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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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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RF Milliwatt Meters
Type NDB-2 and NDB-3
National RF’s Type NDB-2 and NDB-3 RF Milliwatt Meters are affordable pieces of test equipment for both the RF laboratory and the home experimenter. Both provide a digital reading of RF power in dB reference 1 milliwatt of power into a 50 ohm load (i.e. 0 dBm). The circuitry consists of a low noise logarithmic amplifier that drives a digital A/D converting meter circuit. The lowest power levels that can be read are about –73 dBm (approximately 40 microvolts or .00000003 milliwatts). The maximum power input should not exceed 10 milliwatts (+10 dBm or .010 watts) when inputed without attenuation. An internal attenuator is provided and described in the next section.
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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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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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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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FREQUENCY DISPLAY UNIT
TYPE NFD-1
The National RF Type NFD-1 Frequency Display Unit was designed for use with vintage and classic communications equipment, to display the received or transmitted radio frequency. The unit incorporates an internal processor that allows the intermediate frequency (IF) to be counted out by the frequency counter. The resultant display is the actual frequency that the equipment is receiving or operating at.
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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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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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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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Analog Power Supply
Type NPS-2412
National RF's Type NPS-2412 analog power supply was designed to be used in communication equipment where radiated switching inverter noise from conventional “switching type” supplies is not acceptable. The power supply consists of a standard rectified transformer output driving a pair of voltage regulators and filtering networks. The 2412 offers an adjustable voltage output between 2 and 24 volts as well as a fixed voltage output of 12 volts. A maximum of 20 Watts of DC power can be supplied from the unit. As the voltage regulators dissipate power in the regulation process, the power to the load is derated accordingly, dependent on the set voltage to the load. The adjustable regulator is a standard LM-317T integrated circuit device. The fixed regulator is a standard LM 7812 device. Upon customer request, the LM 7812 device may be changed to any voltage rating within the the LM-78xx series of regulators. Contact National RF for this modification if desired.
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GEOPHYSICS, SEISMIC, and ATMOSPHERICS RESEARCH RECEIVER
Type RAS-1
Called the RAS-1, the receiver is designed for ultra low and very low frequency scientific research work, including the exploration of low frequency emissions due to seismic and earth-quake activity, study of atmospheric phenomenon such as "whistlers", and low frequency Sudden Ionospheric Disturbance (SID) and electromagnetics phenomenon. The RAS-1 will receive signals from under 200 Hz. To over 250 KHz in both narrow bandwidth modes as well as broad badnwidth reception.
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MOD MONITOR
TYPE HFX-1
The Type HFX-1 Modulation Monitor is an ancillary piece of equipment, which is used with narrow bandwidth, or older oscilloscopes to allow viewing of RF signals and particularly modulated signals as high as 55MHz. The equipment contains an RF signal source and a broadband mixing circuit which converts the high frequency signal to an intermediate frequency within the oscilloscope’s range. The frequency control dial is simply adjusted until the RF signal is viewed on the scope. BNC connectors are mounted on the rear panel to allow interconnect to the scope and RF probe. This product was previously called "oscilloscope frequency extender" and may be used to view other high frequency signals on older or narrow band scopes.
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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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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!
