA variety of interconnect devices may be used to expand or interfacewith the transceiver. When setting up equipment, observe propercompatibility procedures, especially pin signals and voltage limits forgear using center pin features. The +12V pin is capable of deliveringseveral amperes, limited by the internal circuit breaker, dependent uponhow much total current is used for transmit. Image:Pin out of Kachina MP-25 front panelaudio connectors type U-283(compatible with U-229 or U-329 accessories)Compatible MicrophonesStandard military H-189 and H-250 handsets, and M-80 microphones are compatible withthe MP-25. The M-80 seems to have the most punch for excellent transmit audio.Many other types of standard military audio U-229accessories, such as intercoms, handsets, and headsets work well withthe MP-25. The microphone input circuit has an impedance ofapproximately 1k ohm, and is suitable for low impedance dynamicmicrophones and audio equipment in the range of 50 ohms to 1 k ohms (50,150, 600, 1k, etc). Both front panel audio connectors areidentically connected in parallel and may be usedsimultaneously.Photo: Typical MP-25 compatible handsets H-250, H189, and M-80 microphone using standard military U-229 connectorCW OperationA manual CW key may be attached, connected from pin E to pin A of theU-229 (or U-329) connector.

The CW frequency is offset +800Hz (0.8kHz)above thedisplay frequency. In CW mode, the radio operates Upper Sideband, and issuitable for crossmode operation with stations using Upper Sideband(USB) voice. To zero beat with another CW station, align the displayfrequency to match the received tone of the CW sidetone pitch.

In otherwords, when the other station's CW signal sounds like it is at the samepitch as the MP-25 CW sidetone, it is the correct zero beat frequency.Thereis no special narrow CW filter, it uses the standard USB 2.7 kHz filter.The logic level HI of the CW pin is +12V, and ground to send. If using abug key or an external electronic keyer, be advised that theCW circuitry is rated at 35 WPM morse code maximum, and the transmitteddits may be clipped if that speed is exceeded. The default keying issemi-break-in, which has a fairly fast fixed time delay. It is normal toencounter some chirp on the transmitted CW when using semi-break-in ateach initial key-down pulse interval.

To reduce the chirp, hold down themicrophone PTT while sending a CW transmission. Microphone audio ismuted from the transmitter when mode switch is in the CW position. CW transmit frequency is offset 0.8kHz above display frequency.Examples of Kachina MP-25 display frequency to CW zero beat conversion for common ham radio andSET DISPLAY FREQUENCYkHzACTUAL CW TRANSMIT FREQUENCYkHz3558.1.8.9.16.758.242.514343.3Photo: Typical CW key with U-229connectorExternal ModemA computer sound device or external modem with audio and PTT interfacemay be attached to the front panel connectors. When transmitting with amodem, the BAT.READ/LOW PWR switch should be placed in the LOW PWRposition, to avoid overheating due to continuous duty power output. Thefollowing diagramshows connection of a computer sound device modem to computer earphoneoutput, microphone input, and a simple PTT interface to a serial portmade with atransistor and 2 resistors.

Most standard computer-radio interfaces maybe wired similarly. The normal logic level of the PTT pin is +12V, andground 0V to transmit. It is suitable to be driven by either opencollector or relay closure. It is not suitable for direct 5V, 3V, or1.8V logic connection (use an open collector buffer instead).Image: Connection schematic diagram of U-229 female cable connector for computer sound device modemExternal Speaker and Power Supply / ChargerThe power supply and charger MP-25-PSC (first version) or MP-25-CH(second version) has a good sounding external speaker in it.

It is alinear supply providing OPERATION for the transceiver and CHARGE for thebattery. The power supply plugs into the front panel J903 connector, and provides +12VDC nominal from selectable 115VAC or 220 VAC mains.It is recommended that the battery be eitherremoved from the radio while charging, or else all the panel clamps beloosened, to prevent volatile gas (hydrogen / oxygen) build-up inside the sealed radioenclosure.

The power supply OPERATE/CHARGE switch must never be in theOPERATE position while the battery is connected in the radio. The battery may be charged while installed in the radio. Charging Battery Reminder: always loosen the 6clamps of the manpack case cover while charging, and slightly let thecover separate from the front panel gasket, to release the hydrogen andoxygen gas.

TheOPERATE/CHARGE switch must only be set to CHARGE while the battery is installed andattached in the radio. There is a separate charge cable which may beplugged into the battery for charging it externally while the radio isoperated. For the NiCad battery, the charger power should be turned off when the battery is fully charged (about 13.8 to 14.0 VDC).Keep in mind that the front panel volt meter is intended only for arough check of battery voltage. The front panel meter is not accuratelycalibrated enough to determine full charge voltage. So, a separatecalibrated voltmeter should be attached to Pin F of the audio connectorto test the voltage, and determine meter error so that it can better beutilized as a charge indicator.The SPEAKER/ON switch on the front panel of the transceivercontrols both the internal speaker and the power supply speaker, it doesnot mute the receive audio ported through the front panel audioconnectors. Kachina MP-25Note: This article is for educational and reference purposes only. No warranty or guarantee of the information is offered.HFpack isthe International Resourcefor Amateur Radio HFPortable - Mobile - Emergency Communications - Ham Radio InformationExchange - Nets- Ionospheric Propagation.HFpack is an international news organization.HFpack provides aninformationexchange about transceivers, antennas, systems, High Frequencycommunications, QRP, HF packs, propagation, EMCOMM, new developmentsandtechniques in VHF and HF portableoperation.

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