Tag Archives: Sony SRF-39FP

Ultralight DX: A batch of inexpensive Sony SRF-39FPs found on eBay

Many thanks to SWLing Post contributor, Vance Thompson, who writes:

Thought you might be interested to see that several SRF-39FP radios have been up on eBay recently at a fairly reasonable price.

I picked one up when they first were posted, but the price has gone down the last couple of days and even has a “make offer” option with free shipping.

Click here to view on eBay.

The description indicates that they are pre-owned by inmates at a Tennessee federal prison. As of this writing, there are 8 left.

The one I got was in pretty good shape cosmetically, all things considered, and works perfectly. Given that a brand new FP version of the SRF-39 is not likely to be seen again at $20, a used one such as this with a bit of history is not a bad deal for those of us that missed out when snagging one new was an option.

Although it makes me wonder what they are being swapped out for and if we might see an increase of these pre-owned ones coming up on eBay now.

Thanks for sharing, Vance! Twenty dollars (or possibly less through a Best Offer) is a fantastic deal, in my opinion, for the elusive SRF-39FP. Click here to read out previous posts about the SRF-39FP. Indeed, I’m mighty tempted to drop $20 on a spare unit myself. (Thanks for enabling me, Vance!)

It appears the seller has a stellar reputation on eBay too.

Click here to view this Sony SRF-39FP on eBay.

Click here to search eBay for other SRF-39FP listings.

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Battery Endurance Contest Results: Sangean DT-160CL vs Sony SRF-39FP

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On August 4, 2016, the same day I received my new Sangean DT-160CL, I popped a fresh set of CVS Max Alkaline batteries into the DT-160CL as well as into my trusted Sony SRF-39FP. The mission? To see which radio could perform longest on a set of batteries.

I set my stopwatch as I turned on both radios, tuned to the same frequency, set the volume to the same levels…and waited.

And waited. And waited. And as I waited, I posted updates.

But at last, the waiting is at an end: here are the contest’s final results.

Sangean DT-160CL: Impressive Performance

On August 9, I reported that the Sangean DT-160CL finally threw in the towel, logging an impressive 116 hours 30 minutes of operating time–!

Without a doubt, this is one of the longest run times I’ve ever experienced from an AM/FM radio with digital display.

Interestingly, the day after the DT-160CL shut down, I turned it back on, and it operated for an additional 45 minutes or so, obviously absorbing a little more voltage from rested cells. During that 45 minutes period of time, the audio and overall performance was respectable. No doubt the DT-160 shuts down before audio is terribly compromised.

Sony SRF-39FP: The Endurance King!

Amazingly, the Sony SRF-39FP kept running well beyond 116 hours. Well beyond…

By Wednesday morning–one full week from the time I began the endurance contest–the Sony SRF-39FP finally began showing signs of low-voltage: the audio had a small amount of splatter and sensitivity began to be compromised.

Unlike the Sangean DT-160CL, which clearly has a cut-off voltage, the SRF-39FP kept milking the battery for its last vestiges of power.

I decided that I would call a “time of death” for this AA battery when the Sony struggled to receive local AM stations, as well as transmission from my in-house SStran AM transmitter.

This happened approximately 163 hours and 54 minutes into its marathon run.

This stopwatch app tracked the full endurance test. I pressed “stop” when the Sony SRF-39FP finally gave up.

Wow, wow, wow. I simply had no idea any portable could operate almost one full week on one AA cell–!

In truth, I’m sort of relieved the ’39FP finally gave up the ghost. I was beginning to think the thing was powered by some supernatural force…

When I started this test, I thought the Sony SRF-39FP was rated for about 40-80 hours of run time on a single battery. I couldn’t remember where I got that number until I recently re-read this article from The New Yorker, which highlighted the 39FP’s role in correctional facilities:

“The SRF-39FP is the gold standard among prison radios in part because it runs on a single AA battery, and offers forty hours of listening time…”

Wait, just forty hours? Perhaps from the cheapest AA battery made…

With an advanced chemistry cell like the Duracell Quantum or Energizer Advanced Lithium series, you’ll clearly get three to four times that performance.

DX mode

And here’s the thing: I’m convinced I could’ve gotten much more time out of the SRF-39FP.

Like similar Sony portables, the SRF-39FP has a “DX/Local” switch. When set to DX, the receiver is made to deliver maximum performance.

If you’re listening to a local station, however, “Local” mode is a better choice. You’ll still be able to receive your target station, yet draw much less from the battery.

I left the Sony SRF-39FP in “DX” mode for the entire battery endurance test. Had it been in “Local” mode, I believe I’d be reporting an even longer run time. How much longer, I don’t know, but you can bet that my curiosity will soon get the best of me…I plan to do a separate endurance test to find out.

Clear choices for battery longevity

Sangean-DT160CL and Sony SRF-39FP No doubt, our little test has proven that radios marketed to the prison system do offer excellent battery performance.

Now I’m very curious whether the standard Sangean DT-160 will offer the same battery performance as its clear-cased counterpart, the DT-160CL. The only difference in the two appears to be that one offers a clock, while the other doesn’t. I wonder if that would have any significant difference on battery life.

