SWLing Post reader, Marty (W5MRM), comments:
I recently picked up a Sangean ATS-909X to use as a bedside radio.
This blog post inspired me to put together a video review of the ATS-909X as a bedside radio. The video review can be found on my youtube page [or via the embedded player below]:
Great video, Marty, and thanks for the thorough review!
You can follow all of Marty’s videos on YouTube by visiting this page.
SWLing Post contributor, Robert Gulley, writes:
I recently purchased an Oxo Good Grips Turntable, 16” from Amazon. As the photos show, the size of the turntable can hold a fairly large radio (CC Radio EP and Select-a-tenna) on the turntable in almost any configuration. (Of course the CC Radio EP doesn’t need the Select-a-tenna, just used for illustration purposes for size.)
At $16.99 I think it is a good bargain, and seems quite capable of turning smoothly even with this amount of weight.
Click here to view on Amazon.com.
Many thanks, Robert! I think that turntable is large enough to hold pretty much any portable radio; thanks so much for the photos (especially the one your kitty cat photo bombed, above!). I have several OXO products in my kitchen and have never been disappointed with quality, so I expect this turntable will last you a very long time.
Readers: If you haven’t checked out Robert’s radio blog, All Things Radio, I encourage you to do so!
Many thanks to Joris van Scheindelen (PE1KTH)–an SWLing Post contributor from the Netherlands–for the following guest post:
The old mode AM is still an interesting mode for amateur radio communication, also in amplitude CW.
Building your receiver is not difficult and quite fun. The semiconductor industry makes interesting integrated receiver chips today that will be useful for an AM receiver. Not only for broadcast reception but also for amateur AM reception or as part of an AM transceiver.
Silicon Labs also makes Si4734/35 receivers; these need a CPU to control the receiver, but are of interest for amateur use because the frequency can be tuned in 1 KHz steps and the audio channel bandwidth in 7 steps. There is no need for the transmitter to be on the receiving channel…
Looking for a small SW broadcast receiver design, and pocket size, I came to the excellent range of modern DSP receivers in a single chip from Slicon Labs.
I made a test bed set up has been made for the Si4835 AM-FM receiver.
The target specification was:
The Si4835 makes miniature design possible on a PCB (see photo Figure 1).
The red Dip (band) switch was replaced by a rotary switch in the final receiver design (Figure 4).
The receiver power is minimal 2 x 1.2 = 2.4 volts or a one cell LI-ION accu.
5 volts is the maximum for the Si4835 chip; current consumption is 30 mA.
Fig 1. Testbed setup for the Si4835.
The receiver has an RF pre-amplifier transistor and the LF amplifier is the TDA7050T.
All receiver functions are in the chip; the schematic is very simple and can be built with minimal components (see schematic appnote AN555 Fig 2. below).
Only an LF amplifier has to be added to complete the receiver.
Fig 2. Receiver schematic Si4835 in the AN555 application note.
The Si4835 receiver has the following frequency bands–they are divided in sub bands 800 or 900 KHz wide (See Figure 3). The frequency step tuning is 10 kHz on AM, following the international broadcast raster standard.
Fig 3. Si4835 receiver sub bands.
This means there are 80 or 90 receive channels in the sub bands and make finding the BC stations on the scale more easy. The 10 KHz scale steps are linear. The frequency stability is locked to the 32 kHz X-tal via the synthesizer so there is no frequency drift. The AM LF audio channel is 5 kHz wide set by the DSP filter. Volume control can be done width 2 up-down push switches or by a LF potentiometer..
Fig 4. The experimental pocket aluminium receiver housing on PCB2.
Receiving results
I have been testing many hours and I am surprised about this little receiver.
The receiving results are excellent on FM and AM and signals of 2 -3 uV are well received.
Also the audio quality is good–especially on FM. As can be seen in the frequency table the 40 and 20 meter band are in the range. Clear AM phone amateur transmission has been received when the transmitter was tuned on the 10 kHz raster in 40 meter band on AM.
Also AM modulated CW signals can be received bud not un-modulated carrier CW–they sound “plop…plop”.
