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Dave says not all Jameco power supplies are linear and regulated

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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Wojtek Gwiazda retires from RCI

Sean’s A15 Season International Broadcasting Statistics

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Many thanks to Sean Gilbert, International Editor at the World Radio TV Handbook, who is kindly sharing some international broadcasting statistics with us again. These statistics were originally posted on the WRTH Facebook group:

Seasonal Language Output Comparison

[F]or the top 19 languages used in international (and Domestic SW) broadcasting. There are 10 seasons worth of data to compare. In those 10 seasons, we have seen an overall drop of 33%, the biggest casualties being Farsi, German, Portuguese, Spanish, Russian, English & Indonesian. Tibetan is usually fairly stable with it’s output being pretty constant over the past 9 seasons – this season, however sees a huge increase in output (+69%), mainly due to the USA hiking output of the language this season. In sheer numbers of data lines (which is how this table has always been generated), English is the biggest casualty, dropping 104 transmission periods per week.

Click to enlarge.

A transmission period is based on the following data structure:
Shown below are 2 “transmission periods” for WWCR and 1 for WWRB. 2 in English and 1 in Spanish. These transmission periods cover a weeks worth of output on that frequency at that time for that broadcaster.

WWCR 1630-2100 English wcr 100 NAm,Eu,NAf daily 15825
WWCR 2100-2200 Spanish wcr 100 NAm,Eu,NAf daily 15825
WWRB 0100-0400 English wrb 100 NAm daily 3195

So a transmission period could, in reality, be from 5 minutes on a single day to 24 hours, daily, depending on the broadcaster. There are nearly 5000 of these entries in our database for this season (When I started at WRTH back in 2000, there were over 10000 entries). Of these 5000 entries, over 3600 are taken up by just 19 languages. The other 1400 entries share somewhere in the region of 200 languages/dialects and combinations! Although this doesn’t show how many hours a particular language has decreased by, it does show the ongoing trend in International broadcasting by radio.

A15 International Broadcasting Season Facts

There are 191 schedules listed in the International Radio and COTB (Clandestine & Other Targeted Broadcasts) section of the WRTH A15 schedules file.

Who uses the most frequencies? CRI, with a whopping 279 frequencies in use. The next largest station, by frequency use is (probably quite surprising to many of you) Voice of the Iranian Republic of Iran (VOIRI) with 140 (that is half the amount of CRI!). Next is VOA with 126; then RFA at 112; BBC at 110 then Sound of Hope Radio International with 84 and All India Radio at 67.

Below is a list of the ‘Top 20’ broadcasters in terms of frequency usage. If you were to do a study of actual transmitted time, the list would look rather different. I will shortly post a table showing the top languages, by use, and what has changed over the past 10 broadcasting seasons.

CHINA RADIO INTERNATIONAL (CRI): 279 frequencies
VOICE OF THE ISLAMIC REPUBLIC OF IRAN (VOIRI): 140 frequencies
BBG – VOICE OF AMERICA (VOA): 126 frequencies
BBG – RADIO FREE ASIA (RFA): 112 frequencies
BBC WORLD SERVICE: 110 frequencies
SOUND OF HOPE RADIO INTERNATIONAL: 84 frequencies
ALL INDIA RADIO (AIR): 67 frequencies
RADIO ROMANIA INTERNATIONAL (RRI): 56 frequencies
AWR ASIA/PACIFIC: 52 frequencies
RADIO JAPAN (NHK WORLD): 49 frequencies
VOICE OF TURKEY (VOT): 43 frequencies
RADIO TAIWAN INTERNATIONAL (RTI): 41 frequencies
BBG – RADIO FREE EUROPE/RADIO LIBERTY (RFE/RL): 33 frequencies
KBS WORLD RADIO: 32 frequencies
SAUDI INTERNATIONAL RADIO: 32 frequencies
AWR AFRICA/EUROPE: 30 frequencies
VATICAN RADIO: 29 frequencies
RADIO CAIRO 29: frequencies
VOICE OF KOREA (VOK): 27 frequencies
FEBC PHILIPPINES: 26 frequencies

63 broadcasters, or so, use just a single frequency.

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Improving audio fidelity with JBL C2PS monitor speakers

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Last year at the W4DXCC conference in Sevierville, Tennessee, I spent some quality time with Bob Heil (K9EID). Bob is the mastermind behind Heil Sound as well as the host of HamNation, a show devoted to all aspects of amateur radio––yet this job description only scratches the surface of Bob’s fascinating career.

Bob Heil (K9EID, left) and yours truly (right) at the 2014 W4DXX conference in Sevierville, TN

One thing is for sure, however: there are few people in the radio industry who truly understand audio as profoundly as Bob Heil, so when he announced that he would host a forum at the W4DXCC to assist amateur radio operators in improving their received (and transmitted) audio, we were all ears, and signed right up.

Early in the forum, Bob described a set of self-powered and relatively affordable JBL monitor speakers that he highly recommended for amateur radio use. Everyone in the room noted the model number of the speakers, myself included. So imagine my dismay after the convention when I simply couldn’t find my notes…

Thankfully, my buddy Gary Wise (W8EEY) recently jogged my memory. Gary purchased a set of JBL monitors and matching wall-mount brackets from Amazon, and has them hooked up to his Flex Radio FLEX-6700 SDR. Gary tells me he’s very pleased with the set-up. Here are the links:

Bob also suggests adding a small mixer to system, something like this Behringer Xenyx 802 or the XENYX502 (both of which are on my current wishlist).

Bob invited me to speak on HamNation about shortwave radio. I may take him up on the offer…well, as soon as I overcome my videophobia, that is. At any rate, if you’ve not seen it, HamNation is certainly worth checking out. And in all things radio, Bob Heil’s is a name to know; click here to visit Heil Sound.

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