Additionally, the Sony SRF-39FP has shown us that analog receivers can be much more efficient than their digital counterparts. We’ve known this a long time at Ears To Our World, and which is why almost all of the radios we supply to schools in remote, rural locations are analog.

Sadly, analog radios are getting much more difficult to find these days as DSP-based receivers have become more affordable to produce.

The Sangean DT-160 is available at Amazon.com and Universal Radio. The Sangean DT-160CL (the version tested) is available through Amazon.

Click here to search eBay for the Sony SRF-39FP.

Readers: Know of any other battery-miser radios? Please comment!

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Update 4: Sangean DT-160CL v Sony SRF-39FP

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If you’ve been following the Sangean DT-160CL versus Sony SRF-39FP battery endurance test, I have some news to report: one of our competitors has finally thrown in the towel…!

Yesterday, while I was on the road for about 1.5 hours, the Sangean DT-160CL at last gave up the contest.

Since I was traveling at the time, I can’t say with absolute certainty what o’clock the DT-160 cried uncle––but roughly, we’re looking at 116 hours, 30 minutes of run time, give or take 30 minutes.

Sangean claims the DT-160 series will operate for 100 hours with two AA batteries. That claim is obviously pretty conservative.

Though I used CVS Max Alkaline batteries (a generic version of Duracell’s Quantum batteries)–an improvement on the standard alkaline battery–I set the volume higher than I believe Sangean or Sony would have set it for testing purposes. This should have drained the batteries faster. The radios were also tuned to a variety of stations: weak AM, strong AM, weak FM and strong FM.

In short: I’m very impressed with the DT-160.

A 116 hour play time from two AA cells on a digitally-tuned receiver is, well, pretty incredible.

Now that the endurance test is over for the DT-160CL, I’ll replace the batteries with a fresh set of CVS Max Alkaline cells and start testing the AM/FM receiver performance.

…And how about the Sony SRF-39FP?

My iPhone’s stopwatch has been tracking progress since last Wednesday.

Even more amazingly, the Sony SRF-39FP is still going strong––!

I actually fell asleep last night listening to the SRF-39FP and woke up this morning with music still in my ears. What a champ!

So, how long has the Sony SRF-39FP now been operating on one AA battery?

At time of posting, this little Sony’s clocked one hundred thirty nine hours.

Though I’ve always known that the SRF-39FP was a true battery miser–one of the reasons it’s been a choice radio in the prison system–I had no idea it could operate this long on one battery.

Of course, I’ll continue tracking the Sony SRF-39FP.

How much longer will the SRF-39FP last? Stay tuned to find out!

Follow this review thread by bookmarking the following tag: Sangean DT-160CL v Sony SRF-39FP.

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Update 3: Sangean DT-160CL v Sony SRF-39FP

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My iPhone’s stopwatch has been tracking the endurance test.

It’s been one hundred nine hours since I started the Sangean DT-160CL versus Sony SRF-39FP battery endurance test and both radio are still hanging in there!

Not knowing which radio will check out first, I’ve been taking them with me everywhere and have been careful to keep their settings identical the whole time.

Last night, I even prepared my Zoom H2N digital recorder to monitor both radios simultaneously. Having passed 100 hours of operating on the same set of batteries, I was certain one would call it quits last night.

Not so.

There was one noticeable change this morning: the Sangean DT-160CL’s battery indicator now shows a depleted cell.

It’s still operating, though–no noticeable difference in volume and reception.

The end must certainly be near! Indeed, it’s hard to believe I started this endurance test last Wednesday!

I’m very interested to see which pocket radio will go first.

Field time

Yesterday, I spent the better part of the afternoon at Mt. Mitchell State Park. Of course, I brought the DT-160CL and SRF-39FP along.

Mt. Mitchell is the highest point east of the Mississippi river. It’s a great place to play radio.

At one point, I tuned both radios to WAIZ 630 kHz: a 1,000 watt AM station about 95 miles east of the park. It’s one of my benchmark daytime stations from Mt. Mitchell.

Though most DT-160 reviewers have given the receiver low marks for AM performance, I found that the DT-160CL did a better job locking onto WAIZ than the venerable SRF-39FP.

Perhaps this is due to the fact that both radios, at that point, were operating on low voltage? Or perhaps the CL version of the DT-160 series has better AGC characteristics and sensitivity?

I doubt the latter assumption, but once the endurance test is complete, I’ll put the 160CL through the paces.

Follow this review thread by bookmarking the following tag: Sangean DT-160CL v Sony SRF-39FP.

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Update 2: Sangean DT-160CL v Sony SRF-39FP

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It’s been eighty seven (!!!) hours since I started the Sangean DT-160CL versus Sony SRF-39FP endurance test and both radio are still going strong.

My iPhone stopwatch has been tracking the test.

I’ve tuned both radios to my SSTran AMT3000 AM transmitter which is currently re-broadcasting the UK 1940s Radio Station on 1570 kHz.

The Sangean DT-160CL still shows two of three segments on the battery indicator (see above).

