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  #1 (permalink)  
Old 06-16-2018, 8:09 PM
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Default Experimenting

I have a Sunforce AC/DC Power Converter attached to a Jtron Dc 12v 10a Car Male Cigarette Lighter Plug with a Uniden 40-Channel CB Radio (PRO505XL) and a basic magnetic antenna all brand new hooked up in my home .The cb powers up and it has a humming sound like a fan running and if i turn the volume way up the humming gets softer but then it's to loud ? I turned off my fans and computer and still hear the humming .Any ideas ?
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Old 06-16-2018, 8:34 PM
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Tell us more about the "Sunforce AC/DC Power Converter".

Sounds like a noisy power supply, to me.
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Old 06-16-2018, 8:49 PM
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One more question,
Does the CB do this when you plug it into your vehicle?
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Old 06-16-2018, 9:47 PM
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Default Sunforce AC/DC Power Converter

it's on Amazon Sunforce AC/DC Power Converter


Technical Information-Device Supported-Antenna: Power Description-Input Voltage-110 V AC:Power Description-Frequency-60 Hz: Power Description-Output Voltage-12 V DC: Power Description-Fixed Output Voltage-12 V DC: Physical Characteristics
Weight (Approximate)-1 lb:
Technical Information-Device Supported-Antenna: Power Description-Input Voltage-110 V AC:Power Description-Frequency-60 Hz: Power Description-Output Voltage-12 V DC: Power Description-Fixed Output Voltage-12 V DC
Converts 110 Volt AC wall outlet into a 12 Volt DC plug
Ideal for use with coolers, spotlights, fans, cell phones and more
Small and compact
Input 100-120 VAC; Output 12v DC - 5.8A
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Old 06-16-2018, 9:51 PM
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That's a nasty little switching power supply that will cause lots of interference to radio equipment. You need a power supply better suited for use with radios.


Quote:
Originally Posted by Quadman65 View Post
it's on Amazon Sunforce AC/DC Power Converter


Technical Information-Device Supported-Antenna: Power Description-Input Voltage-110 V AC:Power Description-Frequency-60 Hz: Power Description-Output Voltage-12 V DC: Power Description-Fixed Output Voltage-12 V DC: Physical Characteristics
Weight (Approximate)-1 lb:
Technical Information-Device Supported-Antenna: Power Description-Input Voltage-110 V AC:Power Description-Frequency-60 Hz: Power Description-Output Voltage-12 V DC: Power Description-Fixed Output Voltage-12 V DC
Converts 110 Volt AC wall outlet into a 12 Volt DC plug
Ideal for use with coolers, spotlights, fans, cell phones and more
Small and compact
Input 100-120 VAC; Output 12v DC - 5.8A
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Old 06-16-2018, 10:40 PM
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non regulated power supply,, will be noisy and doubtful if it will give enough amperage,,,,
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Old 06-16-2018, 10:56 PM
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Default CB

Ok this is the cb I am trying to run it to is on amazon Uniden 40-Channel CB Radio (PRO505XL)
What power converter do you guys recommend ? I was trying to go cheap while experimenting I am wheelchair home bound and mostly want to listen because the scanners are expensive this was my backup lol .Thanks
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Old 06-17-2018, 12:02 AM
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mmckenna I do not know if it does or not .I am unable to hook it up in a vehicle. But if it helps I literately opened everything new today out of the box and hooked it up .
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Old 06-17-2018, 12:06 AM
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"antenna all brand new hooked up in my home"

Likely the culprit.
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Old 06-17-2018, 12:19 AM
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Default Antenna

The antenna is also new out of the package .
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Old 06-17-2018, 12:32 AM
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Where is it placed?
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Old 06-17-2018, 12:40 AM
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Quote:
Originally Posted by Quadman65 View Post
mmckenna I do not know if it does or not .I am unable to hook it up in a vehicle. But if it helps I literately opened everything new today out of the box and hooked it up .
New does not necessarily mean it's good.

However, I suspect it's working as designed, which is as a poorly filtered power supply designed for running non-critical devices.
The issue is likely that the DC output has a big enough AC component to create the noise on your CB. It's important to have clean DC power for communications use. A 12 volt battery would give you clean 12 volt power, which is why I suggested trying it in a vehicle to prove the theory that it's the power supply.

What you need is a quality 12 volt regulated power supply. There are many that will work and are designed for communications use. If all you need to run is a CB, then a 5 amp supply would be fine. If you ever decide to run more radios, you might want something bigger.

