Category Archives: Radio Modifications

Portables, SDRs, dongles, kits, and a spy radio: our virtual radio challenge responses

TristanDaCuna-001

Two weeks ago, I posted a virtual challenge for SWLing Post readers:  I asked you to imagine you were placed on a one-year research assignment on one of the world’s most remote inhabited islands, namely, Tristan Da Cunha, in the South Atlantic.

Your goal was to assemble the best shortwave listening set-up possible for your virtual budget of $200 US. You were tasked to track down a radio kit that would keep you in touch with the world, and potentially afford you some very unique DX. [If you haven’t read the full virtual radio challenge, including all of the limitations you might face, I encourage you to check out this post before continuing.]

Your Reader Responses

And, wow, what great responses–!  First, I want to thank all who participated in this challenge. No two responses were identical.  Some truly surprised me…I must say, I sincerely hope you enjoyed this exercise as much as I enjoyed reading what you’ve sent to the SWLing Post!  

Below you will find ten responses from readers, representing remarkable diversity in radio set-ups. Note that my comments follow; they are italicized and in bold.

Now, with no further ado…I welcome you to radio DX on Tristan de Cunha!


from Frank Holden

TecsunPL-660First up, Frank Holden, who submitted his entry at 3:00 AM–prior to leaving on a 6:40 AM flight. Obviously, travel was on this Post reader’s mind.

Frank writes:

Based on both my own experience and recent swling.com research I would choose a:

(Photo courtesy of http://www.perite.com/)

Squidpole Antenna (Photo courtesy of http://www.perite.com/)

Total is $210 Australian, so you will get change out of $200 US.

Some notes:

  • Feed antenna up inside the Squidpole and tape at the top…. The rubber ‘bobble’ is removeable.
  • Maybe run a short length of coax from radio to base of Squidpole.
  • Make sure the Squidpole is well stayed. My experience in VP8land and Tierra del Fuego is that the constant flexing in high winds will lead to squid pole failure. Mine were secured to the taffrail on my boat… i.e. at the base and 50cm up from base…. Failed at the 50 cm point. I have also had a 5 metre high quality (marine grade) alloy whip fail in the same manner.
  • Utilise rest of baggage allowance with warm clothes, rum (power outages… for use during), etc.

Thanks, Frank! I love the idea of the Squidpole as it can give you a little height when trees are absent. I have used a similar telescoping pole for Ham Radio QRP operations: a Jackite pole. I’ve broken the tip section twice already due to my own clumsiness–fortunately, the tip can be purchased separately. As you suggest, I bet the winds on Tristan Da Cunha would give the Squidpole a run for its money!


from AB3RU

The Ham It Up v1.2 - NooElec RF Upconverter  converts your RTL-SDR dongle into an HF receiver.

The Ham It Up v1.2 – NooElec RF Upconverter converts your RTL-SDR dongle into an HF receiver.

AB3RU writes:

I propose using my current setup, since a laptop is a freebie here. I use the following in my setup:

1) RTL-SDR dongle for the laptop ($15)
2) Ham it up upconverter ($40)
3) AlphaDelta SWL sloper, MFJ 1020B (eBay, got ‘em for $102)

That’s $157. That leaves $43 for a 25? length of coax and two MCX adapters. Coax run is $15 (at $0.39/ft for RG-8X.) I forgot how much the adapters were, but less than the $28 left over after buying the coax run.

Downside? I have no pole to support this, and houses on the island are only one story structures. I’ll have to attach the high end of the sloper to the peak of the home where I’m staying, and I’m sure that height is less than the 25? recommended by AlphaDelta. In addition, I’ll have to plant a stake at the lower end of the sloper to keep that end the recommended 8? above ground. I also made no provision for extra power if a power outage exceeded the amount of juice in my laptop battery.

If push came to shove, I would drop the MFJ 1020B for an extra $50 to buy supports or an extra battery.

Thanks, AB3RU! I’m willing to bet that you might find something on the island to support one end of your sloping antenna. It might be a challenge to meet the 25′ recommended height, as you stated. Still, this is an innovative and quite portable option!


from Tudor

Sony-ICF-SW7600GR“Tudor” comments:

Here are my choices:

  • A 50-100m wire to be used as an antenna for SW and MW. I imagine I’ll be able to catch a few MW stations from South America or Africa. As for choosing a radio…
  • I’ll need a good radio which allows using an external antenna not only for SW (all of them do) but also for MW (few of them do). I think there is only one radio which fits this requirement within the budget: the Sony ICF-SW7600GR, available on Amazon.com at prices around $140. My other choice would be a Sangean ATS-909X which works very well with external antennas, but it’s more expensive.
  • I’ll also need two packs of 4 AA rechargeable batteries and a charger.

