FRG - 100

Manufactured by Yaesu Musen Company Ltd., Tokyo.

Following the introduction of the fully microprocessor-controlled FRG-8800 in 1985, which featured various memory and clock functions as well as the possibility of direct frequency input, Yaesu launched the FRG-100 as a small tabletop receiver in 1994, which was soon very popular among listeners due to its size and uncomplicated operation scheme. After Yaesu subsequently stopped building shortwave receivers, the FRG - 100 became the last of a successful receiver series.

Yaesu FRG-100

Technical data

Power supply


  • 238 x 93 x 243 mm, weight 3 kg



Compared to other tabletop receivers, the FRG-100 is extremely compact, measuring 23.8 x 9.3 x 24.3 cm and weighing 3 kg, it is on a par with the NRD-345 - or AOR-7030 receiver. It is also obvious that the power supply unit is not integrated in the set, but is located halfway between the mains socket and the set, as found in notebook computers, thus saving space in the cabinet and shielding measures between the power supply unit and the highly sensitive HF components. The cabinet is anthracite - dark grey. When switched on, the S-meter and frequency display are backlit in orange-yellow. A small loudspeaker is built into the cabinet and radiates upwards.

The front panel appears quite tidy in the design of the nineties, the receiver shows a very nice design, especially when illuminated. Numerous small buttons are located next to each other and have not only double-assigned functions, but also have other functions when pressed when the receiver is powered up. A plastic leaflet that can be pulled out from the bottom of the receiver provides information about the timer, scan and programming functions. One major drawback becomes clear at first sight: the set has no numbered keypad, this was a victim to the compact size.

In the bottom row of controls, the headphone jack is located on the left, below the main switch (the power supply must be unplugged to avoid the receiver being in standby mode all the time). Three rotary controls are used to select one of the fifty memory locations, to adjust the squelch setting and act as volume control. Four push-buttons activate the operation modes; when pressed repeatedly, the SSB button switches between the upper and lower sideband and the AM button between the wide and narrow IF filters. The impulses of the tuning knob, which comes with a flat finger recess, are taken over by an optoelectronic coder. As with other modern tabletop receivers, there is no mechanic tuning mechanism in the Yaesu FRG - 100 anymore; the frequency is processed by a microprocessor via a PLL synthesis circuit.

The Fast key increases the tuning step, depending on the Operation mode, from 100 Hz to 1 kHz for AM reception and from 10 to 100 Hz for SSB reception. The up/down keys are used for fast frequency changes; when the fast key is pressed, the frequency in AM reception is increased by 1 MHz at the touch of a key. The small keys at the top right are used for scanning.

In the middle row of keys to the left of the tuning knob, 14 small keys control all operating modes. The keys on the far left attenuate the input signal by 6 or 12 dB, pressed together the value is added; a separate RF gain control is not provided.

The next buttons are required for VFO memory mode operations. Due to the receiver concept of the FRG-100, the currently received frequency is stored in the so-called VFO, the variable frequency oscillator. Stored frequencies are read from the memory location into the VFO location, frequencies to be stored are saved from the VFO into a memory slot.

In amateur radios, the VFO was used to set the frequency with the main tuning knob, in contrast to fixed frequencies, which were set by frequency crystals. Some receivers work with one VFO and a large number of memory locations, some with two VFOs A and B in addition to the memory locations. As a rule, the VFO frequency can be easily accessed directly, i.e. it corresponds to the currently active memory frequency from which the set can be tuned to another frequency. In the age of microprocessor-controlled receivers, the VFO term is still a relic without technical meaning.

The keys located underneath activate the clock and timer mode, the SELect and SET keys allow access to programmable functions, so that the IF filters and tuning step widths used by default when changing the operation mode can be reprogrammed. As a special feature, the key combination SET + MEM CLR can be used to adjust the BFO frequency offset (e.g. for operation with an RTTY decoder); during SSB reception of a sideband of an AM station, this allows the position of the BFO/auxiliary carrier or the IF filter passband curve to be shifted in relation to the auxiliary carrier, similar to passband tuning.

With the key combination SET + SEL, any available IF filter can be activated in any operation mode. By pressing the key when the receiver is turned on, factory-programmed basic settings of the set can be accessed and these settings can be changed as required. For example, you can get rid of the annoying confirmation beep after each keystroke or you can retune the PLL main oscillator with the aid of an external frequency standard. To do this, as well as to make full use of all the memory and scan functions, it is necessary to study the extensive operating manual, as is usual with Yaesu.

On the back of the receiver are the loudspeaker, tape and muting connections, the sockets for the coaxial low-impedance and high-impedance long-wire antennas and the CAT socket in form of a round DIN socket for external computer control.

With a control cable and appropriate software, the FRG-100 can be programmed with all memory, scan and timer functions. The external frequency keyboard offered by a third-party manufacturer (BEEI), which is an indispensable accessory for regular use, can also be plugged into this socket. The corresponding control commands are fully documented in the manual.

As a very compact tabletop receiver, the FRG - 100 meets the basic requirements of a shortwave receiver suitable for DXing. The input sensitivity is high, due to the electronic preselection and the high first intermediate frequency, the FRG - 100 has a very good large-signal behaviour. Yaesu's experience in amateur radio, where signals with very different levels have to be processed, has contributed to the success of the receiver.

In the first version presented, the AM IF filters were too wide and had insufficient skirt factors, subsequently the filters were replaced so that the receiver is DX capable even without filter modification - this second version was marketed in the USA as FRG-100B.

FRG-100 first version / FRG - 100A

  • CFJ455K15 (2.7 KHz, Murata), CFW455I (4-5 kHz, Murata), CFW455H (6 kHz, Murata)

FRG-100 later version / FRG - 100B

  • CFJ455K15 (2.7 KHz, Murata), LF-H2S 3Y (NTKK), LF-H6S 37 (NTKK), opt. FM LF-H15S (15 kHz FM, NTKK)

A small drawback, which is important for broadcast station listeners, is the lack of a numeric keypad for direct frequency input of. You could investment in an external calculator-like keypad, but this is only very rarely found with second hand receivers nowadays.

Technical principle

The radio frequency signal first has to pass through the 6 and 12 dB attenuator stages and reaches the electronical preselector via a low-pass filter. In the first mixer, the signal is converted to the first IF of 47.21 MHz and passes through a crystal filter. After the second mixer, in which the signal is converted to the commonly used IF of 455 kHz, and the noise blanker, the signal passes through the IF filter bank. At this point, the optional CW filter with a width of 500 Hz or another optional filter can be installed. After further amplification, the signal is fed to the AM and SSB demodulator stage, and the final audio signal is sent to the loudspeaker.


The set is solid state.

Technical documentation


Further information

en/frg-100.txt · Zuletzt geändert: 2022/12/25 18:34 von mb