Category Archives: Homebrew

BITX40 now goes digital

Earlier this year, Farhan of BITX20 fame, released a 40m version of his famous transceiver. The difference this time was it was not just the schematic with detailed instructions, but a full kit, for the princely sum of $45 (about £35 GBP). And this is an almost ready to go kit, with all onboard components already fitted. These boards are assembled by a team of ladies in India, and provides them with employment. All the user has to do is select a suitable enclosure and with some basic metal bashing skills, put together a decent single band SSB transceiver, with 6-7 watts of RF output.

One of the observations of many early adopters of this kit was it suffered from drift, due to the varicap tuning arrangement. Also, tuning with the supplied pot was somewhat critical, and many users purchased a 10-turn pot to overcome these limitations. Yet others have put together Arduino-based VFO’s with digital readout etc.

Farhan has now addressed these comments and produced a version complete with Arduino-based digital VFO + readout for $59! This is a real winner, and I am being seriously tempted to purchase the kit. I have been ‘off-air’ for many years due to the reduced level of conduct on the HF bands, but this kit may just tempt me back. It would provide an ideal back-pack or SOTA rig, powered by a 12v gelcel.

For more details about this kit see the HF Sigs website

National RF 75-NS-3 receiver kit

From the SWLing Post blog comes news of this receiver kit from National RF. While I think the pricing is a bit on the high side, it is good to see companies offering this sort of thing. Costs could probably be reduced by not offering it with the board pre-stuffed which would also make it a much more interesting build. And it would have the teaching element in it too.

National RF, of California, has introduced a new “semi-kit” receiver: the RF 75-NS-3. Here’s an excerpt from the product description page of the National RF website:

National RF’s 75-NS-3 receiver is a complete super-hetrodyne mini high frequency receiver, designed specifically for the short-wave listener, electronics enthusiast or radio amateur, who wants to use their hands and build a radio. The receiver is offered as a semi-kit in which the electronic assembly is loaded and functionally tested at the National RF facility. The customer must then go to the grocery store (yes…the grocery store!), procure a can of [Spam] lunch meat, eat it or give it to the dog, and then proceed to drill and paint the can, in order for it to become the receiver’s enclosure! […] Detailed drilling instructions and final assembly instructions are provided as part of the kit. All other parts required for completion of the receiver are provided as well. Recognizing that the finished assembly looked somewhat like the fabled Collins receiver of the ‘60s, the 75S-3, (particularly when the can is painted a light gray) National RF engineers dubbed it (with tongue firmly planted in cheek, of course) the 75-NS-3! Although we have had fun packaging this receiver in a lunch meat can, it is nothing to turn your nose at! Its performance and portability will surprise you, and it is an ideal radio to bring with you on any trip!

The receiver architecture is that of a single conversion super-hetrodyne receiver, that is capable of receiving AM, SSB, or CW. The receiver incorporates a dual gate FET as an RF amplifier with manual peaking and gain controls. A ceramic filter is used in the IF section with a front panel switch that controls a broad or narrow IF response. Other front panel controls include audio drive, BFO setting, and a band switch for the HF bands. The 75-NS-3 has internal receive frequency coils that are switched at the front and rear panels. The frequency range of the receiver, over three band set positions, is 3.5 through 12 MHz. This allows reception of several international short-wave bands, the 80, 60, 40, and 30 meter amateur radio bands, and of course, WWV time and frequency standard stations at 5 and 10 MHz.

For those who simply want a lower cost receiver to monitor the shortwave frequencies, National RF offers two variants of the original receiver: the 75-NS-1 and the 75-NS-2. Both are based on the design and circuit of the 75-NS-3, but do not have the band switching and frequency range of the 75-NS-3 receiver. The 75-NS-1 covers between 3 and 6 MHz, including the 80 and 60 meter amateur band. The 75-NS-2 covers between 6 and 12 MHz, including the 40 and 30 meter amateur bands. Both units have the fixed ceramic resonator band width set for about 6 KHz. And, of course, they are both designed to fit in the tasty potted meat can!! All other specifications presented apply to both of these models as well.

Pricing of the 75-NS-x versions:

  • Type 75-NS-1Mini HF Receiver Semi-kit (covers 3 to 6 MHz) $189.95
  • Type 75-NS-2Mini HF Receiver Semi-kit (6 to 12 MHz) $189.95
  • Type 75-NS-3Mini HF Receiver Semi-kit (band switched from 3.5 through 12 MHz in three switched positions) $269.95
  • Shipping and Handling to within the US $10.00 each

Click here to view on the National RF website.


