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power for qrp-labs dds

 

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

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Art,

I built a small board with a 7805 on it.? Haven't tested it yet.

73,? George


On 1/23/2017 6:15 PM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

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Use a 5 volt 3 pin regulator, powered from the 12 volt rail?


On 24/01/2017 11:15 AM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
M Garza
 

Hi Art,
What is wrong with using a 7805 to provide the 5 volts?? It should not create any noise.

Marco - KG5PRT?

On Jan 23, 2017 6:15 PM, "Art Olson via Groups.Io" <olsonaj6927=[email protected]> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

开云体育

Great suggestions. Will give it a try

Thanks

Art

Sent from my iPhone

On Jan 23, 2017, at 7:42 PM, M Garza <mgarza896@...> wrote:

Hi Art,
What is wrong with using a 7805 to provide the 5 volts?? It should not create any noise.

Marco - KG5PRT?

On Jan 23, 2017 6:15 PM, "Art Olson via Groups.Io" <olsonaj6927=[email protected]> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

Art,

I am assuming you are building your own;

?

I used an LM7808 ?(8v) regulator into the Nano (Arduino), and use the 5v out of the Nano to power the DDS /LCD (if you're building your own)

?

I have also used these successfully to help eliminate noise;

http://www.xppower.com/pdfs/SF_IV.pdf

to power a noisy OLED display - but they are not cheap and you need to be aware of your power requirements.

Rgds,
Darryl

?

?

On 2017-01-24 11:15 AM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

I just used a 7805 regulator connected to 12v. Works fine so far. Yes, you lose a little power in heat, so it's not as efficient as a buck converter, but I don't consider it an issue for my use.

Hope this helps!

Ryan KC7RYS
Jack Purdum
 

Hi Ryan:?

I think that's my next step. The buck converter worked fine on the Forty-9er, but I think this receiver is more sensitive.

Thanks!

Jack, W8TEE


From: Ryan Flowers <geocrasher@...>
To: [email protected]
Sent: Tuesday, January 24, 2017 1:56 AM
Subject: Re: [BITX20] power for qrp-labs dds

I just used a 7805 regulator connected to 12v. Works fine so far. Yes, you lose a little power in heat, so it's not as efficient as a buck converter, but I don't consider it an issue for my use.
Hope this helps!
Ryan KC7RYS
 

You don't need a buck converter just a 7805 regulator or its lower current sibling 78L05 with input 12V ,output 5V with both up- and down-stream capacitors (electrolytic and ceramic)? to prevent possible oscillation.

On Tue, Jan 24, 2017 at 8:15 AM, Art Olson via Groups.Io <olsonaj6927@...> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

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Frank

Building one today - thanks for your help
73
Art

Sent from my iPhone

On Jan 24, 2017, at 10:44 AM, Frank Dinger,GM0CSZ <gm0csz@...> wrote:

You don't need a buck converter just a 7805 regulator or its lower current sibling 78L05 with input 12V ,output 5V with both up- and down-stream capacitors (electrolytic and ceramic)? to prevent possible oscillation.

On Tue, Jan 24, 2017 at 8:15 AM, Art Olson via Groups.Io <olsonaj6927@...> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
 

You can use a 7809 or 7808 before the 7805 to spread the dissipation in each regulator.
Lawrence
 

Or put 2x 7805 regulators in parallel ; I have done that for a router for which I did not have the 7.5V power supply unit ,fitting 2 x 7808 regulators in a small aluminium enclosure ; after 5 years still operational without any problems.

Frank? GM0CSZ / KN6WH


On Tue, Jan 24, 2017 at 4:41 PM, Lawrence Galea <9h1avlaw@...> wrote:
You can use a 7809 or 7808 before the 7805 to spread the dissipation in each regulator.
Lawrence
 

Ive used the mini360 dc to dc converter to power a vfo 12v down to 5v. Seems to work ok but it use it as an outboard vfo so not in the box with the radio.

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