Receiver Review: Yaesu FRG-100

FRG-100

Year Introduced: 1992
Power: Mains, 12VDC
Size: 238 x 93 x 243 mm
Weight: 3 Kg
Price: US$550, CAN$1000, ú1000
Coverage: 50 kHz - 30 MHz (USB, LSB, CW, AM. FM optional)

Value Rating star starstarstarstar

 


This review was compiled independently. The Medium Wave Circle and Radio Netherlands has no financial connection with Watkins Johnson, the manufacturer of this receiver.


 

Introduction

The FRG-100 a neat compact budget-priced receiver, equally suited for use in portable situations (listening expeditions) as well as at home in the shack. It was launched in Japan in August 1992, and started appearing in Europe and North America in early 1993. The set measures 238 by 93 by 243 mm and weighs around 3 Kg, but note that there is no built-in power supply for the radio. The radio comes complete with a AC mains power adapter, although it can also be operated from a car battery (it takes around 1100 mA at a comfortable listening volume).

Coverage of this receiver starts at 50 kHz and goes continuously up to 30,000 kHz. The radio can receives signals in four modes as standard AM, LSB, USB, and CW. An option exists for narrow-band FM.

 

Front panel

At first glance, the front panel of the FRG-100 is deceptively simple. The manual tuning knob dominates the right hand side of the panel. An analogue signal strength meter and LCD frequency/mode/memory/time display are arranged along the top. Two rows of mode and select buttons are placed in the middle of the panel. Volume, squelch and memory channel controls are of the conventional rotary kind. However, by pressing certain buttons before switching the radio on it is possible to change a lot of default settings. Some of these are cosmetic (whether the clock shows 12 or 24 hr display). But other defaults which control the scanning or the sorting of the 52 channel memory are useful additions to the receiver's functionality.

By pressing and holding the SET button and then selecting other buttons on the front panel you can customise tuning steps, change the beat note on CW between 400 and 700 Hz and select which of the bandwidth filters will be a default when each mode is selected. Fine tuning of the first local oscillator is also possible which is useful if you want to check the receiver's calibration against a know frequency standard such as WWV on 15 MHz. If you find that when you try to listen to AM stations in the SSB mode (so-called ECSS) and find that the receiver never exactly beats when the display shows the exact published frequency, this adjustment may also be useful. The radio displays by how much the local oscillator has been adjusted. Having set the offset the receiver stores this information. There is a danger that if you forget about this you may conclude that the receiver is permanently off-frequency.

 

Direct frequency tuning

The FRG-100 uses a combination of UP-DOWN keys and the manual rotatory tuning knob to tune the radio. There is no direct entry keypad, although the radio does have a connection on the back of the receiver for computer control (Yaesu calls it Computer Aided Tuning or CAT). It seems strange that Yaesu hasn't though of an optional keypad like the British company of Lowe did with their receivers since the UP-DOWN buttons is not as fast as a keypad. That's especially noticeable when you hear an unknown signal say on 5955 kHz and what to check whether is carrying the same programme as a known station on 21455 kHz. A metal stand folds out from underneath the radio to put the front panel off the table and operate the receiver panel at a slight angle. That makes operation much easier.

The radio does not have synchronous detection, so if you are listening to a broadcast station there is no way the receiver will lock on to the carrier frequency. However the receiver is remarkably stable and listening to AM stations in either LSB and USB will allow you to escape annoying heterodynes. The fact that the receiver tunes in 10 Hz steps in the SSB mode means that music is listenable in the SSB mode when properly tuned in. After 10 minutes of listening the pitch of the music was still acceptable. There is an optional crystal that can be installed to improve the receiver's stability. In practice this option isn't needed for broadcast listening.

 

Memory channels

The radio has can store up to 50 memories, storing the frequency and the mode of each. Storing frequencies is easy, and there is a useful feature which allows you to re-sort the stored frequencies into ascending order. You can review the contents of each memory channel by turning the memory control knob. If the memories are only partially filled review of only the active channels is also possible. The memories are fully tuneable. This means that if you have stored 15070 in the memory and select it, you can then start tuning up or down from that frequency. We found this was a useful quick-tuning feature for jumping between broadcast bands by storing a marker frequency in the memory system. An additional two channels in the memory are used for marking purposes.

