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Hamvention find: the Arvin 68R58 AM transistor radio

Though I believe I spent more money at the Dayton Hamvention this year than I have in all previous years, I only purchased one radio: the Arvin 68R58 eight-transistor.

I spent a whopping $5 on the little Arvin in the Hamvention fleamarket. To be fair, the seller sold it for this modest price because he was not sure if the radio worked. But when I unsnapped the back leather cover, peered inside, and found the works remarkably clean, I suspected it might…

No original power supply was included, of course, and I was a bit concerned when I saw the somewhat out-of-character plastic battery holder. In the filtered fleamarket light, it appeared to me as if it required proprietary batteries–the holder appeared too small for C cells, and too large for AAs. There was no indication of the type of batteries it used, but since the spec read “6 volts,” I knew I could build a small AA battery holder, if need be.

So, at $5 (I bargained him down from $10, based on the doubt of operation) it was a very low risk purchase, and a potentially a fun project.

Back at home, I popped open the battery holder and looked inside…And I discovered the Arvin did, indeed, take four C cells. Simple enough! After inserting fresh batteries, I turned on the radio via the tone pot, and instantly heard beautiful, rich audio.

What I thought would be a project radio ended up being fully functional, and was, moreover, in tip-top shape.

So far, I’ve been very impressed with the Arvin’s AM sensitivity and audio fidelity. No doubt the generous ferrite rod antenna is doing the trick on medium wave.

Last night, as I tuned through the AM broadcast band, I was able to null out unwanted stations and noise amazingly well. There is something to be said of transistor radios from this era–let’s just say, they’re classics.

The Arvin has a simple set of controls: tone, tuning, and volume. There are no filter selections, of course, but I can tell that it’s quite wide; perhaps 8 or 9 kHz.

All in all, I’m very pleased with my little purchase, and the Arvin has become my new (vintage) bedside radio. Last night, I tuned in one of my favorite AM stations on 740 kHz, CFZM in Toronto, Canada. CFZM (a.k.a. “Zoomer Radio”) is not only a benchmark, but a right of passage for any worthy AM radio in my household. The Arvin passed the Zoomer test with colors flying.

And, yes, it even soothed me to sleep.

Now I only need to properly clean and restore the Arvin’s leather chassis and perhaps build a 6V-regulated linear power supply.

Next time you pass by a 1960s/70s vintage transistor, grab it! I’m certainly happy I did.

Now, I think I’ll turn on the Arvin, sip some dark beans, and put up my feet in the Pawley’s Island hammock…Cheers! Summer’s on the way.

Want one of your own? A quick search reveals that the Arvin 68R58 can be found on eBay for quite reasonable prices. Click here to search eBay for an Arvin.

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Honoring Memorial Day: The White Cliffs of Dover

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Dame Vera Lynn

Today is Memorial Day, and I’m feeling humbly grateful to all of those who paid the ultimate sacrifice for their country. Since I’ve been reading a lot of WWII history lately, I’ve also been playing a lot of WWII-era music here in my sanctuary to all things radio.

Few songs sum up the yearning sentiment of World War II better than Vera Lynn’s 1942 rendition of “The White Cliffs of Dover.” It’s an iconic song, one that helped British soldiers see beyond the war while mourning its painful toll. It was written in 1941 when England was taking heavy casualties, just before American allies joined the effort.

This morning, seeking something with a little authenticity, I played “The White Cliffs of Dover” though my SStran AM transmitter, and listened to it through “Scottie,” my WWII-era Scott Marine radio (above). I made this recording by placing my Zoom H2N recorder directly in front of the Scott’s built-in monitor speaker.

So here you go: a little radio tribute to all of those who fell–on both sides–of that infamous second world war.

And thanks to all who serve and have served in the name of “peace ever after.”

Click here to download the recording as an MP3, or simply listen below:

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Dave says not all Jameco power supplies are linear and regulated

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Note that not all power supplies are listed as “regulated linear”

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who replies to a post published yesterday regarding some of Jameco linear power supplies. Dave writes:

“A bit of a caveat on Jameco’s these so called Linear power supplies. This is based from my own experiences so is not fiction.

