Powering 396XT from USB

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davef3138

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Has anyone tried using a DC-DC voltage converter such as this DC DC 100W 3 35V 12V to 3 5 35V Boost Step Up Module Power Supply LED Voltmeter | eBay to power a 396XT? Has anyone measured the powered-on, non-battery-charging current draw for the DC input jack?

My goalis to power it from USB, since it's almost exclusively on control channel decode duty connected to a laptop. (I understand that the radio needs 6 volts DC, while USB supplies 5).

-Dave
 

Vermonster

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I have also been interested in this approach. I have purchased a similar buck-boost converter that I want to test on a logging meter before I risk attaching to my 396XT. I don't have a ton of trust in cheap Chinese electronics.

One thing to keep in mind is that the USB 2.0 standard only requires a port to supply 500mA. The 396XT requires 800mA. I'm not sure it every really draws that much unless charging the batteries while running, but it probably comes close. In addition, you will need to supply sufficient current to offset the efficiency of the converter (guessing at about 80%). My approach to this issue is to use a USB A Y cable that combines two USB ports into a single port. These are often sold for powering external hard drives; one example is Amazon ASIN: B00NIGO4NM.

Not sure when I will get around to this project. When I do I'll post back to this thread.
 
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DaveNF2G

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Beware of using USB power under Windows 10. Evidently the Win10 USB drivers instruct the controller to limit the amount of power available at the ports, which limits the number of USB devices that can be used without an externally powered hub.
 

davef3138

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Ultimately, I might not even be using a laptop for the control channel logging or powering the radios. I've ordered a serial logging device which is also USB powered. [ see related thread at http://forums.radioreference.com/vo...21749-serial-data-logger-396xt-cc-output.html ].

So basically I should be able power the entire setup (436hp for voice logging, 396XT for CC logging, and serial logger) with a single multiport USB charger.

-Dave
 

Voyager

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It doesn't specify receiving or not or volume level. But, it's a decent bet the scanner doesn't draw more than 400-450 mA when not charging. That allows for about a 90% efficiency of the adapter.

All in all, it would be close.
 

davef3138

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After a few days of testing, this setup appears to be working flawlessly. I had ordered the device mentioned in an earlier comment.

I don't have the capability to measure the current be drawn, but the input voltage (USB side) only drops a tenth of a volt when the scanner is connected, and the output side seems to be rock solid at 6 volts. The heatsink on the device doesn't appear to warm up at all.

-Dave
 
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DaveNF2G

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I made another discovery about USB ports yesterday. I found that the ports on the front of the computer are slower (8.5 MBPS) than the ones on the rear panel (10.00 MBPS) on a HP Elite 8200. YMMV, obviously.
 
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