Thanks, Tudor! I believe your choice of the Sony ICF-SW7600GR is a very good one, as the Sony is a solid performer. It would be a challenge to find a new Sangean ATS-909X within your $200 budget–you would need to track down a used one, most likely. With the PL-660 in tow, you would then have a full $60 to purchase batteries, charger, and your antenna wire. Very workable!


from KK6AYC

KK6AYC suggests using the MFJ Model MFJ-8100:

MFJ-Model-MFJ-8100

http://www.mfjenterprises.com/Product.php?productid=MFJ-8100W

It is through hole soldered so replacing parts is easy. Bring a bag of spare parts and a couple batteries. Get two headphones so that you and a friend can listen at the same time.

Thanks, KK6AYC! At $110 US, you would certainly have enough budget for spare parts, batteries, and antenna wire. While a regen receiver may not be for everyone, these do provide excellent sensitivity once you pass this rig’s learning curve for tuning. If the winds blow your external antenna around, you might have to ride that regen control! Great alternative to the typical portable–!


from John Treager

Next, John Treager, who writes:

Neat thought experiment! I’ve recently got back into SW listening after years away. I’ve been hitting your sites for two or three months and your weak station comparison really grabbed my attention but this one has lit the fire again.

[…]I’m a contract engineer who lives away from my primary residence most of the time so this challenge kind of strikes a chord. And, as I’m getting back into SWL, you’ve given me a reason to research (something engineers love to do!).

TecsunPL-660-SilverBased on the weak station article and discussion, I like what I’ve seen in the Tecsun PL-660 (although I don’t own it yet). […]Found in silver on eBay for $100.99 from kaito-electronics-inc. Seriously, what’s the fascination with black? Black is $20 more…

If I’m renting a room with a family on the island, headphones are a must. I’m cheap and traveling light so let’s go with Sony MDRZX100 headphones. I’ve used them for quite a while and like them. I find them comfortable for at least a couple of hours. Currently $15.09 on Amazon.

I enjoy the challenge of simplicity so, as far as an antenna goes, I would choose a simple long wire. Either a reel or one I build, $10-15. I get as much enjoyment from fussing with antennas as I do from turning knobs and dials. If my simple wire antenna doesn’t work when I get on location, then investigating and tinkering with antenna design and construction will fill the hours!

wrth-2014By the rules of the challenge, power is available but somewhat unreliable it sounds like. To meet that, I’m going with rechargeable batteries and enough to last for a while. AmazonBasics AA NiMH Rechargeable batteries (16 pack, 2000 mAh). Not the newest version, but should suffice for one year and 16 batteries should be enough for extended periods of no power. And, this may be a bit of a cheat, but I use AA batteries for everything, so I already have a charger!
Next, some sort of reference. I usually use either my laptop or a phone/tablet for frequencies/times from various sources, but given that there is no internet access in the residence and power may be occasionally spotty, let’s go with the World Radio/TV Handbook as a backup (I do miss Passport to World Band Radio!). I found WRTH on eBay (new, 2014 edition) for $27.24.

I assume I will have notebooks and pens for other reasons, so not included in the total.

So, all told…

Total: $182.67

With the remaining difference, I may get a Kaito KA321, which I have found to be a great deal of fun. […]Being a budget DXer, and given the performance of this little radio, I would almost have to have one along. I would love to see what it did in the South Atlantic!

Thanks, John! That should be enough AA batteries to keep you going well over a week with no power. Packing a WRTH makes a lot of sense. Via the island’s library Internet–however variable–you could download WRTH updates, as well.


from London Shortwave

The Global AT-2000 (Photo: RadioPics.com)

The Global AT-2000 (Photo: RadioPics.com)

London Shortwave sent his suggestion in by tweet–a simple, proven combo: 

Thanks, London Shortwave!  While the Global AT-2000 is a little difficult to find these days, London Shortwave has had excellent success with this antenna coupler. There should be enough room in his budget for rechargeable batteries, as well.  


from Princehifi

“Princehifi” comments:

If a laptop was coming along, I would have to use an SDR.

