National RF, Inc
National RF Inc offers State of the Art Radio Frequency and Unique Electronic Devices
- 858-565-1319
- 858-571-5909
- 7969 Engineer Road
Ste. 102
San Diego, CA 92111
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Spectrum Marker Generator
NSG-2
National RF, Inc. is pleased to announce the production of a new device, the Type NSG-2 Spectrum Marker Generator. The generator is intended to be used with either spectrum analyzers or communications receivers to mark specific frequency intervals in the RF spectrum. When used with receivers, it is essentially a frequency calibrator, thus making it attractive for use with vintage receivers with analog dials. The NSG-2 provides a leveled amplitude output over nearly 100 MHz of RF spectrum, thus making it ideal to mark frequencies and signal levels on spectrum analyzers. In addition, it may be used with a spectrum analyzer, in lieu of a sweeping type generator, to align lowpass, highpass, and bandpass filters with passbands greater than 20 KHz.
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TURBO-TENNA 137 MHz Weather Satellite Antennas
WX-137 SERIES
The WX-137 series of antennas are marine-grade 137 MHz circularly polarized antennas designed to receive weather satellite images from the polar orbiting NOAA and Meteor satellites. Manufactured from stainless steel and ABS plastics, the assemblies are sealed and designed to survive marine service, although they may be used on land as well. Each antenna is available with or without a gasfet preamplifier which provides about 16 dB of gain and is physically located adjacent to the antenna.
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Low Frequency Active Antenna And Amplifier
Type NLF-2
A Hot, Active, Noise Reducing Antenna System that will sit on your desk and copy 2200, 1700, and 600 through 160 Meter Experimental and Amateur Radio Signals!
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Receiver Semi-Kit
75-NS-3
National RF’s 75-NS-3 receiver is a complete super-hetrodyne mini high frequency receiver, designed specifically for the short-wave listener, electronics enthusiast or radio amateur, who wants to use their hands and build a radio. The receiver is offered as a semi-kit in which the electronic assembly is loaded and functionally tested at the National RF facility. The customer must then go to the grocery store (yes…the grocery store!), procure a can of lunch meat, eat it or give it to the dog, and then proceed to drill and paint the can, in order for it to become the receiver’s enclosure! As the name of the preferred potted meat can has a registered trademark by Hormel Foods, Inc., it won’t be mentioned on this web-site. However, the name of the product is synonymous with unwanted email!!! In addition, there are other food products that might be found that are packaged in the same metallic enclosure. Detailed drilling instructions and final assembly instructions are provided as part of the kit. All other parts required for completion of the receiver are provided as well. Recognizing that the finished assembly looked somewhat like the fabled Collins receiver of the ‘60s, the 75S-3, (particularly when the can is painted a light gray) National RF engineers dubbed it (with tongue firmly planted in cheek, of course) the 75-NS-3! Although we have had fun packaging this receiver in a lunch meat can, it is nothing to turn your nose at! Its performance and portability will surprise you, and it is an ideal radio to bring with you on any trip!
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VECTOR-GUN HANDHELD DIRECTION FINDING ANTENNA SYSTEM
HFDF
National RF's Type HFDF active directional antenna system consists of a high gain RF amplifier coupled to a tunable Faraday shielded loop antenna. Several loop antenna assemblies are available to provide coverage of frequencies in the HF and low VHF spectrum. Due to the nature of a Faraday shielded loop, the antenna exhibits a sharp null through the diametric center of the loop. This null is used to determine the direction of incoming radio signals or to locate electrical noise being radiated from some source. The internal high gain amplifier is used to compensate for the inherent inefficiency of the actual loop at the operating frequency. Overall, the system dynamic response is about +6 dB as compared to the dynamic response of a dipole. To aid in the direction finding process on strong signals, an internal 30 DB attenuator is provided. As the loop antenna presents a bi-directional response, tri-angulation may be required to eliminate the ambiguous signal direction. The line of site of the incoming signal is determined by listening for a signal null on the receiver or by watching the receiver’s S-meter.
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Portaquad
Type 2-MQ
The Type 2-MQ Portaquad is a high-gain, full size 2-meter quad antenna designed for portable operations. The mechanical design allows it to fold for stowage or transportation in a container. The container also acts as the antenna’s support base when the antenna is erected. After familiarity with the device is achieved, the antenna may be erected or collapsed in approximately one minute.
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Noise Location Package
Type HFDF
National RF’s Type HFDF high frequency location system is a proven noise hunting and location directional antenna system that allows you, in many cases, to walk right up to the source of High Frequency (HF) noise! Used by several power companies around the United States, professional noise hunters, and other communications specialists, the HFDF has located noise sources that emanated from pole power transformers, arcing electric fences, CATV in-line amplifiers, plasma TV screens, and even Marijuana grower’s heating lamps! The system incorporates several plug-in, tunable magnetic loop sensors of a proprietary National RF design, that cover the frequency range between 1.8 MHz and 55 MHz. The unit is packaged in a hand-held, lightweight metallic enclosure, with a pistol grip and a magnetic compass mounted on top. The compass is used to get magnetic bearings to the noise source, which may be plotted on a map to triangulate, and ultimately pin-point, the location of the noise source. In certain cases, our customers tell us that they have been able to walk right up to the interfering noise source and correct the situation on the spot!
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RF Proximity Detector
Type RPD-2 AND Type RPD-2A
The Type RPD-2 Radio Frequency (RF) Proximity Detector is designed to detect and locate devices that radiate radio waves in the high frequency to low microwave frequency range. Such devices often include surveillance and “spy” equipment. The Type RPD-2, when used with the different sensors, will detect the emanation of the radio wave within a confined area, and then isolate its location to within approximately a square foot. The type RPD-2A may be used as an RF field strength indicator for antenna field strength measurements. The RPD-2A is identical in function except that the meter scale is calibrated in relative dB units.
