martedì 25 dicembre 2018


Ricezione di frammenti di un messaggio Navtex da Bangkok Radio (HAS) su 518kHz il giorno 24/12/2018. Ore: 20:57Z
RX: Airspy HF+
Antenna: Miniwhip PA0RDT

domenica 16 dicembre 2018


FO5QB da Tahiti, ricezione di un QSO in JT65 in banda 20m

domenica 9 dicembre 2018

Personal evaluation of the Tecsun S-8800e

I have already written all my positive impressions on the Tecsun S-8800e in another post here in my blog. But: since I get a lot of emails asking more and more information about this receiver which are mainly coming from abroad Italy, I like to make a new post in English. Sorry 'cause my English is not that good, but I hope I can manage to make it understandable as much as I can.

I own this receiver since March 2017, I bought it from the European dealer for 355 euros delivered to my home. Nowadays you can find on the web at 315 Euros + transport. It's a little expansive but surely less than other SWL receivers of wellknow brands which basically provide just a little more of performance and filters. One remark on price, in Australia on the web page of the local distributor, the device is sold at 380 $...which I guess are Australian Dollars, if this is the situation, then I have to remark that at today's exchange ratio, 380 AUD are 239 Euros, means that SWLs from that part of the world may benefit of a much fair price than we here in Europe.

In two years with the Tecsun S-8800e I could receive almost everything in the SW band; in all digital modes for Ham Radio (JT65, JT9, RTTY, PSK, FT8) and for utility broadcasting (SITOR, DSC, HF FAX, RTTY) receiving stations from all continents. Even difficult coastal stations could be received like GMDSS calls from Curaçao Island Radio on 2187.5 kHz or AAsiaat Radio from Greenland as well on 2187.5kHz, same frequency Shangai MRCC in GMDSS. The most interesting receptions in HAM radio were VK9MA the DXspedition from Mellish Reef Pacific Ocean received in FT8, 3D2TS from Fiji Islands, ZF1DM from Cayman Islands.

In MW band all the Navtex stations which can be received in my area on 518 kHz were copied and decoded, same on 490 kHz.
I am not using this receiver for NDB hunting, for this activity I prefer much more the use of an SDR because having a look at the full reception band on a waterfall helps a lot to identify NDB signals which are affected by strong QSB in short timeframes.
I am not using this S-8800e even for MW DXing where, as well, I prefer to have a look at the full spectrum on the waterfall because this helps identifying signals at 10kHz steps - like the US stations - from ones which are distributed on the MW with 9 kHz steps - like European stations. I anyway use this receiver in MW for general listening purposes due to its "warm" and "full" sound which makes me satisfied a lot.

In LW broadcasting activity is limited to maximum 15 broadcasters which I can receive 24h a day connecting an external antenna to the high impedence connections on the back of the device. For this use I normaly connect my PA0RDT Miniwhip with a proper connection adaptor. I use two short pieces of wire connected to an adaptor banana-BNC, the miniwhip fits with the BNC adaptor.

Few words on VLF reception: the S-8800e differs from the standard S-8800 because the European version can receive down to 20 kHz, it can be identified from the S-8800 standard, because the switch on button is green instead of red, in both the devices the model is identified as S-8800 without any "e" after the number, thus the colour of the button is the only way.
We should keep in mind that in VLF this is not a superperforming receiver. Below 30 kHz the receiver is almost deaf, moreover it does not receive in CW so all frequencies are to be tuned almost 1 kHz lower (e.g. DCF77 has to be tuned on 76.5 kHz instead of 77.5, MSF on 59 instead of 60 kHz, etc..). Last: to have an acceptable reception inside the house you need a proper external antenna like the above mentioned Miniwhip otherwise with the internal ferrite antenna you can just receive (barely) the DCF77 and the three EFR radio stations between 128 and 138 kHz.

I would say that to have a portable receiver like this with VLF, is just a matter of owning an oddity or a curiosity for radio collectors. Should you like to do serious VLF reception with the Tecsun S-8800 please consider to buy a VLF upconverter, I have one from Eelettrofficina and with this non expansive device you can get a lot of fun in the low frequencies. With this setup I could receive the beta time signal of RJH66 from Biskek Kyrghizstan on 25 kHz VLF (28025 kHz with upconverter), SAQ 17.2 kHz (28017.20 kHz with upconverter).
Otherwise if you are really interested in VLF reception a good SDR, a marine professional receiver as my old ITT Mckay Marine type 3031-A or a selective level meter, would do this job in a better and cheaper way.