AFEDRI_SDR-USB-HS_640

I would get the Afedri SDR USB-only model [see AFEDRI SDR-USB-HS above] for $159 (board only, I’d have to mount it in a sardine can). I would then use the remaining $41 for a cheap used antenna tuner and a random wire for an antenna. I think this kit would make for an excellent listening post.

Backup power would be a concern with the outages, so I am contemplating a 6-volt battery backup power system to power my Phillips 4-port USB hub (6 volt DC in requirement). From there the USB-hub will power/charge a Dell Venue 8 Pro tablet (the laptop), the Afedri SDR and maybe a USB-powered speaker? Would have to test out this backup power scheme before boarding the boat!

I think I could do all of the above for $250 including the backup power system. Although it would likely push $300 when wires, cables etc are all in (does not include the tablet/laptop).

Thanks, Princehifi! So you’re a little over the $200 budget with all of the accessories, but if you already have a laptop and tablet, I think you could tweak your set-up to meet the budget goal. I did not realize that there was a USB only version of the Afedri SDR–I might have to get one of those myself!


from Rob

TecsunPL-660-SilverRob comments:

Here’s my list. Where can’t get it locally and I don’t have a firm shipping cost, I’ve estimated it as an additional 20%. Stuff I can get locally (Radio Shack, etc.) I haven’t added any shipping or sales tax.

  • Tecsun PL660 (eBay/Anon Co): $85 + $16 shipping = $101
  • 100′ roll of 22 gauge stranded copper wire (Amazon): $9.41 + 20% = $11 (good long random wire)
  • 25′ RG58 (Universal Radio price $0.25/ft): $6 + 20% = $7 (use the coax to get wire antenna out and away from the house; wrap it on an old jar (free!) to make an ugly balun to keep household noise from creeping up the outside of the shield)
  • 1/8″ phono plugs for antenna port (Radio Shack): $3.50
  • Koss Earbuds (Radio Shack): $5 (these really cut down on battery drain and make for a better house guest)
  • Eneloop charger & 4xAA batt combo (Battery Junction): $16 + 20% = $19.20 (the 660 comes with one set of AA’s, this gives another and an away-from-radio charger to cut down on noise)

TecsunAN200OK, that totals to $147 for the basics. Now I want to add two more things:

(That’s right, a spare radio. Because middle of nowhere.)

Grand total: $192

Now if I’m allowed to scrounge in the parts bin for stuff like 22 gauge antenna wire, RG58, and earbuds, there might be enough left over for a SECOND spare radio and 4 more Eneloops!

Thanks, Rob–you have a plan, indeed! Well thought through! I, too, would be very curious what sort of medium wave DX I could hear in the South Atlantic, especially since you know there would be no local blow-torch stations around. I have the Grundig version of the Tecsun AN200 and find it an essential antenna for portable MW DXing.


from Michael C. Fortner

ECSS-PL-660Michael C. Fortner’s list includes:

Radio: Tecsun PL-600 (I have one and am comfortable with it’s operation) – $43.35

Antenna: 500′ spool red 18 gauge wire (you can’t have too much wire in case of wind damage, animals, people, etc.) – $29.07

2 two packs of 1/8 mono phone jacks (again, backups are good) – $4.49 x 2 = $8.98

AmazonBasicsBatteriesBox-001Batteries: 16 AA NiMH batteries – $25.86

Charger: Solar battery charger (backup to mains power that charges batteries in radio): $19.99

Headphones: Koss KSC-75 headphones x2 (good dynamic range for the price and I have two pair that I use): $14.82 x 2 = $29.64

Grand total: $156.89 (all qualify for free shipping)

I’d guess I would save the rest for repair costs in case the radio acts up. Of course, I’d take the one I already have as a spare. When in remote locations, backups are essential so I probably bought more than most people think I need. And as far as the battery charger, rapid chargers are bad for most NiMH batteries so I went with a slower charger. And don’t forget that the Tecsun can charge the batteries in the radio when not in use.

Thanks, Michael! You are erring on the side of having extra batteries and more than enough wire for antennas; there’s no way you’ll run out in your one-year stay. On Tristan, I know that locals often trade supplies: those extra batteries may turn into an antenna support!    


from Kenny B

 OLYMPUS DIGITAL CAMERAKenny B writes:

I love your site, I’m there everyday and almost forgot to enter so here it is:

1. Kaito 1102, I have had good luck with it and it has ssb, second choice would be a Tecsun PL-380, I really love this radio and it’s a great little dxing machine but no ssb.
The Kaito is 64.95 on Amazon, free shipping.

