Tip: Effect of Power Sources on the Ham It Up Upconverter

The Ham-It-Up upconverter uses a 5V USB power input. I discovered that different 5v power sources can cause significant interference with this upconverter, and the same effect will probably occur in other upconverters as well.

When the upconverter was powered by mains power via a phone charger, the signals were almost completely drowned out in noise. Powering it with a PC USB port was better, but the PC USB power introduced some other strong noise sources. Powering it with a battery (used a mobile phone with OTG cable) was the best option. There are still some strong noise sources present, but I can probably solve them with better shielding.

Click continue reading to see some comparison images.

Mains Power Supply (Via. Phone Charger)

Power_2

PC USB Power Supply

USB_2

Mobile Phone Battery Power (Via OTG Cable)

PhonePower

7 comments

  1. Gerry Creager

    The issue of conducted emissions is significant. Ferrite will help significantly; bypass capacitors will, as well. An array of small value mica capacitors in parallel across the DC input will help with different frequencies of intrusive RF energy on the power lead.

    However, this is CONDUCTED radiation. While placing the receiver in a metal box will help some, because almost all conducted emissions have a radiated component, if you can eliminate the emissions via blocking and bypass, they won’t radiate in the process. A metal case, with or without ground (earth) will not have a significant impact on results if you do not use ferrite for blocking and caps for bypass.

  2. Stefano

    Hi
    I’m a student of the Faculty of Engineering of Bologna. I’m writing my thesis on a project that uses the USB R820T + ham it UP converter . I would like to ask a question . My ham it up does not have the connector microusb but another type of connector that do not know the technical name . I just know that is identical to the connector that I use to connect my printer. When I give power to the converter and plug in my USB to my PC if I open SDR # , I select AM and put a shift of -125 000 000 switch to upconvert , I put a sample rate of 1 Msps but when i insert the frequency value that I want I do not see any spectrum not only for that value but for whatever frequency and I will not hear anything. My teacher says it could be a power problem , in fact the up-converter need 5V and 3A. My up-converter is connected to an USB HUB with power but with a 5V 2.5A . One other strange thing is this: I see on the oscillator 125 mhz but on the up-converter near X1 I read the number 100 MHz
    Someone can help me ?

  3. Jon

    Those multiple yellow lines you have look familiar. I found mine from a laptop power supply that was generating RFI all over the house. Time to test your circuit breaker and find that offender.

  4. Efcis

    Don’t hesitate to use ferrite clips around the power supply DC cord (or the USB cable), near your dongle, and make several turns if possible. As stated before, a metallic box is also highly recommended. Additional decoupling capacitors can’t hurt too…

  5. marodian

    I highly recommend enclosing the upconverter and rtl in a box as per this older post. http://thisisnt.com/put-it-in-a-box/

    Earthing the box makes a big difference.

    Also removing the shield from the usb cable at the rtl end as per this post makes a huge difference.
    http://sinnet3000.blogspot.com.br/2013/03/reducing-emi-in-rtl-sdr.html

    I have also found using a choke at the rtl end of the usb cable makes a significant improvement.

    I have incorporated all mods and use the rtl with the ham-it-up with very little to no rf interference. If i do get any its usually something local like a monitor. Having a long usb cable so you can locate the unit away from any local sources of rf interference is also a big help

  6. Eugen Sibler

    Your findings are not very surprising: Phone chargers are Switched Power Supplies causing strong RF-interference in the vicinity of the power supply. For HF receivers I strongly advice to either use batteries or Linear Power Supplies (heavier due to the much larger transformer).

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