The 5 kHz wide LF channel is a bid too wide so many CW signals pass through the audio at the time, but if AM modulated that should not be a serious problem.
The broadcast stations in the SW bands (when the daytime conditions are good) up to 20 MHz are good and strong.
Conclusions
The Si4835 receiver can be a fine broadcast receiver for outdoor work and if an AM transmitter is tuned in the 10 kHz raster this receiver can also used for amateur phone reception.
Addendum: The Si4734/35 is a better amateur AM Receiver
The Si4734 and Si4735 are a better receiver choice for amateur AM purpose because the frequency tuning can be done in 1 kHz steps. Also the BW of the LF channel can be adjusted to 1 kHz wide.
In Fig 5. from the programming APP note you see the code 0X3102 AM CHANNEL_FILTER it is possible to adjust the audio width by sending this code to the Si4734/35.
Fig 5. From the programming APP note
The LF bandwidth can be set on 1, 1.8, 2.5, 2, 3, 4 and 6 kHz wide.
This is excellent for modulated CW and AM phone discrimination in the audio channel.
The disadvantage is the need of an CPU and LCD display, “away from a minimalistic design”.
See also the note 1 and 2 improved 100 Hz rejection. See data sheet of the Si4734/35.
It look like that this receiver is a good receiver for building a modern AM-(AM)CW receiver or in a transceiver application. Tuning can be done digitally.
Think about this receiver [and the Si4835 chipset] when you intent to build a high tech AM – T/RX.
73 ‘ Joris van Scheindelen PE1KTH
What a fantastic home-brew receiver, Joris! I love the simple design of your receiver and the fact that it’s quite portable. Thanks so much for sharing your notes and documentation.
SWLing Post reader, Frank, writes from Germany:
First let me say that I enjoy your blog a lot.
After a 2005-13 hiatus, I have rediscovered a childhood hobby and your reviews have helped me find my way to the post-Sony portable shortwave radio markets.
First, I obtained my “childhood dream” radio (Sony ICF 2001D), because at the time I made these recordings I was still in school and 1300 DM would have equaled over 1 year of pocket money, so a Supertech SR16HN had to do. I thought I got some fine results with this Sangean-Siemens re-branded receiver then, using a CB half-length antenna, a random wire, and much endurance.
The Supertech SR16HN (photo: Radiomuseum.com)
I kept regular logs throughout the years, wrote to 50 international and pirate stations for QSL and compiled this cassette.
A few years before I got that trusty SR16HN, however, I recorded a few number stations (such as G3, Four Note Rising Scale etc) with an ordinary radio cassette recorder, and in 1991 I put them onto this tape as well. The other recordings are done with the same radio placed right in front of the SR 16HN.
Feel free to make use of these recordings. Most of it are the well-known international state-owned shortwave stations of the past; plus European pirates; plus number stations; and at the end, a few (off-topic) local Am and FM stations interval signals.
As I said, this collection I made shortly after the Wende/reunification period, when all former-GDR state broadcasters changed their names, sometimes more than once.
Please continue your good work on the blogs! Weather permitting I am often outside cycling and always have the tiny Sony ICF 100 with me (which I call my then-student’s dream radio of the later 90ies).
Frank’s original hand-written notes. Click to enlarge.
Click here to download Side 1, or listen via the embedded player below:
Click to enlage.
Click here to download Side 2, or listen via the embedded player below:
Wow! Frank, what a treat to listen to all these station IDs!
I had forgotten how many interval signals have changed over time and how many, of course, have disappeared. This tape represents a flood of nostalgia for me.
I should add, too, that I’ve enjoyed hearing so many IDs in German. It’s funny, but we all get hooked on listening to language programming from our native or second languages. It makes me realize just how many broadcasters used to have German language services.
Again, many thanks, Frank, for taking the time to digitize these recordings and scan your original hand-written notes. This stuff is invaluable, in my book!
Many thanks to SWLing Post reader, Bill, for sharing a link to this article which summarizes the BBC’s plans for the next ten years.
BBC director general, Tony Hall, said the corporation will become an “open BBC for the internet age”.