Bottom of this page : http://www.jameco.com/Jameco/catalogs/c151/P92.pdf

Over the years some of (but not all) these Jameco linear regulated power supplies are no longer clean for radio use.

Without changing the model number or description of the product, they have made changes with some (or much of ??) this “Linear Regulated” adapter line. Indeed they are still using a good old power transformer, but when it comes to the regulator part of the adapter, they have gone to switching type regulator device. So it produces a nice strong whine on a radio receiver just as a full fledged switching supply.

I had purchased a number of these so called linear supplies (sorry I no longer have the exact model number noted that I ordered) and experienced awful interference with any radio receiver. So I cracked open one of these to see what was up here and sure enough it was using a MC34063A inverting switching regulator .

Called Jameco and they flat out denied that they were using any switching devices in this Regulated LINEAR Jameco ReliaPro adapter. So I then sent a nasty gram email to the CEO of Jameco. I received an email back (was from the CEO too) and after some research they FINALLY did admit a change was made in some of the product line to use of a switching regulator . But he strongly made the point they would continue to still market these adapters as totally linear (yeah right ….nice guys).

I must add here that it does (or did not) NOT affect the entire line of these linear regulated adapters. About a year ago I ordered more (already had a few before) of the 12 volt 1 AMP model 170245 , and these are (or were anyway) totally clean and are excellent.

Also note that Jameco purchases up surplus “linear regulated” adapters from time to time. This 6 volt 500 ma one here is an example and is (or was anyway) nice clean one and uses no switching regulators. Our 2 tested samples of this adapter from about 5 years ago used a nice 7806 analog regulator. Perfect for use with many SW portables, (including the Sony ICF-SW7600GR with a plug change). But a warning again from experience , they are all subject to changes without any warning (and this one may have changed too for all we know ??)

They appear to stick the ReliaPro name as the manufacture on all adapters (if it was made by Jameco or not)

So Caveat Emptor.”

Duly noted, Dave! I’ve also noted that not all of the power supplies on their linear power supply page are listed as being a linear supply (see screen grab at top of page).

I may contact Jameco about this too and see if they can adjust their search results to properly reflect a selection of regulated linear supplies.

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How to replace a noisy wall power supply

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Regarding noisy switching power supplies, SWLing Post reader, Dan Lewis, comments:

“Google the following: “Jameco linear wall transformer”, and you’ll find a suitable non-switching replacement.

Jameco still has a number of linear transformers in their catalog at reasonable prices. I haven’t bought anything from them in many years but when I dealt with them frequently a number of years back they were always reputable.”

Many thanks for your suggestion, Dan! Jameco is a reliable company and I’ve also been a long-time customer. If you know how to pick the proper power supply for your radio (or any other electronic device) click here to view a list of regulated linear supplies on Jameco’s website. [Also note this follow-up post.]Otherwise, keep reading…

How to find a replacement AC adapter/power supply

When you purchase a replacement power supply, you must make sure that several properties match that of the device it will power, else you could cause damage.

There are four properties you need to match: voltage, rated current, polarity and tip size.

Voltage

Most consumer electronics are powered by and rated for 4.5, 5, 9, 12, or 13.8 volts DC. Of course, there are exceptions. It is important that you match the required voltage exactly. Most radios and electronic devices display their required voltage and voltage tolerance on the unit itself, on the supplied switching power supply, and/or in the owner’s manual.

Rated Current

Like voltage, rated current is usually displayed somewhere on the device, existing power supply or in the owner’s manual. Current is usually indicated in amps (A) or milliamps (mA). Unlike voltage, rated current on your power supply does not have to match the device exactly. You simply need to make sure the power supply meets or exceeds your radio’s required current.

For example, if your radio requires 800 mA (or .8 A) and you find a power supply rated for 500 mA, you should not use it. If you find a power supply rated for 2 amps (or 2000 mA), it exceeds the 800 mA rating, so you’re good to go!

Unlike voltage, your electronic device or radio will only draw the amount of current it needs from the power supply.