Your budget would dictate what I'd suggest. If you need to keep the costs down, then something like this should work:
https://www.amazon.com/Pyramid-Suppl...t+power+supply
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Old 06-17-2018, 9:50 AM
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I understand New does not necessarily mean it's good I was just telling everyone it's new equipment to help eliminate what it might be. So the converter with higher AMP output will make less noise ?
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Old 06-17-2018, 11:27 AM
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a regulated converter will make less noise,, higher amperage will just make sure the radio will have enough juice,,,, low amperage makes the radio do odd stuff,,, ya need a 5 amp or more power supply for the radio,,,, regulated means that the converter has transistors and filter capacitors in it to take out the ac hum and ripple
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Old 06-17-2018, 12:33 PM
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Default Pyramid Bench Power Supply |

So this should work correct guys ?

Pyramid Bench Power Supply | AC-to-DC Power Converter | 10 Amp Power Supply (PS12KX)


Hobbyist Bench Power Supply - 10.0 Amp (Constant), 12.0 Amp (Surge) - 12V DC Linear / Regulated Power Supply Design
Provides Constant Source of DC Voltage - Simple Electronic Plug-in Operation, Hassle-Free Screw Terminal Connectors
AC-to-DC Power Conversion Safe for Work Station & Tabletop Placement - Built-in Cooling Fan - Power ON / OFF Switch
Eliminates the Need of Battery or External Power Source - Built-in Electronic Overload, Short Circuit & Overload Protection
Rugged & Durable Cabinet Heatsink & Housing - Used for Component & Device Equipment Testing, Operation & Performance
Perfect For Home, Shop & Hobbyist.
Powers 12V Dc Devices Such As Cellular Phones, Cb Radios, Scanners, Etc.
Convenient Cigarette Lighter Plug Lets You Power Anything That Will Run Offf A 12V Car Cigarette Lighter.
Output: 13.8V Dc, Screw Terminal Connectors.
12 Amp Surge / 10 Amp Continuous.
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Old 06-17-2018, 1:16 PM
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It "should", but again, reading the reviews on Amazon shows some unhappy customers.

The specification and "linear" design, if properly filtered, so operate your CB just fine.
However, if your budget isn't an issue, you can get higher quality power supplies with better customer ratings.

I've been running an Astron SS-18 power supply pretty much continuously since 2003. It's currently powering a 45 watt VHF radio in my home.
I've got a few Duracomm power supplies at work that have performed well.

The extra current capability means you can add additional radios down the road if you want.
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Old 06-17-2018, 1:16 PM
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That Pyramid supply should work fine for what you are doing. Your current power supply is well regulated, but its a crude switching supply that puts out lots of RF interference and its intended for use with non radio type equipment as mentioned in its advertisement.

A 'linear" power supply like the Pyramid is old school, big transformer to step down the 120V AC to something less, filter caps and a regulator to keep the output voltage constant. There is no circuitry inside to generate RF noise like in a "switching" type power supply.

Some switching supplies work great with radios but they have adequate filtering built in to keep interference out of radio equipment, but this comes with more complexity and higher cost.


Quote:
Originally Posted by Quadman65 View Post
So this should work correct guys ?

Pyramid Bench Power Supply | AC-to-DC Power Converter | 10 Amp Power Supply (PS12KX)


Hobbyist Bench Power Supply - 10.0 Amp (Constant), 12.0 Amp (Surge) - 12V DC Linear / Regulated Power Supply Design
Provides Constant Source of DC Voltage - Simple Electronic Plug-in Operation, Hassle-Free Screw Terminal Connectors
AC-to-DC Power Conversion Safe for Work Station & Tabletop Placement - Built-in Cooling Fan - Power ON / OFF Switch
Eliminates the Need of Battery or External Power Source - Built-in Electronic Overload, Short Circuit & Overload Protection
Rugged & Durable Cabinet Heatsink & Housing - Used for Component & Device Equipment Testing, Operation & Performance
Perfect For Home, Shop & Hobbyist.
Powers 12V Dc Devices Such As Cellular Phones, Cb Radios, Scanners, Etc.
Convenient Cigarette Lighter Plug Lets You Power Anything That Will Run Offf A 12V Car Cigarette Lighter.
Output: 13.8V Dc, Screw Terminal Connectors.
12 Amp Surge / 10 Amp Continuous.
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Old 06-20-2018, 1:48 AM
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Someone with some technical expertise should explain the characteristics of switching/non-switching power supplies in a pinned post so that the less savvy don't buy something that's not going to work. Switching power supplies are marvelous things. They make it possible to create cellphone battery chargers smaller than an acorn, and are produced in the billions, but they contain oscillator circuits that kick out lots of RFI due to the rapidly switching transistors that control the output voltage. Noise suppression is not a big part of the design brief, since these things are built for literally pennies.
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Old 06-20-2018, 10:14 AM
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I'll take a stab at an explanation, but no guarantee my thoughts will get typed as they should.