The Sony SRF-39FP seems to have no indication of quitting anytime soon–it’s still sensitive and audio sounds great.

I believe the Sony SRF-39FP is rated for 80 hours of playtime, and I’m sure if I had turned it on and off numerous times during the test, it might have had an impact on battery performance. It’s still going strong, though.

I am using advanced alkaline (CVS Brand) batteries in both radios. These should give each radio better battery life than standard alkaline or rechargeables.

Regardless which radio wins this test: both have already proved themselves “Holy Grail” battery misers!

I’ll be monitoring the radios very closely today as we pass the 90 and 100 hour mark!

UPDATE: Shortly after making this post–at almost exactly 88 hours and 30 minutes into the test–the Sangean DT160CL’s battery indicator lost a battery indicator segment. It’s now only showing one of three battery segments. Could the end be near for our DT-160CL? Stay tuned!

Follow this review thread by bookmarking the following tag: Sangean DT-160CL v Sony SRF-39FP.

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Update: Sangean DT-160CL v Sony SRF-39FP

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It’s been thirty seven hours since I started the Sangean DT-160CL versus Sony SRF-39FP endurance test and both radio are still going strong.

So far, the DT-160CL’s battery indicator still shows full voltage. The SRF-39FP has no battery indicator, but through experience I know it’s nowhere close to quitting.

I’ve spent some time tuning both radios and comparing them on mediumwave/AM and FM.

The DT-160CL does an amazing job on the FM band and has a definite edge on the SRF-39FP.

On AM, however, the SRF-39FP seems to wipe the floor with the DT-160CL.

In truth, though, it’s tough to evaluate performance and audio while the endurance test is ongoing, so I should reserve judgement. During the battery endurance test, I’m using the supplied earbuds from both radios. The Sangean’s earbuds a fairly large and uncomfortable in the ear–they make the audio sound hollow and too focused on mid-range tones. In truth it’s pretty much the same thing for the 39FP’s buds.

I can’t wait to use some of my proper in-ear buds on the DT-160CL and evaluate its audio characteristics on AM and FM.

Follow this review thread by bookmarking the following tag: Sangean DT-160CL v Sony SRF-39FP

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Unboxing the Sangean DT-160CL and setting up an endurance test

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Yesterday, I received my Sangean DT-160CL–the correctional version of the DT-160–from Amazon.

Even though the Amazon product page showed 5 units in stock on July 29, and though I get free two day shipping via Amazon Prime, my DT-160CL took four business days to arrive. Out of curiosity more than anything else, I asked Amazon why the delivery would take four business days instead of two my Prime membership promises.

Amazon replied that stock levels weren’t correctly displayed on the product page at time of ordering since the DT-160CL was selling so quickly.

Amazon apologized for the confusion and–though I wasn’t seeking one at all–they issued a $10 credit! Wow–thanks, Amazon!

The DT-160CL is supplied with a set of clear earbuds, an owner’s manual and a warranty card.

The Sangean DT-160CL is very close in size to the venerable Sony SRF-39FP–the SRF-39FP has slightly more depth and a little less height.

The DT-160CL’s clear case, while sturdy, feels marginally more supple than that of the Sony SRF-39FP. Though I haven’t been able to confirm, the DT-160CL chassis feels like a polypropylene product while the SRD-39FP feels like polycarbonate. From the photos above, one can see that the DT-160CL’s case is a touch more opaque/cloudy than that of the SRF-39FP.

Endurance test

Other than overall receiver performance, I’m very interested in battery performance since Sangean touts a 100 hour run time on two AA batteries (for the DT-160 series).

Having used the Sony SRF-39FP for a few years, I can attest to an incredibly long battery life as well. No doubt, those purchasing the DT-160CL for use in a correctional facility place a lot of value on battery performance.

I stopped by our local CVS pharmacy to purchase fresh alkaline batteries for both radios. CVS had a sale on their own (generic) version of the Duracell Quantum alkaline batteries. I purchased a set and popped them in both radios.

The DT-160CL has a hinged battery cover and holds two AA cells.

The SRF-39FP only needs one AA battery.

After plugging in the supplied clear ear buds, I turned both radios on and adjusted the volume to a comfortable, moderate listening level.

I matched the audio levels for both units and tuned to my favorite classic rock FM station: WXRC 95.7 MHz.

WXRC is a fantastic benchmark FM station as it’s about 130 miles away (as the crow flies), but has an exceptional propagation footprint. My best FM receivers, when ideally-placed in my home, and telescoping antenna fully-extended, can receive WXRC in stereo lock with no interference.

I’m happy to report that both the DT-160CL and the SRF-39FP can receive WXRC quite easily when I’m holding the unit in my hand and standing in a part of my house where the signal is strongest.

In truth, I didn’t have time to evaluate receiver performance last night–I was more eager to begin the endurance test which, by the way, officially started yesterday (August 3, 2016) at 22:30 UTC.

I can’t wait to discover which radio will win!

Follow this review thread by bookmarking the following tag: Sangean DT-160CL v Sony SRF-39FP

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