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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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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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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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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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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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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Reference Antennas
Type NRD
Reference antennas are precision dipole antennas that offer a fixed 2.15 dB of gain over an isotropic antenna along the major lobe axis at specified frequencies (2.15 dBi). They are intended to be used for antenna field pattern and gain measurements, or general RF sensing in the laboratory.
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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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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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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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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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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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Mini Receiver
FB7-NX
In about 1935, the National Radio Company of Malden, Mass., brought out a “hot” high frequency receiver, called the FB7, and the subsequent FB-7X. It featured a super-hetrodyne design with plug-in coils that gave it a broad frequency range. The “X” model also incorporated a crystal filter in the intermediate frequency section, thus giving it additional selectivity. The receiver was viewed by radio amateurs as a technological breakthrough, and it was also used commercially for point to point high frequency communications. As the receiver did not have an internal RF amplifier section, a separately tunable RF amplifier was later provided in a separate enclosure for additional performance capabilities. Now, National RF, Inc., is resurrecting the fabled receiver name with an all solid-state, hot mini receiver, which also utilizes plug-in coils to cover the HF spectrum. The mini-receiver is designed for use by radio amateurs as well as serious short-wave listeners, and allows reception of AM, CW, and SSB signals. It incorporates a super-hetrodyne design with a dual gate FET built-in RF preamplifier and a ceramic filter for selectivity, often required when used in a crowded amateur radio band. In addition, the receiver has a buffered rear panel output of the high frequency oscillator for use with either a frequency counter for exact receive frequency display, or for interface with an outboard transmitter. A rear panel jack is also provided for muting the receiver when a transmitter is placed into the transmit mode. And, the receiver is small enough to fit into carry-on luggage and taken on trips when it is desired to “keep an ear” on amateur radio or other high frequency activity. The receiver utilizes rear panel plug-in coil assemblies which contain the RF amplifier, mixer, and oscillator tuned circuits. Each plug-in coil assembly also comes with a separate dial scale, which is inserted onto the front panel for displaying the tuned frequency. A very smooth 6 to 1 planetary drive is used for tuning the receiver. Other front panel controls include RF preamplifier peak, volume control, Beat Frequency Oscillator adjustment, and RF gain control. Other switches include filter bandwidth, AM/CW/SSB selection, Power, and a general coverage/band spread control for certain plug-in assemblies. The receiver is intended to drive head-phones via a rear panel jack, but has sufficient output to drive a small external speaker.
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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.