Scanning of the stored frequencies is versatile. You can use the scan function to keep watch on a particularly frequency. The radio checks the chosen channel for activity every 5 seconds. You can be tuning another part of the dial while still keeping an ear out for any activity. The FRG-100 allows you to scan all the 50 channels. Or it is possible to group memories into 5 groups of 10, each memory then being given an alpha-numeric indication. Several types of scans are possible if you decide to divide the memory into 5 groups of 10 channels each.

Yaesu has been particularly keen to provide the user with a number of options to select things like the BFO offset. The manual explains this in detail assuming you are sitting in front of the receiver. Some of the detail may be confusing for the first-time user and Yaesu may have been better off writing a "Short-Cut Guide" for those owners who just want to get started without changing all the defaults on the first day. For some specialist listeners the fact that you can decide to always select the 4 kHz filter instead of the wider 6 kHz filter when AM is selected is a useful feature, especially since the 6 kHz filter is too wide.

The receiver has two built-in clocks, so one can be set to local time the other to UTC. The clocks are independent of each other, so the difference between UTC and local time does not have to be a full hour. A timer function is available although this only switches the radio on and off at a chosen time. It is not as sophisticated as the timer on the Sony ICF-SW77 which allows you to switch the radio on to a chosen frequency in the memory. You can enhance the receiver's flexibility by using computer control.

 

Sensitivity

Examination of the sensitivity shows that the FRG-100 is rather insensitive at the low end of its coverage range. Sensitivity on medium-wave is deliberately attenuated to prevent strong local medium-wave station overloading the sensitive input circuitry. The figures for short-wave show the set is extremely sensitive... in our opinion it is too sensitive in the region 1.8-17 MHz. Above 17 MHz there is not so much atmospheric noise. But connect a reasonable antenna to the FRG-100 and you find the level of atmospheric noise is around 3-4 microVolts.

Making the receiver so sensitive brings the overload threshold down as well. For many years we have been trying to destroy the common belief among short-wave listeners that "the more sensitive the set, the more stations it can pick up". If the front end circuitry is so sensitive that intermodulation products become a problem, you will improve the intelligibility of weak signals by switching in a signal attenuator (the FRG-100 has three possible settings, plus the off position) and turning up the volume control!

Sensitivity values for 10 dB s+n/n, measured at 60% modulation depth

Freq Range (MHz) Freq Range (MHz) AM-wide SSB/CW wide CW narrow
0.131 2.58 2.30 0.51 0.44
0.200 1.28 1.20 0.23 0.18
0.300 1.00 0.80 0.20 0.17
0.490 0.73 0.65 0.16 0.06
0.5-1.8 2.75 2.60 - -
1.8-17 0.73 0.65 0.17 0.10
17-30 0.52 0.50 0.17 0.10

A signal is only really intelligible when the (signal + noise) to noise ratio is 20 dB. We examined this using a signal generator modulated at 60% to simulate the sort of signals that shortwave broadcast stations put out (especially with audio processing units like Optimod-HF in use at many transmitter sites). At 10.1 MHz we got the following readings.

Signal needed for 20 dB s+n/n, 10.1 MHz, @ 60% modulation

Filter Signal in microVolts dBm
AM wide 3.23 -96.8
AM narrow 3.05 -97.3
SSB/CW wide 0.68 -110.4

 

 

Automatic gain control

The automatic gain control design on the FRG-100 is excellent, although there doesn't seem a way to disable it altogether. Listening to SSB signals it is often more pleasant to switch off the AGC and wind the RF gain control back to avoid distortion. The FRG-100 is such that any intelligible signal is adjusted to give the same audio level output.

RF in 50 Ohm (ÁV) Audio level (dB) s/n ratio (dB)
0.44 -6 6
0.59 -3 9
1.25 -0.5 -
28 -1 15
>28 0 -

 

S meter

The S meter is fairly accurate. Under 1 ÁV (S2) the meter gives an indication that is too low. Above 1.6ÁV (S4) the meter reads exactly one "S" point too much. The range of the meter is good and for a radio in this price category does a useful job as a tuning indicator. It is linear over a large part of the range.