The Sundance Solar DIY battery charger

The Sundance Solar DIY battery charger

2. A Sundance Solar- build it yourself battery charger for AA and AAAs: $40.00 plus 9.99 shipping

3. Scotts Electronics 384pf air variable capacitor, $13.95 plus $4.95 shipping, this if for my shortwave magnetic loop I will build, I’m pretty sure I can procure the wood for crossbeams or something to make a loop can be had on the island.

4. 6ft RG-58, Wal-Mart, $4.95

5. 50ft speaker wire, Home Depot, split it gives me 100ft, can also be used to make a dipole or longwire, $9.99

6. Sanyo Eneloop rechargeable batteriess, AA, 3rd generation, 2000mah, 8 pack $26.40, Amazon, free shipping

7. Travelproducts.com, 1600 watt voltage converter, 19.99, free shipping

8. Radio Shack 1/8th inch miniplug for end of coax, $4.00

Wow! Thanks, Kenny B! Other than the KA1102, your complete kit is DIY–I like it! You could build the battery charger and antenna prior to leaving. 


from Anil

Anil writes:

1. Receiver: Wandel & Goltermann FE-8 Spy Radio Receiver (US$ 120 at a Hamfest)

Wandel_And_Goltermann_FE-8

Wandel & Goltermann FE-8 Spy Radio Receiver from the cold war (mine was manufactured in 1963. I bought it at a Hamfest in Sweden a month ago for the equivalent of US$ 120.[…]

For ruggedness there is nothing else like it. It is completely sealed and constructed from a single piece of die-cast machined aluminium and stainless steel. Just the thing for wet and rainy Atlantic islands! Covers 2.5 – 24 MHz and only needs 6 Volts at 8mA. A pack of twelve AAs will fit in my pocket and last at least a year with about three hours of listening every day. No adapter, no charger. The razor sharp 3.1 kHz Collins Mechanical Filter is not ideal for music but hard to beat for general news and SSB utility listening. Like the famous Collins R390 it uses a mechanical “digital” dial accurate to 1 kHz which also glows in the dark. […]It is smaller that a Tecsun 660 though it weighs a lot more. More about this radio here http://www.cryptomuseum.com/spy/sp15/fe8.htm

2. Antenna & Earth (US$ 15 in any electrical store)

Random length PVC insulated wires with a banana plugs- total 50 meters. The radio has a hi-impedance input and is sensitive enough to do a great job with just 20 m of wire. The rest is spare.

3. Headphones (US$ 25 on eBay)

Lightweight Telex Aviation Headset with 1500 Ohms impedance can be worn for long periods with no fatigue. The audio response is tailored for voice.

WandelAndGoltermann-FE-8-Front

4. The latest  WRTH Handbook (US$ 30 online)

I’m all set for the trip now with $10 to spend on a supply of chewing gum. I know that this radio setup can easily deal with whatever is thrown at it… the question is if I can!

Thanks, Anil!  Wow…I never saw that spy radio coming! It does look like an ideal radio for prolonged use and for pretty much any environmental conditions. I hope you realize that I will be bugging you (okay, pun intended!) to provide us with a few broadcast recordings from the FE-8. It’s certainly got my interest piqued!


Now, that was fun! Thank you all…

I know this sort of challenge may not appeal to everyone, but I really enjoy it. This sort of exercise forces you (though safely) outside the comfort-zone of a home radio set-up. Your responses are truly innovative. I only wish the Post could actually send our participants to Tristan de Cunha to try their set-ups out first-hand! I, for one, would love to come along…

Thanks, again, for your participation! If your response wasn’t included above, or I didn’t respond to you directly, please let me know: it’s possible I skipped over yours by mistake as there were quite a few responses to collate, and my email is managed by a rather discriminating SPAM filter.

Meanwhile, if you think of an alternative set-up–or would like to add your own to this post–please comment below!

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Hidden feature: Calibrating the Tecsun PL-880 for zero-beat operation

Tecsun-SSB-QRG-1Many thanks to Dan who learned, via the Tecsun PL-880 group, of another way to calibrate the PL-880 in upper and lower sideband. This method seems to be a little easier than a previously posted procedure.

Anna, with Anon-Co, translates this procedure given to her by Tecsun technicians:

  1. Place the Tecsun PL-880 in LSB or USB mode
  2. Tune to an AM broadcast station and zero-beat the signal (fine tune it until the signal has no SSB distortion and voices/music sound natural)
  3. If the last two digits of the frequency are not “00”, this means there is some display deviation
  4. Simply press and hold the [SNOOZE] button for about one second or so to calibrate the last two frequency digits, which will show “00” when successful.