For starters, to move voltage up and down without complicated circuitry the voltage has to be AC to work with a transformer. This dates back to when Thomas Edison first wired up cities to run lights and motors in the late 1800s.

A linear power supply has a transformer to change the typical 120V AC line voltage to something lower (for a 12V model) but a little higher than needed for the designed output of the power supply. Then the lower AC voltage is rectified into a pulsating DC, filtered with capacitors and sent to an electronic linear voltage regulator that keeps the final voltage fixed even with slightly varying AC line input and voltage drop within the power supply components under high current use.

There is nothing in most linear power supplies that would create any RF noise in the process of taking 120V AC down to a lower DC voltage. There are also unregulated versions of a linear power supply that simply use a transformer, rectifiers and filter capacitors to provide a DC voltage, but that voltage will drop some as you draw more and more current from the unregulated supply. That might be ok for charging a battery but not for sensitive radio equipment.

At the 60Hz line frequency used in the US, the transformer must have a lot of inductance to work properly and the core of the transformers are made of steel and are large and heavy. If you could raise the AC line frequency, the physical size and weight of the transformer can be much smaller and at some point lighter weight materials other than steel can be used like ferrite. 400Hz line frequency is common for some military and aircraft power and 400Hz power supplies are tiny compared to the same equipment that runs on 60Hz due to the much smaller transformers needed at 400Hz.

Enter the switching power supply. For a typical consumer switching power supply that converts 120V AC to a lower DC voltage like 12V, the power supply first and simply rectifies the 120V AC line voltage to DC and that typically ends up around 170V DC after rectifying and filtering.

But we need AC to use a transformer to change the voltage around in an efficient way, so the DC is made into a crude form of AC using a chopper circuit that might operate at a few hundred Hz or a few thousand Hz or even up to several MHz. This chopper circuit and the resulting square wave AC is full of RF interference that is hard to get rid of.

Now the dirty square wave AC is fed to an appropriate size transformer for this new high frequency, which can now be the size of a golf ball or smaller (instead of a grapefruit or cantaloupe for 60Hz), then more traditional voltage regulators can be used to keep the end voltage constant. Filter capacitors can also be much smaller at the high switching frequencies due to less capacitance needed to to the job. The end result is a power supply that can be 1/10th the size and weight of a linear power supply that does the same job.

Switching power supplies will have RF filtering at both the input and output to try and keep RF interference generated in the switching process from leaking back into the AC line or the DC output, but most are not filtered enough to work with sensitive radio equipment. When shopping for a power supply for radio use, you have to make sure its designed and rated for such use and it will have adequate filtering to keep RF interference to a low level.






Quote:
Originally Posted by guyonearth View Post
Someone with some technical expertise should explain the characteristics of switching/non-switching power supplies in a pinned post so that the less savvy don't buy something that's not going to work. Switching power supplies are marvelous things. They make it possible to create cellphone battery chargers smaller than an acorn, and are produced in the billions, but they contain oscillator circuits that kick out lots of RFI due to the rapidly switching transistors that control the output voltage. Noise suppression is not a big part of the design brief, since these things are built for literally pennies.
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Old 06-20-2018, 12:16 PM
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That's a pretty good explanation of the differences of linear and switching power supplies. I kind of suspect that some ones going to question about that 170 volts.
That is going to be the RMS (Root Mean Square) of the 120 volt line. The RMS of 120 volts is going to be:
120 x 1.414 = 170 (actually 169.68). The 1.414 is the RMS which for 120 volt line has a "peak" value of 170.
I added this for those who may want to experiment building a switching supply (or some other circuits as well). Why? Because a circuit may need some electrolytic capacitors and you have to apply that peak voltage for the amount of voltage going into the capacitors.
PRCGUY gave a great explanation and I hope that will help some of the members understand the differences.
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