Polarity

Click here to read more about tip polarity. (Source: WikiPedia)

You’ll need to determine if your radio requires a plug with a positive or negative tip (a.k.a. center conductor).

Fortunately, manufacturers have long used standard symbols to make polarity obvious (see image).

You’ll typically find a polarity symbol printed on the back of your radio, near the plug-in point, in the owner’s manual or on the back of the existing wall adapter.

Note: Be very careful matching polarity! Some radios and electronic devices are not properly protected against reverse polarity; damaged can occur immediately after supplying voltage with incorrect polarity.

Tip/plug size

You need to make sure that the inner diameter and outer diameter of a replacement wall adapter will match that of your existing adapter.

This can be the most difficult property to match.

Occasionally, radio manufacturers will actually specify the tip size in their owner’s manual, spec sheets, or on the product page of their website. I’ve even had luck calling manufacturers and asking a technician for the plug size.

Specification sheets will typically indicate plug dimensions with an illustration.

Otherwise, you can always measure the existing power supply tip (both inner and outer dimensions) using calipers.

Once you have those dimensions, finding the appropriate replacement power supply is quite easy. Indeed, companies like Jameco provide specification sheets (click here for an example) that indicate dimensions for each power supply they sell.

Once you’ve matched the voltage, rated current, polarity and tip size, you can purchase a regulated linear power supply with confidence!

Keep in mind: there are most likely other devices in your home with noisy switching power supplies that could be causing radio interference. Check out my noise trouble shooting section of this article to help identify local sources of radio noise.

Update: check out this follow-up post regarding Jameco power supplies–not all are truly linear regulated.

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National Radio Quiet Zone featured in BBC Radio 4 series

Jeffrey re-caps his Hallicrafters SX-110

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The restored SX-110 sitting on the bookshelf in the shack.

Many thanks to SWLing Post reader, Jeffrey Fritz, writes:

During the summer of 2012 you were nice enough to run an article in your blog about my reviving a 1961 Hallicrafters SX-110 General Coverage receiver. The radio has continued to perform reasonably well during the last few years. However, recently I acquired several pieces of professional test equipment. That encouraged me to delve even deeper into the restoration of my old receiver from my novice ham radio days.

Over the past week, I completely recapped the SX-110 (except, of course, for the mica and ceramic caps as they still good, and the electrolytic caps as they were replaced in 2012.)

The SX-110 isn’t a complex receiver, but there are quite a few caps, so I worked methodically and carefully. I started working from the audio amp stage and continued working back through the IF stages and the BFO to the RF stage. I recapped each stage replacing the old caps with new Orange Drop caps. Each stage was tested before I moved on to the next stage. Here’s a photo of the recapped chassis:

Here are the capacitors that were removed from the receiver. Most are the old Bumble Bee caps–called that because of the color stripes that mark their value:

Virtually every Bumble Bee cap tested leaky and out of tolerance.

Next, I tested every tube replacing the weak or bad ones with NOS (New Old Stock) tubes. Every pot and switch was cleaned with DeOxit and moving parts were lubricated where appropriate. Finally, I did a complete re-alignment following the instructions in the Service Manual.

As with all vintage tube gear, restorations require patience, care and a decent knowledge of electronics. It’s easy to make a fair radio–even a good radio–into a disaster if you are not careful. Also there is enough voltage and current inside of the chassis of a tube radio to toss you across the room. So care is always the order of the day as is a VARIAC to bring the radio up to AC line voltage slowly.

The receiver now sounds as good as ever–perhaps even better than ever. It has marvelous AM audio and can pick up ham and broadcast stations on all bands with nothing more than a wire in my basement. It even does a decent job on SSB–something that I don’t recall it ever bring adept at in the past.

That say that you can’t keep a good man down. Similarly an old radio, with some new parts and some TLC, can run virtually forever.

I agree with you: you can’t keep a good radio down! Repair work is certainly the commitment we make when we fall in love with these old rigs. It’s a good thing that almost all of the parts are still available and relatively affordable.

Thanks again, Jeffrey!

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