I will try this procedure later today by re-calibrating my PL-880.

Dan has also noted what many others have–that the PL-880 “is sensitive to both power levels, and time in the powered on state, and will vary by some hz up and down the bands
no matter what one does to zero at any particular point.”

Has anyone else experienced this?

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My Raspberry Pirate is now radio-active

RaspberryPirateRadio

Two weeks ago, Make Magazine published a simple hack that turns your Raspberry Pi
into a low-powered and portable FM transmitter/radio station.

For those of you not familiar, the Raspberry Pi is a single-board computer developed in the UK by the Raspberry Pi Foundation. The RasPi is a cleverly-designed, useful device–especially if you like tinkering with mobile computing. Best yet, the Raspberry Pi is very inexpensive; the basic computer costs a mere $40 US, though there are starter kits that include common accessories for $70-80.

One of the first things I did upon returning home, following nearly two weeks of US east-coast travel (which included the Winter SWL Fest), was to build my own Rasberry Pirate Radio. I had hoped to make the radio before my trip, but thought I wouldn’t have enough time. Had I known what I know now–that the Raspberry Pirate Radio is a super simple and easy hack–I would have made it anyhow and taken it along for the ride.

My antenna wire connected to pin 4. (Click to enlarge)

My antenna wire connected to pin 4. (Click to enlarge)

To be fair, what makes this project so simple is the fact that Make Magazine so beautifully documents the procedure on their website.  It also helped that I have a little familiarity with creating disk images–still, I’m certain that if I were a total newbie, I could have done all of this within 30 minutes…Which is just what I did.  And I’ll bet you can, too.

There are really only three steps required to make your own Raspberry Pirate Radio:

  1. Make a simple FM antenna and attach it to pin 4 on the Pi’s board. In my case, I had a small dual conductor connector attached to about eight inches of twisted pair wire. I simply connected one side of this connector to pin 4. Since my FM antenna is not cut to a resonant length, I know I’m compromising the FM transmitter’s range a bit…Still, it’s what I had on hand, and it works!
  2. Download Make Labs‘ disk image and flash it to your SD Card.
  3. Add music to the “Pirate Radio” partition of the SD card and edit the config file to your preferences. If you have the option to do this step on Mac OSX or Linux, the process is much easier than on Windows. But Windows users, fear not: Make Magazine describes, in detail, how to add files.

After I finished these steps, I simply plugged in my Raspberry Pi and tuned one of my radios to 89.9 MHz (the frequency I chose and saved to the config file). The Pi booted and started the Raspberry Pirate Radio script automatically.  Brilliant!

RaspberryPirate-FMRadio

It’s alive!

Being a shortwave radio nut, of course I loaded my Raspberry Pirate Radio with a few gigabytes of my off-air recordings that are a heavy on music (all of which you, too, can pull from our Shortwave Radio Audio Archive). It’s kind of fun tuning my bedside Tivoli Audio Model One to 89.9 MHz and hearing the Voice of Greece, with all of its shortwave audio characteristics. If I close my eyes, I can pretend the Model One has a shortwave band. Love it!  Just the thing to drift off to…

I’ve kept the Raspberry Pirate Radio running nearly 24/7 here at home. I’ve also had excellent luck running the radio mobile by using my Eton Rechargeable Battery Pack as the power source (Universal Radio also sells a higher capacity version, if you like). I’ve yet to test how long the power block will run the Raspberry Pi, but I imagine it will last for a couple of hours, at least.

RaspberryPirate-EtonBlock

If you want to take your Raspberry Pirate Radio in the car, it’s a simple matter to power it with a 5VDC USB power plug. You probably already have what you need, especially if you charge your mobile phone in the car.

If you’ve never experimented with the Raspberry Pi, this is a perfect first project for you. Just think about it: for under $50, you can make a simple-yet-effective FM radio station which shuffles your favorite music or recordings from any source–from obscure radio pirates to far more distant stations. Besides, once you have a Raspberry Pi, you’ll find there are thousands of other radio projects to occupy your rainy weekends.  Enjoy!

Many thanks to Make Magazine for posting this simple project!

