ATS-25 RECEIVER (SI4732)

 I got the receiver dispatched few days ago after buying on Amazon. Mine one was priced around 160Euros. I went for the version offered with a soft touch VFO since the experience I had with the traidtional VFO from the ATS-20 was just very bad.

The receiver is sligtly bigger than the ATS-20 and offers a nice dimensions touchscreen for operations.

With its whip antenna - in short waves -it does not pick up any signal with the exception of few strong broadcasters, in Medium wave it just receives the 900 kHz of RAI - Milano which broadcasting center is roughly 50 km away from my home.

With external aerial on shortwave broadcasting bands, it just does the work one is expecting: good signals, fine audio quality, using attenuation features it can also manage quite strong signals without that much of intermodulation and overloading. Basically no difference with other general purpose desktop receivers I own. 

I connected the recevier to two different internal active loops (the GS5-SE + ML3 Grahn Spezialantennen and the AOR LA-400) and also inside the house it gets many signals, also weak ones. During late afternoon and early morning with the AOR LA-400 I could receive all the available broadcasters from Asia (Vietnam, Thailand, Japan, both Koreas, The Philippines, Taiwan),Guam, Mariana islands and also Radio Habana, Radio Marti, WRMI, WWCR. No issues with european stations and midde east ones.

On SSB seems to me that the audio quality of the ATS-20 is slightly better  and also a little less noisy.

I like to remark that the reception with the AOR-LA400 was really amazing and that the small Japanese loop outperformed the Grahn GS5-SE+ML3 when the two are compared on this small ATS-25. This looked weird to me and the testing of the ATS-25 turned into a comparison between the 2 loops on various bands. I must mention that the roof of my house (the shack is just under the roof) is built in wood...basically the same as being outside. 

I thought that next would be to find a loop as small as the AOR with energy supplied by battery instead from the home AC line.

Et Voilà!! I found this (cheap) internal active loop, chinese made, at 80 Euros on Amazon, on ebay it can be found also at just 60 euros. Surely it will not perform as the AOR LA400, but it costs 5 times less. Is called "GA-450 loop" it's smaller than the AOR (only 20cm diameter vs.30cm diameter of the AOR), it covers medium waves and shortwaves from 2300 up to 30000 kHz. And finaly it is powered with a 1000 mAh internal rechargable battery, I have not that many expectations and illusions but let's see what happens when it's delivered.

   

Here following some more pictures of the screen options of the ATS 25.

Usefull features are: the direct input of the fequency from a key-in screen, and the "seek" up and down along the band. The seek functions I would suggest to be activated with a step of 1 kHz search otherwise it simply skips many stations which are indeed there; seeking up down it finds 1 or 2 or 3 stations, surfing the band with manual VFO you find >10. Which is the level of signal below which the seek functions does not stop? Unknown.

Interesting is also the INFO screen with many details on the signal and the reception.

In FM I just made a quick tour: with it's whip antenna signals are there, audio not bad, RDS works.

Country nr. 162: Vietnam

 ricevuta eQSL da XV9HEU dal Vietnam, new country.

Ringrazio!

SI4732 with TinySA spectrum analyzer

I got the TinySA via amazon in 40 days more or less. Interesting application in combination with SI4732 through a cheap Chinese splitter 0-1000 MHz.

SI4732 shortwave receiver

This post is related to the ATS-20 I bought years ago, if you want to read posts related to the various ATS 25 - SI4735/32 I bought later, you can follow these links:

I-05940-MI: ATS 25 PRO+ AIR

I-05940-MI: ATS 25 AMP Receiver

I-05940-MI: ATS25 Max-Decoder (SI4732)

I-05940-MI: ATS-25 RECEIVER (SI4732)

I write this in English because pieces of information related to this just born small receiver, are very scarce. Maybe SWLs "googling" will find this page more comfortable once written in English. First I have to say that this receiver took me almost 1.5 months to get delivered from a chinese supplier, I bought it on amazon at around 50Euro. The time it took to be delivered was exactly as mentioned on the web page where I bought it, so I had no espectations to get this quicker. The small metal box comes with nothing: no re-charging cable, no instructions. Just put into a cardboard box. The various models that one can find on the web may be branded or without any brand, mine one is branded ATS-20 and on the back is written: ATS-20 DSP receiver. Dispite the fact that it is described to cover a certain part of LW (153 khz - 279 khz), mine one covers from 149 kHz to 519 kHz and, connected to a good miniwhip antenna, it receives all the NDB I could test during late afternoon and aslo a couple of Navtex on 518kHz. Working in SSB I could also receive DDH47 on 147 khz tuning with the BFO which can go up and down in a range of -10,000/ + 10,000 Hz covering further +/- 10 kHz! (I stopped at 10,000 Hz..but it goes further up and down...I suspect to 99,990 Hz!!): I could receive the NDB SRN (330 kHz)in SSB at zero beat on 340 kHz with the BFO at + 10,000 kHz. Tuning 149 Khz and the BFO +9,000 Hz I could receiver the upper of the 3 EFR Teleswitching trasmitting station (nominally at 139,9 kHz). But all above is just a curiosity. In MW it covers 520-1720 kHz, in SW in various web pages it's written coverage between 2.3 MHz to 26.1 MHz, my model goes from 1720 Khz to 30,000 kHz, at least these are the readings on the (very small) display, I had not time to test it below 2.3 and above 26.1 MHz, probably it does not receive anything though the reading on the display is available. 

UPDATE:

it receives DSC 0n 2187.5 and FT8 on 10m band (28074 kHz), so apparently it works also above 26,1 MHz and below 2.3 MHz. 

BANDWIDTH FILTERS

Now the bandwidth filters. I have read on the web various values, my model has the following: in SSB = 0,5 - 1 - 1.2 - 2.2 - 3 - 4 kHz; in AM = 1 - 1.8 - 2 - 2.5 - 3 - 4 - 6 kHz. 

