Tag Archives: Tecsun PL-680

Rolf’s PL-680 modification allows external antenna on LW and MW

The Tecsun PL-680

Many thanks to SWLing Post contributor, Rolf Snijder, who writes:

I did a modification today on the Tecsun PL-680 [which allows for an] external antenna on LW and MW.

The internal ferriet is also working, but on my active loop, MW and LW is now working !

So far away stations I can now receive on this portable radio.
It is only a560 pF capacitor added!

Click to enlarge.

Click to enlarge.

It works on LW and MW now with this mod.

FM is less now I think, maybe I will put it on a switch so I can turn it off.
And now also the ferrite is still working, so I hope to find a solution for that.

Many thanks for sharing your modification and photos, Rolf! Check out Rolf’s other PL-680 mod by clicking here.

Tecsun PL-680: Rolf touts enhanced performance using PL-660 mod

Many thanks to SWLing Post contributor, Rolf Snijder, who writes:

I have made the same modification to the Tecsun PL-680, that was done [by many on the] PL-660 earlier.

The PL-680 is now a great radio; I think now one of the best! I do not own a PL-660, so I cannot compare.

Photo detail

Overview of modification.

For disable soft mute you can see the 2 joints and you must scratch a path on the print near the switch. (same on a PL-660)

Closeup of joint #1 (click to enlarge)

Closeup of joint #2 (click to enlarge)

With the tone switch [on the left side panel of radio] you can turn the muting on and off. On FM I need to set it on for better results, but on LW MW and SW always off!

Frequency adjust is with the pot: adj1391 in the right corner. (for the 1 kHz off freq)

Click to enlarge.

Hope I can help someone with this on your great site.

Greetings,

Rolf Snijder
Netherlands

Many thanks for sharing this PL-680 mod, Rolf! This seems like a simple enough project and one that can be undone if you aren’t pleased with the results.

Post readers: Please comment if you’ve made this modification to your PL-680 or PL-660 or if you have other successful modifications to share!

Oxford Shortwave Log: DXing in the tropical rainforest of Pará, Brazil – part 2

img_9956pl-680

Hi there, here is part 2 of my reception videos taken in the tropical rainforest of Pará, Northern Brazil. As I mentioned in my previous post, I took a Tecsun PL-680 with me on the trip because I didn’t want to risk losing or trashing one of my precious vintage portables but also because of the following:

  • It can handle a longwire very well without overloading (I actually only used a 5 metre wire)
  • An excellent synchronous detection circuit and audio bandwidth filtering options
  • Excellent sensitivity, as demonstrated by the many DX reception videos on YouTube
  • If it got lost or damaged it would be a pain, but not difficult to replace

So, what can you hear in the jungle? Part 2 of my group of reception videos follow below – I hope you enjoy them.


Tropical rainforest DX in Pará, Brazil: RMI Overcomer Ministry 11530 kHz

 

Tropical rainforest DX in Pará, Brazil: Radio Tamazuj 11650 kHz, Madagascar

 

Tropical rainforest SW in Pará, Brazil: Radio Nacional Brasilia 11780 khz

 

Tropical rainforest DX in Pará, Brazil: R Aparecida 11855 khz (TX distance 2430 km)

 

Tropical rainforest SW in Pará, Brazil: R Brasil Central 11815 kHz, Goiania

 

Tropical rainforest DX in Pará, Brazil: Voice of Turkey 11980 kHz

 

Tropical rainforest DX in Pará, Brazil: Radio Dabanga 13800 kHz, Madagascar

 

Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.

Tecsun PL-680 Beats Expectations

 

I have been procrastinating over investing in another portable shortwave radio to replace my ageing (but still going strong) Sangean ATS909. Also known in the U.S. as the rebadged Radio Shack DX–398, the Sangean has been a most reliable rig for in-the-field DXpeditions. My unit is one of the early first generation versions that I purchased on the second-hand market, so I’m guessing it has to be at least 16 years old now. It continues to provide a full rich tone quality on AM/FM and is very sensitive on shortwave providing you use an external antenna of 5 metres (16 feet) or more. The radio received some bad press because of its poor SW reception using just the telescopic rod antenna, which frankly was justified. The in-built whip is useless! But all of my work has been with an external antenna, and the results have been most successful over the years.