Logs from 2nd September 2015 and some antenna work

I have some holiday this week, so amongst other things, I decided to get a new antenna up, something I have been wanting to do for a while. My original plan was for a dipole with each leg about 50′, but on looking at how I would squeeze this into my small plot, it wasn’t possible. Well, one leg was, but not the other! So, as in most ham things, time for a compromise. A few years ago I had successfully used a half size OCFD (Off centre fed dipole), with one leg of 44 feet and the 22 feet, giving an overall length of 66′. Fed with open line feeder, this tuned 7 Mhz – 30 Mhz with the use of a tuner.

So this was what was erected yesterday. This time I used 450 ohm line as that’s what I had in the cable bin, and instead of running it through a tuner, I just use a 9:1 unun, as at the moment I am receive only.

Initial tests seem to give improved signal strength over the 45′ long wire I was using. Conditions yesterday, and especially last night, weren’t that good so it is hard to tell yet.

Being on holiday has also given me the time to do some listening during the day. This was nice as there a lot of stations on I don’t normally hear. A new country for me was Eritrea, having logged the ‘Voice of the Broad Masses’ station last night.

So, onto the logs:

15735 Khz Uzbekistan R. Japan 14:13 UTC English. News about Japan including details about a joint US/Japan military exercise. ID at 14:15. Followed by ‘R. Japan Focus’ program. Details about how Japanese immigrants moved to Brazil, along with the music from a Japanese singer with songs about these immigrants. Some QSB on the signal. The broadcast ended with ID and schedule information from 14:29 – 14:30 SINPO: 42344 2015-09-02

15825 Khz USA WWCR 14:33 UTC English. Religious broadcast SINPO: 42333 2015-09-02

13590 Khz Thailand VOA Deewa Radio. 14:40 UTC Pashto. Discussion program with male announcer. SINPO: 43333 2015-09-02

13760 Khz North Korea V.O. Korea 14:44 UTC French. Male announcer with news. SINPO: 43333 2015-09-02

11540 Khz Thailand VOA R. Ashna 15:40 UTC Dari. Male announcer SINPO: 32233 2015-09-02

11630 Khz Kuwait R. Kuwait 15:44 UTC Arabic. Female announcer with background music. Followed by further music. SINPO: 33333 2015-09-02

11700 Khz Swaziland TWR 17:30 UTC Amaric. Male announcer. Heavyily splattered by CRI on 11710. SINPO: 31233 2015-09-02

11735 Khz Zanzibar ZBC 17:36 UTC Swahili. Female announcer. Discussion program with background music so I guess its a musician. Some interference from R. Belarus on 11730. Pop music followed this. SINPO: 33333 2015-09-02

11770 Khz China PBS Xinjiang 17:44 UTC Chinese music. SINPO: 33333 2015-09-02

11985 Khz Northern Marianas RFA 17:54 UTC Korean. Female announcer. ID at 17:55 SINPO: 43333 2015-09-02

12005 Khz Sri Lanka R. Farda 17:56 UTC Farsi. Male announcer with discussion program. SINPO: 43344 2015-09-02

12065 Khz Australia R. Australia 18:00 UTC English. ID followed by news. Female announcer. After the news, ‘Life Matters’ program. SINPO: 43344 2015-09-02

12120 Khz Phillipines R. Philipinas 18:07 UTC Mixture of English and Philipino. Female announcer with news. SINPO: 33333 2015-09-02

7175 Khz Eritrea V. of The Broad Masses 18:20 UTC Music. Occassionally blotted out by a Ham tune-up tone. Music followed by male announcer in Arabic. SINPO: 32223 2015-09-02

May logs

I thought I would post all my logs for May, as I haven’t had much time for individual posts. As mentioned in one of my posts, I am now using a homebrew pre-selector with the Tecsun Pl-600, and this has improved reception a lot. Not only does it peak up the signals well, but it removes all the image frequencies I was receiving previously. Well worth the effort and it was nice to do some homebrewing again.

May Logs

17895 Khz USA VOA 18:14 UTC English. Discussion about Burundi. Some deep QSB AT TIMES. SINPO: 44444 2015-05-02

15190 Khz Phillipines R. Philipinas 18:25 UTC English. male and female announcer. I think they are talking about low paid service workers. SINPO: 32233 2015-05-02

15275 Khz Madagascar DWL 18:35 UTC Hausa. Discussion program. Madagascar relay SINPO: 33333 2015-05-02

15400 Khz Ascension Island BBC 19:00 UTC English. ID and news at 19:00. SINPO: 43333 2015-05-02

15480 Khz Madagascar AWR 19:11 UTC Arabic. Discussion prog. SINPO: 43333 2015-05-02

15650 Khz Greece Helliniki Radiophonia 19:23 UTC Laid-back Jazz SINPO: 43333 2015-05-02

13580 Khz Bangladesh Bangladesh Betar 19:29 UTC Bangla. Discussion with mention of Bangladesh. Followed by music. SINPO: 43333 2015-05-02