DISPLAY

It's extremely small but readable, different models show the s-meter in different ways, mine one gives numbers: "S:1 -2 -3 - 4", other models give one or more lines depending on the signal strength. On the right of the s- meter there's a number 0 followed by a "%" which today were 2 "%%", after switching off and on again it showed a 100% which turned shortly again into a "0%%", I have absolutely no clue of what is that...I immagine it tells the charging status of the battery (??). Pushing the Bandwidth/AGC/Step selectors it turns to "%" and after selection is done again goes to "0%%". Tuning steps of main tunig and of BFO (which is again the main tunig knob after pushing) can be selected at 1 kHz, 5 kHz, 10 kHz in AM and 10, 25 Hz for the BFO steps in USB/LSB. AGC ON, Attenuation Mode, Frquency and Volume are shown as well "here and there" on the display. RDS in FM works pretty nicely, it takes some time to tune and show the broadcasted message, but definitely works. 

BACK SIDE

Two switches are found there: on/off and FM/AM(SSB), the antenna BNC, the USB connection for recharging and finally the 3.5mm jack outlet for a headphone or any other audio connection to a laptop for decoding digital modes, recording, whatever.. 

IN OPERATION 

With its telescopic whip, during the daytime I could get few shortwave stations inside the house, and many spurious signals from a couple of FM broadcasters. Connecting an external antenna, it magically turns into a good enough receiver. I made many comparisons between the SI 4732 and the Tecsun S8800 both connected to the same antenna through a small passive splitter (declared attenuation of 3.5 dB; frequency range of 0 - 1000 MHz; Made in China; Amazon supplied; priced 9 Euro; delivered in 24 hours). On both the radios I could receive same stations with comparable signal quality, of course the sound provided by the built in speaker of the SI4732, has nothing to share with the full and deep sound quality delivered by the Tecsun S8800 which remains - in my opinion - the best audio ever. The audio coming from the SI4732 internal speaker is anyway not that bad: of course connecting a good headphone or a good external speaker also the SI4732 gets to a fairly nice audio quality. During the eveing on 7MHz band, with it's own whip antenna, I could tune various relay stations from Asia on air with programs from the most common broadcasters. In SSB I made just a fast chek on Ham bands, decoding some WSPR in 10m band, listening short QSO on 20m, decoding some FT8 in 40m. Today morning and afternoon I kept it tuned on 12577kHz in DSC receiving with a Falcon OUT 250B: the receiver climbed fast the ranking of the spots sent to YaddNet, reaching rank 2 out of a list of more than 20 receivers connected and spotting. When the battery gets close to be empty, the BFO start making crazy things: switching off and on gain at the same main tuning ad BFO readings, the signal is just not there anymore on the audio spectrum where it should be; re-tuning the BFO, you find the signal again but touching any other button it moves away. I thought this was linked to the almost empty battery, after recharging I could find the signal on the spectrum exactly where it should be with the proper tunig reading for BFO and main frequency. I have to say that on most of the bands the recharger can stay connected without creating noise, using an old mobile phone 5V recharger with a USB socket. 

CONSTRUCTION 

It seems to me a weak construction, the tunig knob has to make many turns to tune up and down the bands, I suspect that soon or late it will break; selectors for options (AGC, step, bands, volume, etc) are really very small even for child fingers; While the box is nice in itself, the front panel could have been designed with some more care to aesthetic. What to espect more than this from a 50 Euro receiver with LW, MW, SW, FM RDS, SSB, DSP?

Una settimana di ricezione in DSC

 Ho i ricevitori accesi da una settimana in DSC giorno e notte, su varie frequenze, ho usato sia l'Airspy HF+, che l'RSPdx e anche vari tecsun, soprattutto l'S-8800e e questo è il risultato ad oggi, ci sono anche Kodiak, Point Reyes e Tokyo che sono state ricevute di notte su 8MHz con RSPdx e Loop Attiva Wellbrook, c'è anche Jakarta (con Tecsun S-8800 + Falcon e MFJ 1020C) che non ricordo se fosse già fra le ricevute o se sia una New Entry.

Lascerò in ascolto ancora una settimana per vedere se riesco a ricevere anche le ultime 4 o 5 che mancano all'appello.

SDR# con finestre ridimensionabili

Ho scoperto che a partire dalle versioni recenti (superiori alla 1.0.0.17XX) SDR# consente di tenere aperte le finestre di maggior utilizzo ancorandole attorno allo spettro/waterfall secondo la disposizione che più gradisce l'utente. Sulla pagina di WB8YQJ è inoltre disponibile una versione aggiornata del plug-in S-meter da cui sono selezionabili le bande di ricezione, l'ampiezza del filtro, il modo di ricezione e che offre la possibilità di mantenere costate il volume in uscita - per altro su un livello che ritengo un po' basso, la funzione è comunque disattivabile.

Nell'immagine di seguito il workspace come da me organizzato.

Ovviamente il Vu-Meter è una app non inclusa nel pacchetto di SDR# ma scaricabile a parte dal sito www.vuplayer.com.

Plugin HF-FAX decoder per SDRuno

 nuovo plugin rilasciato il 19 febbraio sulla pagina web di SDRPlay.

E' un decoder basico per HF Fax. Il plugin - come tutti i precedenti - funziona solo per le versioni di SDRUno da 1.40 e solo per i ricevitori SDRPlay - RSP.

Il ricevitore deve essere lasciato in AM o in FM e la frequenza pari a quella nominale di trasmissione senza correzioni (senza togliere 1.4-1.9 kHz). lo spettro visibile 2MHz e la decimazione a 32.

Il plugin è gratuito.