Monthly Archives: December 2015

Woot Deal: Lenovo Rugged ThinkPad 11E-G2 11.6″ $199

After several failed attempts to use a Dell 7″ Windows tablet with my SDRs and D-Star DVAP, I decided to purchase either a Surface Pro (like my pal Mark Fahey used at the SWLing Post DXpedition) or a small Windows notebook computer.

This morning, I noticed a good deal on Woot.com: a Lenovo Rugged ThinkPad 11E-G2 11.6″ for $199 US. Woot actually had an identical deal about two weeks ago and I passed on it–since then, I’ve read mostly positive reviews about this notebook.

I’m a fan of Intel processors, but I’m pretty sure this AMD quad core processor combined with the speed of an internal solid state drive should handle most of my SDR spectrum recording needs. The Thinkpad also has a USB 2 and USB 3 port for external storage.

This small notebook is also MIL-SPEC Tested and comes with a full one year Levono warranty.

So I bit the bullet about 15 minutes ago.

I have purchased several items through Woot (hard drives, tools, telephones, etc.) and have only had good experiences.

If you’re interested in this deal, you must act quickly. It will only last until Woot sells out of inventory or the end of the day today (whichever comes first).

Click here to view on Woot.com.

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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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An iPhone app and Paul’s secret for successful reception reports

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Many thanks to SWLing Post contributor, Paul Walker, who writes:

Wether you do AM, shortwave, longwave, FM or something else, I think this will prove useful.

I have a pretty high return rate when submitting reception reports and asking for QSL cards/letters. I’d say my return rate is probably better than 60 percent, sometimes even 70 or 80 percent. It just depends.

But what helps me so much? EVERY reception report I email or snail mail includes an audio recording. Sometimes it’s only 30 seconds if the signal is really rough, weak or hard to pick out anything useable. Sometimes I include anywhere between 5 minutes and 30 minutes with a detailed report.

Well, how do I record? I use my smartphone! I have an iPhone 6 Plus with 128 GB of storage. iPhones record some of the best audio I’ve ever heard from a smartphone. Androids do a pretty decent job–not as good, but not bad.

The best app I’ve found for this is Voice Recorder Pro 7.

Click here to view Voice Recorder Pro 7 on iTunes.

Voice Recorder Pro 7 Screenshots

You can select the recording format (mp4, mp3 or wav), you can select the sample rate, bit rate (32kbps all the way up to 320kbps), you can select mono or stereo as well.

But where this really comes in handy? You can email the audio file to yourself or someone with the click of a button, you can upload it to a google drive, dropbox, one drive or a box cloud account. You can even have it upload to an FTP server or to your Facebook page if you want!!

The one feature I like is being able to turn audio into a YouTube video and uploading it directly! I was recording videos by holding it up to the radio’s display and while the audio was good, it wasn’t great because it was a bit further away from the speaker so I could show the S meter and frequency on the display.

So what I ended up doing is to put the phone right near the radio’s speaker and start recording… this produces better audio then a straight up video. Then you click a button after the recording is over and it generates the video frames for you, putting a picture there; you fill in the particulars of your video and it uploads it to your YouTube account.

See what I’m talking about here, by viewing my YouTube account:
https://www.youtube.com/user/OnAirDJPaulWalker

You can easily tell which videos were made by me holding up the phone to the radio’s display and which are audio only with the video generated by Voice Recorder Pro 7.

Here’s an audio only track I recorded to give you an idea how it sounds.

https://soundcloud.com/paul-walker-11/radio-mediterranne-international

I don’t recall if they have this app for Android phones, but if they don’t, there’s something similar. It’s worth investigating.

A detailed written report is one thing when requesting a QSL, but audio is indisputable and absolute confirmation of what was heard.

Many thanks for the recommendation, Paul. I use an Android phone (the Moto X 2nd generation). I’m hoping a Post reader can suggest a recording app that is equally robust.

Like you, I typically send an audio recording when submitting a reception report. It’s certainly a valuable piece of information for broadcast engineers. Thanks again!

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Michael comments on the Squires Sanders SS-IBS

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Regarding the Squires Sanders SS-IBS Dan recently spotted on eBay, SWLing Post reader, Michael Black comments:

[The Squires Sanders SS-IBS is] a legendary receiver that either brought new ideas to receivers, or brought them to the amateur radio level.

There’s an article in QST in 1963 from Squires about this new stuff, I’ve never seen it so I don’t know if he’s talking in abstract terms, or revealing this receiver.

A big difference is that there’s no RF amplifier before the mixer, and the mixer is balanced. But he throws some of that out by going to double conversion, I assume for tuning reasons. The first IF is 500KHz wide, the first oscillator is crystal controlled and the second oscillator is variable, as seen in top end receivers of the day. The alternative would be a tuneable oscillator that was switched per band (instability from the switch, and the higher the band, the higher the frequency, hence stability) or mixing the tuneable oscillator with a crystal oscillator before feeding the first mixer, which can cause spurs without proper filtering).

The second IF is 1MHz, and having a filter so high was relatively new, though maybe some rigs had moved up to HF filters at the time.

It apparently is fussy about the antenna, or matching, because of the lack of RF amplifier.

Soon there’d be receivers that converted to 9MHz or so directly, saying goodbye to most image problems. Heathkit had a general coverage receiver later in the sixties that had an IF, with crystal filter, at 1680KHz, a relatively cheap receiver with much greater image rejection on the higher bands. The ham band only Heathkit HR-10 used the same IF and filter.

The Heathkit HR-10 (Source: Heathkit Virtual Museum)

Then a bit later, synthesizers arrived that made it much easier to build better receivers.

There was a wave of building using the 7360 balanced mixer used in this receiver, and frontend q-multipliers to deal with the lack of front end selectivity. But as semiconductors and ICs came along, it became much easier for mixers to be balanced or double balanced.

Thanks for this insight, Michael–sounds like the Squires Sanders SS-IBS was quite the innovation of its time. Thank you for sharing!

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History of Gerald Marcuse G2NM, founder of Empire Broadcasting

Dan spots a Squires Sanders SS-IBS on eBay

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SWLing Post contributor, Dan Robinson, notes the following eBay link via the Extreme Shortwave Listening Facebook group:

“One of the rarest receivers, first one seen in years….famously pictured in the shack of the late Richard E. Wood from the 1970s… the Squires Sanders SS-IBS.”

Click here to view the Squires Sanders SS-1BS on eBay.

What a beautiful radio! I don’t think I’ve ever seen one int he wild. I’m pretty sure it’ll soar in price once the bidding truly starts.

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Best solution to restore a vintage plastic radio chassis?

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Friday, I brought home an untested, slightly grimy, Sony ICF-5500W. I purchased it through Goodwill for $20.

I crossed my fingers as I put three C cells in the radio and turned it on. Fortunately, I was rewarded with brilliant audio. I tuned the ‘5500W on AM/mediumwave and heard CFZM, 500 miles to my north, and Radio Reloj, 860 miles to my south. A quick scan on the FM dial revealed that I could also hear all of my local benchmarks. Whew!

Other than the dial needing a little calibration, and DeOxit on a few pots, it’s in excellent mechanical shape.

I started cleaning the radio last night using Q-tip cotton swabs and a vinegar/water solution.

I’d like to restore the hard plastic chassis’ original shine, though.

I was tempted to reach for some Armor All, but stopped myself short. I know it would give the ICF-5500W a nice shine, but would it cause any long-term damage to the black plastic or clear dial cover?

I know there are vintage radio restorers among the SWLing Post readership. Can someone offer advice on what’s the best product to use (or not use!) on my ICF-5500W?

If you have experience, please comment!

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