Update: Several people have written concerned that the Raspberry Pirate Radio has no output filtering of its RF signal.  This is true. Though I have not tested it, I would have to assume that it could radiate on harmonic frequencies and potentially interfere with other radios. Though the broadcast footprint is very small, if you live in a high-density neighborhood, you will need to keep this in mind. I live in a very rural area and my nearest neighbor couldn’t possibly hear my Raspberry Pirate Radio.

I’m very curious if there’s a simple mod to filter the output RF. If you can think of one, please comment!

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Repairing the Tecsun PL-600 after electrostatic discharge (ESD)

SWLing Post reader, Michael Taniwha (NZ1MT), has kindly documented how he repaired his Tecsun PL-600 after it went silent on the shortwave bands. If this has happens to you, don’t toss your PL-600, use Mike’s excellent guide below for an inexpensive repair.
(Click on images to enlarge)


TECSUN PL-600 – Electrostatic Discharge Repair
Tecsun-PL600

My TECSUN PL-600 had been a trusty bedside radio companion for the last two years. The radio is also my alarm clock and I use the timers to wake me up each morning to my local AM station WHYN or Radio Australia on SW.

On November 29, 2013 I turned the TECSUN PL-600 on and attempted to tune into some SW stations and was surprised to find the radio stone deaf on all the SW bands….similar to the Steely Dan song FM (No Static At All) except in this case it was SW (No Static At All). Immediately my first thought was that the radio had probably suffered an Electrostatic Discharge (ESD) when I had touched the external antenna while moving it around earlier in the day. I reset the radio and tested all the bands, AM and FM bands seemed to be working OK, yet SW remained dead.

My next step was to open up the radio and look for the obvious.

IMGP0092

Upon opening the radio I was surprised to see two back-to-back IN4148 diodes (D17 & D18) fitted across the external antenna input to ground and that the diode D17 was cracked in half. The back-to-back diodes offer a very high resistance at the micro-volt RF level, but will conduct once the forward voltage (Vf) raises above 1.0V. So for the cost of a few pennies we have a relatively cheap and dirty ESD protection circuit.

IMGP0095

My first thought on the cause of the cracked diode was a manufacturing defect when the diode was soldered in at the factory (in fact I later discovered it was likely broken during assembly of the rear cover at the factory – read on). My next thought was just my luck that the broken diode was probably in the polarity direction that I needed the ESD protection.

The next step was to locate a schematic diagram and start circuit tracing to find the likely blown front-end RF pre-amplifier FET/MOSFET that had been damaged. As luck would have it a schematic of sorts is posted in the TECSUN PL-660/PL-600 Yahoo Groups. See the following Link.
http://groups.yahoo.com/neo/groups/TecsunPL660TecsunPL600/files/PL%20600%20Schematics/

The only issue is the text is mostly in Chinese! However, the parts on the radio PC board are clearly labeled as are the parts on the schematic.

IMGP0109 schem

What I quickly notice is that the schematic shows no ESD protection on the front end (upper highlighted circle), but in fact the radio has additional parts D17and D18 (the back-to-back diodes), and C57 on the PC board coming from the external antenna jack. Whenever the external antenna jack is used the jack disconnects the radios telescopic antenna which is connected to C68 to the antenna jack switch circuit. After this antenna switch the schematic from C126 onwards is correct. Following the schematic we see that both the telescopic antenna and the external antenna go through the DX/NORM/LOCAL antenna switch to the IQ3 (AGC?) transistor and then to the RF pre-amp 2Q1 FET (lower highlighted circle). My educated guess was that the 2Q1 FET type 2SK2394 was damaged by the ESD. Yes the 2Q1 it is a very small SMD type FET.

IMGP0097

My reasoning for the 2Q1 having failed is that FM reception was not affected as the antenna circuit goes directly to the TA75358AP FM decoder chip IC1.

SchematicPL-600

Similarly, AM reception was not affected as the AM signal is primarily from the ferret bar AM ANT coil that uses the 1Q1 FET for RF pre-amplification.

PL-600 Scem2

At this stage I contacted Kaito Electronics Inc. the official US based distributor of TECSUN radios and inquired if they provide component level repairs or provide replacement SMD components. The answer was no to both questions.

I then started hunting around online to locate a replacement 2SK2394 FET which is a Sanyo manufactured FET and finally found one for sale on eBay from hkutsource (Hong Kong UT Source) for $2 + $4 shipping. See following eBay link.

http://www.ebay.com/itm/2SK2394-7-Manu-SANYO-Encapsulation-SOT-23-High-Speed-High-Current-Switching-/130835554230?ssPageName=ADME:L:OU:US:1120

This FET is listed as a 2SK2394-7 but all the specifications line up against the specifications for a 2SK2394. I ordered it on December 6th and it arrived 10 days later enclosed in an ESD bag and packaged in a sturdy little box.