While Hall was quick to add that funding cuts would equate to “the loss or reduction of some services” he also highlighted several efforts that would include shortwave and mediumwave broadcasts, including:
Of course, we can expect more cuts to BBC World Service shortwave broadcasting over the next ten years even if it wasn’t specifically mentioned in Hall’s speech. If we’re lucky, the BBC will continue to broadcast into those parts of the world that still rely on shortwave. Specifically mentioning North Korea, Ethiopia and Eritrea appears to be a nod in that direction.
Click here to read this article on the BBC News website.
Also, The Guardian has posted the full text of Tony Hall’s speech. It’s worth reading.
SWLing Post reader, Evans (in Greece) writes:
I would like your opinion regarding two strange points we noticed in two different Tecsun PL-880 models, which a friend and I have recently purchased. In particular:
The signal meter is supposed to measure up to 99dBu (my Tecsun PL-390 s-meter goes indeed up to 95-97dBu for very strong amateur signals in my area included mine in mw zone). The point is that for both devices (both of which have 8820 firmware) the signal meter does not exceed 85 dBu and in particular my Tecsun PL-880 signal meter does not goes over 70dBu (ie. even lower measurement). Why this behaviour?
Another strange point is that my friend’s Tecsun receiver displays for a “quiet” frequency (mw) a noise level of about 10-12dBu, while my Tecsun device shows only 2-3dBu noise (same frequency in the same spot!). We both tried the threshold muting adjustment (key 9) and this worked a bit but with minor results in sensitivity, especially for my Tecsun PL-880 receiver. Is it possible to adjust the noise level so that it can be 10-12dBu instead of being only 2-3dBu and hence better sensitivity? And is it possible to adjust the maximum signal level (99dBu instead of 85dBu or even worse 70dBu for my device)?
I have noticed that the hidden feature regarding the external mw antenna didn’t work in my case, even though I did resets an tried many times. I pressume, hence, that maybe Tecsun disabled this hidden feature. Is there any modification available to “add something” into the radio hardware in order to be able to listen mw/lw frequences with external antenna and thus, increase sensitivity?
Many thanks for your questions, Evans. Since my PL-880 is a first production run unit, I’m hoping readers who’ve recently purchased the Tecsun PL-880 might comment.
I suspect Tecsun engineers give little thought to calibrating the S meters. I’m very curious if there is a hidden feature to do this, but I’m guessing this is limited only to those who can program the DSP functionality of the chip inside.
Many thanks to SWLing Post contributor, Moshe, who writes:
About 2 weeks ago, a very good friend called me and exclaimed, “you just have to see this radio…I’m keeping it for you!”–so, I drove to his aunt’s house and saw this beauty.
After hauling the radio to my place, I started to check it out, to see what would be needed for restoration; it was working, with bad contacts, poor frequency response and low output.
I took hi-res pictures of this radio, some during restoration. Now the radio sounds great. It has been recapped, a couple of bad resistors and bad wires replaced, contacts have been cleaned, and some good cleaning for the chassis as well.
As I wanted to keep the original appearance of the chassis, I kept the original filter capacitors on board, but disconnected them from the circuit, added terminal strips and new capacitors from underneath.
The radio uses an EF85 tube as the RF stage. With the addition of a grounding connection and random wire antenna, it’s very sensitive on shortwave.
About the Ben-Gal Duet-Stereo:
It was made in Israel by Ben-Gal, a label inside shows it was made at 12th of December, 1965.
It is a console model with record player. As the model name suggests, the amplifier and record player are stereo (though the tuner is not…).
The radio has longwave (marked in meters), mediumwave (marked in meters) and 3 shortwave bands (with megacycle and meter band marks).
The shortwave bands overlaps with each other, so cover is continuous:
- SW3 2.3MHz to 6MHz,
- SW2 5.5MHz to 15.5MHz,
- and SW1 14.5MHz to 23MHz.
Many thanks, Moshe, for sharing photos and this description of this beautiful Ben-Gal Duet-Stereo. I bet the audio fidelity is amazing. My father has a 1960’s console–with a similar configuration–made by Admiral, though it was limited to mediumwave and FM reception. Some day, I will try to restore it to its former glory!
Thanks for the inspiration, Moshe!
