In article
. rogers.com,
"Peter" wrote:

"David" wrote in message
...
The 13 Volt input connects (through a diode) to the DC rail in the
Power Supply, upstream from all the regulators, downstream from the
full wave bridge. It is always connected.

The regulators would draw power from both the AC/transformer/bridge
and from the battery/diode if both were hooked up.

On Wed, 26 Nov 2003 21:06:54 GMT, "Peter"
wrote:

I have a question about this radio. If I plug the AC jack in the
wall and I have the 12 volt connection
hooked
up to a battery as a power failure backup will it damage the
radio? Is
there
an internal switch to protect it from both sources being connected
at the same time?

I got a response from Drake this morning. Here it is:

"There is a diode switch to protect each area so there should be no
problem. Shane "

I tried it and it seems to work fine.

The diode would make it safe to connect the battery to the DC terminals
with the internal AC supply operating.

What will determine if current from the battery is drawn while the AC
supply is operating are the voltages of each at the diode-summing
junction since there is no current share connection between them.

If the battery voltage is even slightly below the AC supply voltage no
current should flow from the battery and at the same time the internal
AC supply can't recharge the external battery either so to keep it
charged you will need an additional external AC supply.

As soon as the internal AC supply voltage falls below the battery
voltage then current will be drawn from the battery.

--
Telamon
Ventura, California