IMGP0116

IMGP0117

IMGP0118

Now the fun starts. To replace the 2Q1 SMD FET I used my needle nosed 40W soldering iron, vacuum pump solder remover and wore my ESD strap to stay grounded. First step was to remove the existing 2Q1 FET.

IMGP0119

Next step was to install the replacement 2Q1, if you haven’t worked with SMD devices before let’s just say it is like working with a live insect, they are small and seem to move around on their own accord.

After much tooth pick (my hi-tech SMD tool) maneuvering I finally had it installed. OK I admit it is a little skewed. Have you noticed I have also installed a replacement D17 diode at the top right of the picture?

IMGP0122

The moment of truth! At this stage I did a quick radio check and fired up the PL-600 on the SW band and tuned into CHU, the Canadian Time Station on 3330 kHz, and picked up a time pip signal. In addition I was tuning into other SW stations and had plenty of static as well.

I now decided to install additional ESD protection on the telescopic antenna input as well using two IN4148 back-to-back diodes. After a quick hunt around in my junk box I located an old PC board with a few IN4148 diodes attached. Quickly removed and tested them using my multimeter diode checker.

IMGP0112

IMGP0111

I then installed the additional ESD diodes as shown below (the ATN label on the PC board is where the antenna wire from the telescopic antenna on the back over is attached).

IMGP0124

Finally it was time to reassemble the radio. This is when I started having real problems as the rear cover just would not reattach. When I looked closely I could see that the plastic support screw hole on the rear cover for the telescopic antenna sits partially against the PC board where the D17 diode is located. Now that explains why that diode was cracked when I first opened up the radio at the beginning of this repair. It appears the two ESD diodes were probably a design afterthought and the rear case wasn’t adjusted to accommodate their location on the PC board.

IMGP0125

To get around this issue I removed the replacement D17 and relocated it to the lower part of the PC board below C57. Once I had moved D17 I could now reassemble the radio and again tested the radio. My TECSUN PL-600 is now back to its trusty role beside my bed and picking up SW stations.

Mike-Tecsun-PL-600-Repaired

In summary if you have a TECSUN PL-600 or PL-660 that is deaf on the SW band it is likely to be an ESD damaged 2Q1 RF pre-amplifier 2SK2394 FET. For $6 and some time and effort you can replace the FET and have your radio back up and running like new.

Michael Taniwha – NZ1MT
Email: To send Michael an email, simply insert his callsign @YMAIL.COM
December 17, 2013


Many thanks, Mike, for the excellent documentation and detailed photos! 

Note that you can also download Mike’s guide as a PDF on the Tecsun PL-660/600 Yahoo Group (membership required).

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Tecsun PL-880: How to fix the audio level problem

photo (5)As more and more people are beginning to receive their Tecsun PL-880s, I’m receiving emails and noticing comments regarding an “audio level problem.”

Here’s the symptom: when you tune your brand new PL-880 to a relatively weak station on AM or shortwave, the audio level jumps from low to high in what seems like a random pattern.  It’s very annoying. Like me, many assume they have received a faulty unit–some have even sent their new PL-880 back for refund.

In reality, the PL-880 is simply following a default muting threshold level and the audio is responding accordingly. Fortunately, there’s an easy fix for this–you won’t find it in your owner’s manual, but you will find it in one of the first PL-880 posts I published:

Hidden feature: Adjusting the Tecsun PL-880 muting threshold

I hope Tecsun will start shipping their PL-880s with the threshold set to “00” or off.  It would certainly lead to less confusion and frustration.

You can follow all Tecsun PL-880 updates by bookmarking/checking this link.

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Jeff designs an SDR “Go Kit” around the Softrock Ensemble

SoftrockGoKit1Jeffrey Fritz (WB1AAL) contacted me with details about his SDR (Software Defined Radio) “Go Kit” and has kindly allowed me to post it.

Jeff writes:

As a reader of the SWLing blog, I know that you are very interested in SDR. And you probably know that a “Go Kit” is a portable ham radio system in a case that can be moved at a moment’s notice and set up at another moment’s notice virtually anywhere.

