Re: minimum supply voltage

Howard Fidel

Put a DC to DC converter between the battery and the uBitx.

On 4/25/2018 5:17 PM, Jerry Gaffke via Groups.Io wrote:
7v min for the 7805 on the Raduino is about right.
Most of the uBitx analog circuitry will probably be more or less working at 7v, but I don't really know.
It was all designed with 12v in mind.
I doubt you will get much RF out of the transmitter at 7v.
Some have reported hearing signals from the receiver with power off while the Raduino is connected 
to a USB host for downloading firmware, the host's 5v going back through the Raduino's 7805 to run the receiver.

15v is the absolute max spec for a good TDA2822.  (The WX clones can explode at 10v)
But at 15v the 7805 and some transistors and resistors will be getting hotter than they should.
If using with a battery pack that might exceed 13v, I'd recommend including
a low dropout regulator such as the LM2940-12 to power the main uBitx board (but not the IRF510's).

On Wed, Apr 25, 2018 at 01:35 pm, Jack Purdum wrote:
I think the Nano wants to see 7V or more on its regulator. I know I saw that somewhere, but I've slept since then...

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