 

Squelch

The squelch is useful when you're waiting for a signal to appear and want to silence the background noise until that signal comes on the air. The function is essential on scanners, less so on short-wave radios. The squelch range on the FRG-100 is disappointing. The rotary control moves one complete circle, starting at the "6 o'clock" position. In the range between 1/2 and 3/4 shut the squelch level rises from 2 ÁV to 9000 ÁV signal input. The control is so coarse that setting it accurately becomes impossible. The squelch is designed to compensate for fading. It switches in at a signal level of 2 ÁV when set to the "12 o'clock position" and switches out again when the signal drops to 0.6 ÁV.

 

Audio quality

There is no way to reduce the bass response on the output to either loudspeaker or headphones. In some cases the bass response can overload a pair of hi-fi headphones. The internal speaker is OK since it has a low bass response anyway. The optional Yaesu communications speaker does a better job than the built-in speaker.

The audio amplifier delivers 1.8 watt maximum with 10% distortion. At normal listening levels (100 mW output into 8 ohms at 1 kHz) the distortion on the AM wide position was measured at 5%. That's acceptable, although the distortion on SSB and CW is just 0.3%. That means that distortion on AM is as a result of shortcomings in the detector stage rather than the audio amplifier. However this is to be expected in a receiver of the price range. Overall the audio is rated at fair/good. Intelligibility is not affected by the audio distortion.

 

Dynamic selectivity / RF protection ratio

Manufacturers often quote their selectivity figures based on measurements of the filters before they are installed in the receiver. However it is possible that in the compact design of many communications receivers that signals can "leak" around the filters in such a way that the selectivity is reduced. There is therefore an internationally accepted way to measure the dynamic selectivity (adopted by the European PTT organisations to measure maritime receivers). We use the so-called CEPT method for all the selectivity measurements. This method also ensures that the effects of the synthesiser are also brought into the discussion. The procedure is simple. The FRG-100 is tuned to receive a weak signal which is just understandable, i.e. 20 dB s+n/n.

A second modulated signal is applied to the receiver's input at a number of frequencies close to the original signal and a note is made of how strong this interfering signal has to be before the original signal is moderately disturbed (i.e. 14 dB).

If you are listening to a station on the FRG-100 using the AM wide filter, an adjacent station 5 kHz away with the same signal strength will cause very annoying interference problems. The narrower AM filter is a bit better, but not by much. In practice the AM narrow filter is the best for listening to weaker broadcast stations. The maximum rejection of the AM filters is around 50 dB indicates the limitations of the IF amplifier design. More expensive receivers are able to achieve 60-70 dB rejection. But for a receiver in this price class the results are only acceptable. Lowe Electronics in the UK offers a modification using KIWA filters, the FRG-100DX.

 

Attenuator

In Europe we found that the attenuator on the FRG-100 was not a luxury. It has three positions marked 6, 12, and 18 dB. In practice we measured these as 5, 10.4 and 15.4 dB. Nothing wrong there! For listening in Europe we suggest that on the short-wave range between 1.8-17 MHz that the 18 dB position is used, the 12 dB is the best above 17 MHz. The 6 dB attenuator is best when listening to medium-wave since the sensitivity is deliberately down on this section of the dial anyway.

 

Conclusions

Yaesu say the aim was to produce a better shortwave listeners receiver for about two-third of the price of the old FRG-8800. They have succeeded very well. For the broadcast listener, the FRG-100 is better than the Lowe HF-150 and offers more features. The version with KIWA filter modifcations is well worth the extra cost since Yaesu could have done a better job on the filters. But it is also more expensive. It does not reach the standard set by the Kenwood R-5000, but then it is cheaper. The price of the FRG-100 varies depending on the country. The FRG-100 outperforms older receivers like the Kenwood R-2000 and yet costs much less. Yaesu is therefore to be congratulated for bringing better technology into the mid-range price bracket. This is important, as there has been a growing price gap between portable and semi-professional sets.

This review first appeared on the Radio Netherlands website.