My VERY NOISY Sony CRT TV has gone to the great electronics recycling bin in the sky thank goodness. But I still have a MFJ-1026 here and need to use it when the neighborhood gets noisy. Intermittent power line noise is the main issue these days for me.
[Note that] my Monitoring Times review from April 2007 on the MFJ-1026 (and 1025 model without the preamp, but is best to have it) is still available here :
I still power it with a analog REGULATED Jameco 170245 12 volt (1 amp) ac adapter.
Last batch I purchased a few years ago were still 100% clean and analog regulation. As I have covered in the past, SOME of Jameco excellent REGULATED AC adapters have gone to using switching regulator devices inside (and these no longer clean for any radio use).
DX Engineering is about to come out with a improved version of the premium priced NCC-1, called the NCC-2. Mid late November Delivery ?? Never had our hands on one the pricey NCC-1 critters as the MFJ gets the job done for us (let alone affording it).
Autonomous power supply of our active antennas via USB and power bank
It is getting to be more and more difficult to procure reasonably priced analogue external plug-in power supplies because just like old light bulbs they are no longer allowed to be produced due to power consumption restrictions. We are spending a lot of time to find and buy remaining stock so that we can offer our customers noise-free external power supplies. But for years, there has been an alternative.
Our MegaLoop ML200, ML052, the MegActiv MA305 as well as the GigActiv GA3005 can be operated internally with as little as 5V and so can be powered by the supplied CPI1000DP / CPI3000DP bias tee via a USB cable. In light of the annoying switching power supplies, PowerLAN and heightened mobility of listeners, this is a very practical alternative and offers much more flexibility for the customer. Unfortunately, this fact is not well known and that is why I would like to shed some light on this subject.[…]
I should note that there are a multitude of 5 VDC powerblocks on the market. I have two made by Eton Corp (see above) that even have hand-crank power generation. I recently used one to power my Raspberry Pi (Raspberry Pirate!) for several hours.
As Dennis states, using a DC source certainly cuts down on interference from noisy power supplies.
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.
“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.”
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.
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.
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.
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.
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.