I have a VHF Go Kit made up for emergency events. It is complete with waterproof carrying case, Aden PCS-7000H two-meter transceiver, a Kenwood VHF tuner, a Kenwood SW-100 VHF SWR bridge and two antennas (a 2-meter J-pole made out of twin lead and a two meter mag mount.) But what if there is a need to monitor the HF bands during the same event?

Now that I own a Flex-1500 SDR transceiver, the Softrock Ensemble SDR receiver that I bought a while ago has become somewhat redundant. It is still a serviceable radio and works fine, but it can’t hold a candle to the amazing Flex-1500. While I could turn it into a panadapter or sell it on eBay, eHam, etc., I had a better idea.

To monitor the HF ham bands, I could use something like my Grundig G3 shortwave radio in my Go Kit. While it is portable, battery operated and will tune LSB and USB, listening to SSB or even CW in an emergency situation with the G3 can be a bit of a chore. (Think of the old boat anchors with their main tuning and fine tuning band spread dials, but now make both dials tiny and you’ll get the idea.) Instead, why not build a 12-volt battery supply with common, easy to obtain batteries? I could connect it to the Softrock Ensemble and then via a USB audio interface to a battery powered laptop. Add a pair of headphones and we are in business.

That is just what I’ve done.

I’ve attached some photos of my most recent project–done this past weekend actually. [Check out photos above and below] It’s an SDR Go Kit. One of the attached photos shows the laptop and the Softrock Ensemble SDR receiving 40-meter band SSB while entirely being operated on battery power. There is no power switch. You simply pull the DC jack out of the Softrock Ensemble SDR radio when it isn’t in use. Simple as it gets! The other photo shows the battery pack built into a (ahem!) Preparation H Pad holder pack. (Now, I am not saying who used this!)

Ah but what will battery life be like with 8 C cells in series driving the receiver? It’s too soon to say because I just put it together an hour ago. But here’s a guess:

SoftrockGoKit2The Softrock Ensemble draws 18 mA at 12.6 volts (my measurement.) An Alkaline ‘C’ battery can supply up to 8,000 mAh, so doing some math and assuming fresh batteries, the battery pack should run the radio for roughly 400 hours. (Hopefully my math is correct!) If so, then I think that the laptop batteries will give out long before the life span of the C Cell is reached!

73,

Jeff, WB1AAL

Jeff, this is an excellent use for the Softrock Ensemble. I imagine it will run for a very long time drawing only 18 mA. I have a “Go Kit” for QRP ham radio purposes and one for SWLing during travels. You’ve inspired me to piece together a proper receiver “Go Kit” to be used in case of emergencies.

Readers: If you have a project, like Jeff, that you’d like to share on the SWLing Post, feel free to contact me with details!

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Using the RTL2832U $20 SDR for HF & trunk-tracker scanning?

DE_DVB_T_1In response to our post on inexpensive SDRs based on the RTL2832U, Jeff Benedict writes:

Here’s a website that has a lot of info on cheap SDR gear.  They have a write-up on an external board which adds HF capabilities.  I have one but haven’t done anything with it yet.

http://www.hamradioscience.com

Jeff  KB7AIL  CN88

Thanks, Jeff! Has anyone tried HF with any success? I’m curious how well this über-cheap receiver will cope with adjacent signals and blowtorch stations within the HF spectrum.

Meanwhile Neil, blogger on Fofio, commented:

I have an RTL-SDR system up and running.  I have done 2 demonstrations for my local Ham Radio club.  One on the basic setup and use of the dongle, using both SDR# and HDSDR.  The other presentation showed the remote receiver capability using a Raspberry Pi as the receiver with the dongle attached and a remote SDR# computer decoding the stream over a network connection.  Once I compensate for some minor frequency discrepancies it’s a pretty good receiver.  The only issue I have noticed with mine (one of the early E4000-based models) is a tendency to overload in the presence of a strong signal.  We have a pretty powerful 2 Meter repeater less than a 1/4 mile from our home, and when it’s active it causes some strange results with the RTL-SDR setup.

I have yet to try one of the HF converters they make for these.  I hope to do that soon.

Another project I was reading about today that I may try out is using 2 of the dongles at once to create a trunk-tracker scanner.

Wow! Two $20 USB SDRs and a little PC magic could yield a trunking scanner? I want to hear more about this. Trunking scanners tend to be both expensive and complicated. If a web-updated database could be downloaded and used to control this sort of rig, the possibilities would be most impressive!

Neil, keep us informed!

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