Having now had my ‘Discovery’ transceiver for a while, I thought it would be appropriate to report on its performance. As others have commented, it is an extremely rugged piece of kit, and well able to tolerate the rigors of backpacking and portable operation, even to the extent of surviving the occasional splash. One point, the AF GAIN and RIT/XIT knobs on my unit were very loose. They are made of a rubbery material, and only fixed onto the encoder shafts with a spot of adhesive. They come off very easily, and in portable usage might well get lost. I realise that a spot of cyano-acrylate glue would fix them in place, but then they would be extremely difficult to remove without damage when it comes time to replace the internal clock/memory backup battery. Perhaps someone will make a set of replacements that are secured with grub screws? – Hint – hint!
I particularly like the almost intuitive user interface, after reading the User Manual and spending a few minutes playing with the buttons, it becomes very easy to operate. You have everything you need and nothing you do not. The latest firmware, v1.12.00, adds the facility to correct the internal reference, and in my case only a small correction was required. The ‘out-of-the-box’ error was only +0.35ppm, which is very good. Even so, a small correction was applied and this has virtually eliminated even this offset error.
The manufacturers do not specify the sensitivity of the receiver, so I conducted my own measurements. The standard definition is that signal at the input that results in a 10dB Signal Plus Noise to Noise ratio at the output of 10dB in a 2.4kHz bandwidth for SSB, and a 500Hz bandwidth for CW. I measured this for all the bands individually, and the mean value for the 160m through 10m bands was -120.4dBm corresponding to an input voltage of 0.21uV for SSB, and -125.9dBm corresponding to an input voltage of 0.11uV for CW. For the 6m band the SSB MDS was -117dBm, 0.32uV, and the CW MDS was -123dBm, 0.16uV. For comparison, the Icom IC-705 SSB MDS is specified as -120.97dBm, 0.2uV for the 160 to 10m bands, and -123.5dBm, 0.15uV for 6m. Icom do not specify a CW MDS. Consequently, this receiver is at least as sensitive as the competition, and well suited to portable operation when the antenna is usually sub-optimum.
The panadaptor display is quite usable, and, it can be averaged to smooth out the noise making weak signals more visible – something that Yaesu might well like to consider in their next firmware updates for the FTDX101D, as it constantly annoys me having to look at the raw display on this transceiver.
The quality of the audio from the speaker-microphone is adequate for communications purposes, and there is ample audio power available for outdoor use, especially if you use the increased audio power by setting it to OUTDOOR. Be aware however that the headphone socket on the side of the speaker-microphone is only wired for one earpiece of a stereo headset, which is a nuisance. Much better results can be obtained by using a standard computer boom microphone headset. This plugs into the accessory lead and I have tested it with several headsets, the Yamaha CM-500, Koss SB-45, Trust, Logitech, and the EPOS H3. The latter headset performed the best, with reports of excellent speech quality, as well as being a comfortable fit and good audio in the earpieces. No adjustment of microphone level was required except for the Logitech unit whose microphone output was significantly lower than the others, but there is still more than enough adjustment range available to compensate. If the audio output is connected to a good quality 8 ohm bookshelf speaker, the AM shortwave performance is quite good. Note however that the audio amplifier uses a bridge-mode device and neither side of the speaker is grounded – be careful!
On the down-side, the receiver is not without its share of spurious signals. Especially annoying are two on the 40m band, and one on the 20m band. Most of the spurii are of a sufficiently low level that they are at or below atmospheric noise when connected to an antenna, and so are less likely to be heard. Also annoying are the loud glitches when tuning. This is not a fault, but merely an artifact of the way the synthesiser works. The radio uses a Silicon Labs Si531 PLL Fractional-N synthesiser, and the tracking range of the PLL is limited to about 3,500ppm from its set frequency. Consequently, if you tune further away than this then the microprocessor has to change all the internal multiplication and division registers to a new centre frequency, and this change is what causes the glitch. It might be worthwhile in a future firmware update muting the audio whilst this register change is occurring – just a thought.
Also on the downside, there is no ATU, so either you have to pack one, or else your antennas needs to present a reasonable match to the transmitter. Lab599 have said that an auto ATU that can be attached to the transceiver is one of the things that they are considering, as well as an integrated battery pack.
So, I am very pleased with my transceiver, easy to use, excellent overall performance, compact and rugged, with a really low power consumption in the receive mode, hence 5 stars.
Adrian, 5B4AIY
