On what basis can we select a transceiver ? What features made the difference between a mid range and a high end model ? Is the price a good indicator ? Are DSP functions and filters useful ? Here are some among thousands questions that run through our mind when we decide to buy a new RTX without having a deep knowledge of the technology used in such rigs and new developments in both hardware and built-in software.

To clarify the problem, let's take a practical example. Proceed from lived experiments of hams using both the mid range Kenwood TS-570D and high end like the Icom IC-775DSP, Kenwood TS-850S or Yaesu FT-1000 MARK V, three models that are about three times more expensive than the first.

Hams having worked with these RTX will recognize that depending your activities on bands, these both categories of rigs give not similar results in the field. There is on the one hand what says the marketing, and on the other hand what are using hams.

According several experimented contesters, the TS-570 is a fine receiver for casual, non-contest operations. In short, as I explained in my review of this RTX, the TS-570 DSP noise reduction is great, and with the optional 1.8 kHz SSB filter, selectivity is good – a reason I bought it contrarily to the opinion of some hams !

Take now the Icom IC-775DSP. The main reason for buying the IC-775 with options is to participate in more contests. This is where the Icom excels, and still more equipped with all optional filters, a Heil Sound mic, appropriate big guns aerials, and maybe an amplifier. But even using its default settings the IC-775 allows narrow filters at two IF-stages (TS-570 only allows one). What is the result ? The Twin Passband Tuning used in conjunction with the two 1.8 kHz filters in the IC-775 is far superior to the IF Shift method provided on the TS-570. With the manual notch filter, there is nothing you cannot filter out. On 160 m also, when adding attenuation, turn off DSP, you can open the filters to 8 kHz for hi-fi audio, what the TS-570 could never perform.

Under strong Q-signals the IC-775DSP receiver does not overload or desense like the much cheaper TS-570. The sensitivity is about the same, as you would expect because the TS-570 is really a great rig in its category, providing an excellent signal and a good reception in usual working conditions. As I explained previously, when the propagation is there and no QRN at all on the band, filtering is even useless and both rigs yield the same results ; they are really on par. Also, before reselling your TS-570, think rather twice than one as it can be a great performer for working abroad, e.g. on holidays or in the field as a portable RTX (even on dry battery) although the IC-775DSP is still small enough to be handled but it is much heavier.

On the other hand, while contesting against world class competitors, you need either an original method to bypass the QRM either of bigs guns to reach the highest scores, what means to get the largest numbers of contacts in being able of discrimining any incoming call. With that objective in mind with all optional filters installed in both IF-stages of the IC-775DSP, and a good headphone mic or an external DSP speaker (the internal is still good compared to most others), this radio can have unbelievable selectivity and audio. But probably not as selective as the built-in Collins filters installed in the Yaesu FT 1000 MARK V or in the Field version..

The Collins filters (made of solenoids) installed in the Yaesu FT 1000 MARK V push the selectivity of this transceiver and thus its performances a bit more far than any other RTX. The contour of Collins filters passband is very effective at removing noises on sideband, without impacting the desired signal. The profile of these Collins filters is similar to a square wave what allow you to eliminate very easily a QRM located a fraction of hertz near your frequency. Better, the Yaesu FT 1000 series is completed with analog filters to extract the weakest signals from QRM. With this both kinds of filters no signal can be lost on the QRM.

On the contrary, using integrated circuits digital filters enveloppe looks more like a gauss curve than to a square wave and you can never reach performances of a Collins filter; with such specs the weak signals that are not completely filtered at both extremes of the filter passband can still be heard. For decades Collins filters, they be internal of external, proven their quality. Of course such filters are expensive, over 250 euros per filter, and you need as much filters as you have bands to work (one for the 40m, one for the 20m, etc).

On the other side DSP noise reduction options found in most RTX are powerful features. In usual conditions the adjustable noise blancker of the IC-775DSP is one of the best that you could hear. The 9 O’lock position (offering the greatest N.R.) is perfect for all but very noisy conditions. Cranking the noise blancker all the way helps you eliminating even the most stubborn pulse noise like power lines noises that other NBs (like the TS-570) won't touch, without compromising audio quality. SSB audio is very customizable for either fidelity, or cutting through a pile up using compression. However the Icom 775DSP cannot reach performances offered by the Collins filters installed in the Yaesu FT 1000 MARK V.

Filtering : DSP or Audio stage ?

If you are only interested in CW, a filter placed on the audio stage is more than enough to get good results. Autek QF-1A is for example an excellent product.

But a DSP doesn't work the same way, and in SSB it removes automatically carriers that fall in the current passband, and this without using a notch circuit... a great improvement.

The passband of a DSP is also programmable to get abrupt wings contrary to an audio filter that displays a bell shape. The first is thus "better".

At last, the elimination of noise is ruled by signal processing protocols (maths), whereas an audio filter depends of its bandwidth... which affects the audio and therefore, it is not always suited to the mode used.

In selecting a filter, keep in mind these reference parameters when comparing performances of your filters.

Generally speaking we can however say that a DSP is more versatile as it can be used with most modes of traffics.

Power side, the IC-775DSP transmitter develops 200 W and does not even get warm during long SSB QSO or at 100 W using PSK31. This supplemental power may add a half dB to the TX signal, improving a bit a CW signal lost in QRM, or can be useful in driving an amplifier. The cheap TS-570 is menu driven, which slows down operation in contest. On the contrary, with the IC-775DSP or the Yaesu FT 1000 series all commonly used controls have a button or knob on the front panel.

At last, as many high end rigs the IC-775DSP has a sub receiver, although not as flexible as the Yaesu FT 1000 series, that allows you to listen at 2 frequencies at the same time. Why using a double VFO ? Imagine there are two pile-ups working on the 20 and 10m bands. If the 20m station is hard to work you can switch to the 10m band and try to work the second DX, keeping an ear on the lower band waiting a lull in the traffic. A double VFO is also very appreciated in CW (or even SSB) when working a DX whose QSX frequency shifts regularly of a few kHz. So such a feature is great for spots and split operations. The TS-570 has well an A/B VFO push-button that can be very useful in SSB where DX stations work usually at fixed QSX frequencies (i.e. up 5) but it makes DX spotting working in CW difficult at best !

So, is the Yaesu FT 1000 MARK V (or any high end transceiver for that matter) worth the price? Well it depends. Over three as expensive as the TS-570, a rig at 3000 euros can be a great performer but it will allow you to buy a lot of antenna, a linear or external filters too. But if you already have a great spot and the best aerials you can buy, e.g a beam cut for each band 60’ high installed in a high open field or at sea level, a better receiver may be the way to go. This is also the best choice if you want to replace all your old material (your smallest RTX, external filters, AT tuner...) by a high end model including all these features from factory.

Of course if you do not want operating in contests or in heavy QRM conditions, or if you are a casual operator or SWL I would go with the Kenwood TS-570 series. However, even as a "little-gun" contester, without hesitation you should consider buying theYaesu FT-1000 MARK V or one of its challengers, the Kenwood TS-850S or even the Icom IC-775DSP. Even if the Kenwood still uses analog devices – it was designed in early 90’ – its performances exceed most of recent models, and these radios clearly trade off size for usability. So if you are searching for the best rigs, both RX and TX sides, these three transceivers count among the finest HF transceivers ever made !

Make the good choice.