13695 Khz India AIR 19:34 UTC English. Discussion about devolution of power to Scotland and Wales. Other news about the forthcoming UK election. SINPO: 33333 2015-05-02

12120 Khz Phillipines R. Philipinas 19:22 UTC English. ID and jingles at 19:22 followed by music. SINPO: 32233 2015-05-04

11635 Khz North Korea V.O. Korea 19:35 UTC English. Korean music SINPO: 43333 2015-05-04

5865 Khz Kuwait R. Farda 21:08 UTC Farsi. Music followed by ID at 21:10. Male announcer with further music from Gilbert O’Sullivan! SINPO: 33333 2015-05-05

6050 Khz Tibet PBS Xizang 21:14 UTC Chinese. Usual near non-stop music from Lhasa. Very nice. Occasional voice over. SINPO: 43333 2015-05-05

6080 Khz Botswana VOA 21:25 UTC English. Pop music. Some QSB. ID at 21:32 SINPO: 43344 2015-05-05

6115 Khz Phillipines R.Veritas Asia 21:44 UTC Chinese. female announcer with chinese music. SINPO: 32222 2015-05-05

6150 Khz Germany Europa 24 21:46 UTC Playing Elton John, Bee Gees etc. SINPO: 43333 2015-05-05

13580 Khz Bangladesh Bangladesh Betar 17:56 UTC English. News about Bangladesh and India. Female announcer.After 18:00 the signal became very poor and the modulation seemed to be reduced. ID, with frequencies and languages at 18:02. SINPO: 44444 2015-05-06

13630 Khz Botswana VOA 18:06 UTC Portugese. Male ann. SINPO: 43333 2015-05-06

13605 Khz USA R. Marti 18:52 UTC Spanish. Male and female announcers with discussion. SINPO: 32233 2015-05-06

7465 Khz Albania R. Tirana 19:48 UTC English. Male announcer with news from Albania. Followed by Press review. A musical segment followed this and then economic news about Albania, with a projected 1.8% increase in the economy. Information followed about an Albanian musical instrument (I missed the name), a form of drum. Until 20:00. SINPO: 33333 2015-05-07

11725 Khz New Zealand RNZI 19:22 UTC English. Economic news. SINPO: 33333 2015-05-10

15120 Khz Nigeria V. Nigeria 17:50 UTC Arabic. Male announcer. Terrible modulation with a permanent humming over the signal. SINPO: 42244 2015-05-17

9310 Khz Thailand Deewa Radio 17:40 UTC Pashto. Male announcer. Several mentions of Pakistan. SINPO: 43344 2015-05-18

9410 Khz UAE BBC 17:47 UTC English. Male and female with news. Diicult to follow as severe drop-out of signal (doesn’t sound like fading). Dhabbaya relay. SINPO: 33333 2015-05-18

9515 Khz South Korea KBS World Radio 17:51 UTC Korean. Male announcers. SINPO: 43344 2015-05-18

9600 Khz South Africa AWR 17:55 UTC Masai. Chat and local music. Dead air at 17:59 SINPO: 32233 2015-05-18

9710 Khz China CNR1 18:03 UTC Chinese. Music then dead air at 18:05. Shijiazhuang transmitter SINPO: 32222 2015-05-18

9720 Khz South Africa BBC 18:07 UTC Somali. Male announcer. Heavy QSB and QRN. Meyerton relay SINPO: 32233 2015-05-18

9730 Khz Vietnam V.O. Vietnam 18:10 UTC Spanish. Signal initially poor, then after a crackle or two, the signal came right up. Female announcer. ID at 18:13 SINPO: 44444 2015-05-18

9755 Khz South Africa R. Japan. 18:16 UTC English. Japanese lessons. Meyerton relay. Some heavy fading at times. Following the lessons were details of a competition. ID, frequencies and sign-off at 18:29. SINPO: 44444 2015-05-18

9925 Khz Phillipines R. Philipinas 19:18 UTC This transmission is supposed to be English but sounds more like Spanish. ID several times between 19:18 and 19:19, followed by music. SINPO: 33333 2015-05-18

9940 Khz Swaziland TWR 19:29 UTC Only just audible through noise. List show language to be Lingala SINPO: 32222 2015-05-18

6070 Khz Germany CFRX 21:25 UTC English. ‘The Shortwave Hangout’. CFRX live via channel 292. SINPO: 54444 2015-05-24

9310 Khz Thailand VOA Deewa Radio 18:18 UTC Pashto. Male announcer with female singing guest. SINPO: 43333 2015-05-25

11660 Khz Armenia BBC 18:57 UTC Kinyarwanda. Male announcer. Sign off at 19:00 SINPO: 43333 2015-05-25

4835 Khz Australia ABC Alice Springs 19:58 UTC English. news at 20:00. Fading out at 20:05 down to 22222 SINPO: 32233 2015-05-25

