Re: uBITX V6 heat sink temperature

bill richardson

My V6 at the power plug is seeing 350ma. This is more than double my V5 with the standard display. It would be nice to be able to turn off the display to save on current draw. It makes the new V6 not so portable for the folks that like to run on minimal current when portable.

On Dec 30, 2019, at 9:13 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

I believe Joel is talking about the LM7805 regulator on the Raduino.
The LM7805 is spec'd to continue working at temps as high as 150 C.

I have no idea how hot it should get on a v6 with the new display, but on the older uBitx's
the Raduino typically drew around 60ma from the 12v supply.
So about (12-5)*0.060) = 0.42 Watts dissipated as heat in the LM7805.
They figure the part rises about 19 degrees C per watt to be dissipated above the ambient air,
so 60 C does seem kind of high.  But it's not about to burn up.

Would be interesting to hear reports about how much current the Raduino on a v6 draws.

Some of the Nano's on the Raduino have been found to draw more current than others.
Some uBitx owners felt the LM7805 was way too hot, and put a heatsink on it.
The Raduino should get just as hot during receive as during transmit.

Jerry, KE7ER

On Mon, Dec 30, 2019 at 04:26 PM, Alex Netherton wrote:
Wow, when I have my SB-200 just turned on, it heats the room. When I in a long QSO, I have to open the window!

Warm finals are just a fact of life.If you are running Class B, your duty cycle is 50%, meaning that you are feeding the transistors with 20 to 25 watts, dissipating around 10 watts (or so). This will indeed heat up the heat sink, but most JFETS are rated for such temperatures. If the transistors are biased for Class AB, then you are likely putting close to 30 watts in to get 10 out.
Just put a hot dog on top of the finals!
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On Fri, Dec 27, 2019 at 12:11 PM Joel Caulkins/N6ALT <caulktel@...> wrote:
Hi all,

I have my V6 all hooked up and calibrated and have checked into a few nets with my own home brew mic, the supplied one got bad reports, however I have noticed that the 5 volt regulator heat sink is running at 142 degrees F or 61.1 C. That seems hot to me. Anyone else?


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