Tag Archives: 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.

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

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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!

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

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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.

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Mehdi discovers ESD protection in the Tecsun PL-680

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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.

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.

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.

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Universal Radio: Used Tecsun PL-680 for $69.95

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I just noticed that Universal Radio is featuring the following used Tecsun PL-680 in their used receiver collection. Here’s the description:

The Tecsun PL-680 receives longwave, AM, FM and SW bands plus VHF Airband. It features a backlit digital display, stereo FM (to ear jack), SSB, clock timer, 2000 Memories, Sync. Detection, ATS and keypad entry. The left side features earphone, external antenna and input voltage jacks. The right side features a variable BFO and tuning knob. The rear panel has a battery compartment for 4 AA cells (not supplied). This PL-680 system includes: box, nice carry case, printed manual and earphone.

The price is $69.95 plus shipping–very reasonable, in my opinion. The best part is Universal Radio offers a reputable 60 day warranty with all of their used items.

I regularly check Universal’s used and demo list. Occasionally, great bargains pop up and I feel I can always buy from them with confidence as they check over each item before posting.

Click here to read our review of the PL-680.

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PL-680 and ATS-405 radio reviews now online

Tecsun PL-680: SSB display inaccuracy

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SWLing Post reader, Olli Turunen, writes:

I thought you would like to know this. I bought PL-680 few days ago and I noticed that mine has the display about 1 khz off. I contact Anna on Anon-Co and got a quick reply:

“I have received a response from the supplier regarding the 1 kHz deviation issue of the PL-680 radio. Unfortunately they consider this to be within their tolerance standards for SW reception. Overall, their standard is set to be +/- 0.5 kHz, which translates to 1 kHz on the LCD display. They understand the effect it may especially have for SSB listening, which is why fine tuning has been added as a feature.

For MW/AM the situation is a bit different. According to the supplier this is an issue that both the PL-680 and PL-660 radios have and cannot be avoided. As they indicate, unfortunately only the PL-880 has a special function for MW frequency calibration.”

I just checked my PL-680 and did a zero-beat in SSB against WWV on 10 MHz. If the BFO adjustment is correct when in the middle position, I can confirm that mine is almost 1 kHz too high as well.

For AM listening, a 1 kHz deviation isn’t noticeable. If you’re using ECSS, though, you’ll certainly have to fine tune the BFO accordingly. If locating a CW or SSB signal (in the ham bands, for example), you’ll also need to adjust the BFO fine tune control in advance.

Most importantly–and fortunately–when you turn on the PL-680’s synchronous detection, the receiver is exactly on frequency (at least on my early model PL-680).

Many thanks, Olli, for sharing this information! I’ll note this negative in the PL-680 review.

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