The Tecsun S-8800 is claimed to be affected by birdies, which I believe. The point is that I could not identify, in mine one, as many of these birdies as others are claiming. I could identify around 5 to 10 birdies all in reception bands where there's almost nothing to listen in my location. So in this case my approach is: who cares as long as there are not hundreds of birdies.

The receiver is supplied with a remote control from where you can operate the device very easily. Unfortunately this is not what I like to do: I prefer to push buttons and to turn knobs by hand. During first operations I noticed that the receiver is quite light and turning the frequency knob with one finger may results in making it falling down. This I solved building a wood box which takes the receiver always standing, also during fast tuning.

Other aspects for operating the receiver are OK; the only things that I would make different are the switches on the right side of the radio. There are two switches: for DX-Local (attenuation) and for selecting internal-external antenna. There is not a reason to have them different from now: to me they are just uncomfortable. Using the high impedence antenna for MW-LW-VLF, the switch internal-external aerial, seems not to be effective as if the external antenna is always connected somehow to the internal ferrite rod by some kind of induction or in another way.
The receiver is able to manage strong signals and within certain limits there's no overload, but in MW-LW-VLF, connecting an external antenna the s-meter is almost always on the maximum value either with a station tuned or outside any tuned signal. Wherever you are tuned the s-meter is anyway 5 and using the attenuation Lo-Dx there's no effect on this. I would comment that for a receiver in the 300 euros range, this could be improved, even the PL 880 (which I bought 2 years ago in Hong Kong) has a much better signal measurement.
A good improvement in the S-8800 - compared with the PL 880 - is the possibility to tune the volume of the audio line out. In the S-8800 this can be done using the volume buttons of the remote control. I could not find any way to do this on the PL-880 with which you must work on the inlet volume of the lap top sound card.
The big volume Knob on the S-8800 just change the volume at the headphone or at the speaker, but not the one of the audio line out.

Sound management is the best feature of the Tecsun S-8800e, bass and treble knobs improve efficiently the sound quality. The 4 bandwidth filters available for AM reception are well effective with amplitudes of  2.3 - 3 - 4 - 6 kHz as visible in following picture, lower part of waterfall is 6kHz wide filter, while upper part is done with 2.3 kHz filter (received station is Chaine 3 Algerie on 252 kHz LW)

In SSB the story is slightly different, in theory the receiver provides 5 filter amplitudes at 0.5 - 1.2 - 2.3 - 3.0 - 4.0 kHz, the point is that - in the device I own - I do not see any difference for 4 and 3 kHz filters. This is clearly visible in next picture.

at 18:32 I have changed filter width from 4 to 3 kHz without any difference in the waterfall, while most of the signal "ends" at around 2.7 kHz, at 18:33 filter width is changed down to 2.3 kHz with a visible effect in the waterfall, at 18:34 the filter is changed to 1.2 kHz and before 18:35 is changed again down to 0.5 kHz.
Out of all this filters story I can conclude that in SSB the real usefull maximum width of the spectrum is no more than 2.7 kHz. This can be an issue for example once you want to decode JT65-JT9 together in same decoding session using WSJT-X. Same problem I noticed on the PL-880.

The receiver is full of features which I do not use for example it comes with an extensive number of memory slots for storing preferred stations, in relation to this you can read the user handbook available on the web in pdf format. For me is just easier to dial the needed frequency than remembering the slot number where it is stored. The Tecsun S-8800, like the PL 880, has hidden features which you can find here in the blog in an older post (in Italian).
If the expectations of a buyer for a portable BCL receiver are not too high, the Tecsun S-8800 will be amazing and the owner will love it as I do. For utilities and HAM Radio bands reception I personally  found this receiver great for the price, same for Broadcasting stations in short waves. MW and LW could be improved: for example on Navtex frequency 518 kHz sometimes the receiver goes almost muted as if overloaded, but even in this way Navtex signals can be decoded although the volume on the decoder is equal to zero. Tapping on the LO-DX switch this muting goes away but it may come back in a randomic way. During evening reception, using an antenna which is providing a strong signal (like the miniwhip) many spurious signals can be identified, this happens mainly in LW and VLF. In this case the use of the attenuation (LO-DX) provide an efficient solution without affecting the quality of desired signals.
Anyway since facts are better than words, I can suggest to browse my blog, click on the tag "tecsun S-8800e" there are many posts of great receptions that I did with this receiver.
Finally would I buy it again in case of need? Surely yes.