But the old ATS909 has lived a hard life, having been bounced around in the car on rough dirt tracks, dropped a few times, and thanks to a recent home renovation project it now has paint splattered all over it. On one occasion, I’d even left it outside on the ground after a spot of gardening, subjecting it to half an hour of heavy rain, before realising my forgetfulness. The radio was soaked but still going strong when I picked it up. However, the digital readout was all messed up. After 24 hours of drying, and it fired up beautifully again, and has been fine ever since! That’s some impressive build quality there! Thanks Sangean!

Anyway, a few months ago I decided to “pull the trigger” and purchased a new Tecsun PL-680 AM/FM/SSB/Air Band radio. This rig has been on the market since around February 2015. So far, it has performed very well for me.

Interestingly, on the built-in telescopic antenna reception is only marginally better than the Sangean, but the Tecsun is really quite sensitive with an external long wire antenna. In fact, I’ve had it hooked up to my three double bazooka (coax) dipoles for 80, 40 and 20 meters, and the performance has been excellent. The tone quality is not quite a good as the Sangean, lacking richness and depth on MW, FM and SW. But for DXing, the audio appears just right for digging out clear audio from the noisy shortwave bands.

pl680-at-the-beach

Recently, I hooked up both portables for a side-by-side comparison using four different external antennas outside the shack with switches between the two radios. I was eager to check how they measured up in terms of sensitivity and selectivity. The results for the Tecsun were impressive, picking up all of the weaker signals that the Sangean could hear.

Indeed, on several shortwave broadcast bands, the Tecsun appeared to be just a touch more sensitive at digging out some of the weakest signals. The audio also appeared a little clearer for those weak signals, perhaps because it has a narrower audio response than the Sangean. And selectivity for the PL-680 was about the same as the ATS909, generally very good.

On the ham bands, however, the SSB audio quality of the ATS909 sounds more pleasant to my ears than the PL680. But the Sangean’s tuning process in SSB is somewhat more cumbersome than for the Tecsun.

The PL-680’s synchronous detector effectively reduces adjacent signal interference. It’s easy to use and is a strong feature in its favor. However, occasionally it can fail to lock on to a weaker signal or when the signal is subject to deep fading. One other characteristic of the Tecsun is that it has a rather overly generous S-meter, hitting S4 or 5 for all but the weakest signals. This is a meter not to be taken too seriously!

But the PL-680 is not without its faults!

Click here to continue reading the full story.

Rob Wagner, VK3BVW, is the author of this post and a regular contributor to the SWLing Post. He also blogs at the Mount Evelyn DX Report.

Mehdi discovers ESD protection in the Tecsun PL-680

The Tecsun PL-680

Many thanks to SWLing Post contributor, Mehdi, who writes:

Once you told me to be careful when attaching an external antenna to my portable radio.

Today I opened it to see whether it has some sort of protection on its external antenna path.

Tecsun-PL-680-Diodes

As you can see in the picture below, there are two diodes side by side (D4 and D2) which protect the radio’s front-end against high-voltage inputs.

Tecsun-PL-680-Diodes2

Description of what these two diodes do from http://www.giangrandi.ch/electronics/diode-clipper/diode-clipper.shtml:

“The basic idea of the diode clipper is that for signals with an amplitude within ±0.7 Vpeak (less than about +7 dBm over 50 ?) the diodes are just open circuits and do not interfere; for higher amplitudes, the diodes clip the signal to about ±0.7 Vpeak limiting the maximum power that reaches the receiver at about +10 dBm over 50 ?, which the vast majority of receiver circuits can easily tolerate. If you wonder why I specified +7 dBm for unclipped signals and +10 dBm for clipped ones of the same peak to peak amplitude, it’s because unclipped signals are supposed to have a nice sinusoidal shape; once clipped, they become more square and their RMS voltage is higher, explaining the 3 dB difference.”

Thanks for sharing this, Mehdi! I’m happy to see that the PL-680 has some built-in ESD protection.