6035 Khz Sao Tome VOA 20:51 UTC Hausa. Male announcer SINPO: 33333 2015-05-25

6080 Khz Botswana VOA 21:00 UTC English. ID followed by News. Some ACI from CRI SINPO: 43344 2015-05-25

6115 Khz Phillipines R.Veritas Asia 21:05 UTC Chinese. Male and female announcers. Some QSB SINPO: 43344 2015-05-25

6190 Khz China CNR2 21:14 UTC Chinese. female announcer. SINPO: 32233 2015-05-25

6200 Khz Tibet PBS Xizang 21:18 UTC Modern dance music. SINPO: 43344 2015-05-25

4915 Khz Brazil R. Dacqui. 21:22 UTC This is an assumption for R. Dacqui. Music and chat but unable to tell the language. Very heavy QSB and v. poor signal. Listened until 21:40, but still couldn’t get positive ID. SINPO: 21112 2015-05-27

5960 Khz Albania CRI 21:58 UTC English. Chinese lessons. Coming in like a local FM station SINPO: 55455 2015-05-27

6850 Khz Pirate R. Tidalwave 23:10 UTC Eclectic Pop music from all ages. SINPO: 54444 2015-05-27

15105 Khz Ascension Island BBCWS 19:39 UTC Hausa. Discussion program SINPO: 43333 2015-05-31

15480 Khz Madagascar AWR 19:53 UTC Arabic. Music and chat SINPO: 42233 2015-05-31

13580 Khz Bangladesh Bangladesh Batar 19:59 UTC English. Just caught the sign-off SINPO: 44444 2015-05-31

Some logs from today, Monday 25th May

I finally managed to get some listening time in! Over the last few days I have been putting together a pre-selector from a circuit and plans on the Bavarian DX Club website. It is in German but the circuit and coil winding info are easy to follow. The Tesun PL-600 that I use suffers from overloading and image interference when coupled to an external antenna. This pre-selector has eliminated that, and the tuning is nice and sharp. This evening I finally managed to here ABC Alice Springs on 4835 Khz by being able to peak up the pre-selector for that frequency. The signal didn’t last long, only about 5 minutes, but enough time to confirm that it was this station. I shall devote another post to the pre-selector another day, but suffice to say it is now a permanent fixture at this listening post.

Logs from today:

9310 Khz Thailand VOA Deewa Radio 18:18 UTC Pashto. Male announcer with female singing guest. SINPO: 43333 2015-05-25

11660 Khz Armenia BBC 18:57 UTC Kinyarwanda. Male announcer. Sign off at 19:00 SINPO: 43333 2015-05-25

4835 Khz Australia ABC Alice Springs 19:58 UTC English. news at 20:00. Fading out at 20:05 down to 22222 SINPO: 32233 2015-05-25

6035 Khz Sao Tome VOA 20:51 UTC Hausa. Male announcer SINPO: 33333 2015-05-25

6080 Khz Botswana VOA 21:00 UTC English. ID followed by News. Some ACI from CRI SINPO: 43344 2015-05-25

6115 Khz Phillipines R.Veritas Asia 21:05 UTC Chinese. Male and female announcers. Some QSB SINPO: 43344 2015-05-25

6190 Khz China CNR2 21:14 UTC Chinese. female announcer. SINPO: 32233 2015-05-25

6200 Khz Tibet PBS Xizang 21:18 UTC Modern dance music. SINPO: 43344 2015-05-25

SO239 to 3.5mm converter

In a previous post (July 31st) I mentioned I had put together an SO239 to 3.5mm converter so that I could hook up my outside antenna to the Tecsun PL-600. The antenna connector on the 600 is a mono 3.5mm jack plug.

I had seen these converters for sale but I decided to luck through the junk box and see what I could come up with. What I ended up with was the following:

A short piece of 15mm plastic conduit, a plastic cable gland which was a snug fit in the conduit,  an SO239 socket with a large centre nut rather than a bulkhead type, and a length of RG214.

It was then a simple matter to glue the SO239 into one of the conduit. I used 2-pack resin adhesive for this (Araldite in the UK). But prior to this, I prepared and soldered one end of the RG214 to the socket. I left the adhesive to set fully over night, then fed the cable through the plastic gland. I slid the gland up to the conduit, but not quite in, and covered both the gland threads and the inside of the conduit with 2-pack. I pushed the gland into the conduit and again, left it over night to fully adhere. Following this, the cable gland was pinched up tight onto the cable, and the other end of the cable soldered to the 3.5mm plug. RG-214 is a snug fit in the shell of a 3.5mm plug. This completes the construction. You can also add some heat-shrink tubing to the whole, which I was going to do, but didn’t get round to. The following images show the finished article. Does it work? – yes very well, and whats more its all from the junk box!