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Attenuators
The National RF line of attenuators are compact, affordable attenuators which are ideal for insertion between a direction finding antenna and a receiver/transceiver, to aid in the DF process. In addition, they may be used in the laboratory for a low-power, in-line attenuation purposes. The affordable price is achieved by utilizing standard 5% tolerance resistors and commercial hardware. For laboratory purposes, an attenuation versus frequency curve (to 500mMHz) is provided.
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VHF/UHF Handheld Signal Location Antennas
Type NVF-2
The Type NVF-2 series of handheld directional antennas are used to locate interfering signals or noise in either the 420 – 470 MHz (Type NVF-2A) or the 900 MHz ISM band or cellular telephone bands (Type NVF-2B). Both models incorporate a solid reflector positioned behind a resonated half wave driven element, both elements being mounted on a fiberglass rod with an integral pistol grip. The configuration of the reflector and driven element are such that a deep null in the signal being received will occur when the antenna is pointed in the direction of the signal being radiated. A T-pad resistive attenuator is also incorporated in the antenna mounting enclosure to aid in the direction finding process on very strong signals or when excessive reflections present multiple returns.
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Precision Dials
HROII-PD and HROII-PDA
National RF’s HROII-PD and PDA precision dials were inspired by the earlier National Radio Company’s famous HRO series of communications receivers. This earlier equipment incorporated a ten turn dial with a rotating number plate on the inside. Every 72 degrees of rotation, a new number appears in a rectangular cutout in the dial skirt. The numbers count from 0 to 500 in decade intervals. The HROII-PD and PDA duplicate this counting action but in a smaller diameter assembly than the earlier dial.
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Vector Finders with InternalAttenuators
VF-145 LA AND VF-145 LMA
The VF-145 LA and LMA models are functionally the same as the VF-145 L and LM on both electrical performance and mechanical specifications. However, the LA and LMA models include an internal PIN diode attenuator that provides up to 12 dB of attenuation (measured at 150 MHz, attenuation decrease slightly as operating frequency increases) to the incoming radio signal. This attenuation occurs after the signal is received by the unit and phase shifted for processing, but before it is placed on the coax feedline to the receiver. In addition, the PIN diode utilized will absorb short burst of RF should transceivers be keyed accidentally by the user. This feature aids in very strong signal DF operations but will not totally guarantee against system overload under very strong RF emissions.
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VHF Radio Direction Finding Antennas
Vector-Finder Series
The Vector-Finder Series of VHF direction finding antennas provide a compact, lightweight, active antenna, suitable for use in the field with handheld transceivers and scanning radios. The mechanical design allows the sense antennas to be folded back to provide a compact unit, easily stowed or transported in any vehicle. The system interfaces with any FM receiver or transceiver via the antenna jack and the earphone jack. Several different models are available to suit your pocketbook or unique field application, all of which operate on the phase shift technique. The VF-142Q models incorporate left-right indicators as well as an audible response from which the user can determine the true direction of the radio signal. The other types utilize the audible response generated by the equipment and heard on the user’s receiver or transceiver. All models operate from a 9-volt battery.
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POWER ATTENUATORS
TYPE ATF
National RF’s Type ATF Power Attenuators were designed to allow interfacing of linear power amplifiers to RF exciters, where a specific amount of drive to the amplifier is prescribed. Often, however, drive from the RF exciter exceeds this minimum prescribed level and some form of power attenuation must be used in order to not damage the input of the power amplifier. National RF’s type ATF-3 offers 3 dB of power attenuation (1/2 of the power) when used between the exciter and the amplifier and will handle an input power of 132 Watts, RMS (continuous power) while providing about 66 Watts RMS output power, when it is terminated into 50 ohms. In practice, the ATF-3 attenuator will handle exciters achieving Peak Envelope Power levels (PEP) in the area of 200 to 250 Watts while providing half of that power to the load. For less attenuation requirements, the ATF-1 and ATF-2 offer 1 and 2 dB of attenuation, respectively.
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ELT STALKER Vector-finder
VF-121
The Vector-Finder Types VF-121 and VF 121A are unique in the Vector-finder series of direction finding antennas. They incorporate a proven design, electro statically shielded loop sensing element with modern solid state low noise analog and digital technology to allow detection and location of aircraft band signals. Both the VF-121 and the VF 121A incorporate a unique digital modulator which allows the user to more easily home-in on unmodulated carriers. Such cases occur at airports when transmitter may be accidentally keyed on during aircraft overnight layovers. The VF-121 is specifically designed to be used on airport premises where signal strengths are high. To compensate for very strong signals, an integral attenuator is also incorporated to allow the user to operate the unit close-in to aircraft. The VF-121A differs in that a high gain, low-noise preamplifier is utilized with the sensing element in order to hunt signals that may be weak or at a distance. The unit is ideally suited for the location of ELT transmitters in the field. Both units are tunable over the 118 MHz to 130 MHz aircraft frequencies and interface directly to the user’s aircraft band receiver or transceiver via the antenna jack. With the antenna system connected to the receiver, the user will hear the desired signal. If the signal is unmodulated, the digital modulator will generate a tone on the carrier. When the handheld unit is rotated about, an audible null on the received signal or the generated tone will be heard. This null aligns with the axis of the equipment case and represents the direction of the received signal. This direction may be read from the black dial compass mounted on the top of the enclosure. As the response is bi-directional, triangulation may be used to determine the true bearing when the true direction is not known.
