Re: [Xylo-SDR] RFC - Powers

["Ahti Aintila" <ahti@attocon.com>]

Due to the international electrical safety and electromagnetic
compatibility regulations (UL, UR, CE, FCC, etc.) I prefer 13.8 V DC and
a separate UL/CE approved power supply for the 100 - 240 V, 50 - 60 Hz
wall outlet connections. Only very quiet switching power supplies are
acceptable, otherwise use bulky linear regulated equipment.

Be extremely careful with shielding and filtering, if you have to use
switching regulators inside the box. Leon is right, generating the low
voltage logic power directly with linear regulators from 13.8 V DC
certainly will heat up the small box too much.

73, Ahti OH2RZ


----- Original Message ----- 
From: "KD5NWA" <kd5nwa@cox.net>
To: "Xylo-SDR Discussion" <xylo-sdr@lists.ae5k.us>
Sent: Monday, January 16, 2006 2:15 AM
Subject: Re: [Xylo-SDR] RFC - Powers


+5V, +- 13.8V

Three scenarios, #1 is the most practical,  when
you try to do too many things it cost too much.

Scenario 1

Input power source is either 13.8V or 110V-220V
power cord, using a switcher to generate all power.

The +5 at 5 to 8 amps, logic power, can be used
in a card when 3.3V is required.
The +13.8 2 to 3 amps used with local regulation
for op-amps. Raw power for a modest amplifier.
The -13.8 at .5A or less, very little power
needed, used mostly with op-amps that use +-
power, local regulated to a lower voltage for noise consideration.

Scenario 2

+13.8 is the input power source, desire to have
fairly high power out from an amplifier.

The +5 at 5 to 10 amps, logic power, can be used
in a card when 3.3V is required.
The +13.8 5 to 10 amps used with local regulation
for op-amps. Raw power for a amplifier.
The -13.8 at .5A or less, is derived from the
+13.8, very little power needed, used mostly with
op-amps that use +- power, local regulated to a
lower voltage for noise consideration.

Scenario 3

Power supplied by wall outlet (110V-220V) using a switching power
supply.

High fidelity audio modes desired, running RF final at 28Volts.

The +5 at 5 to 10 amps, logic power, can be used
in a card when 3.3V is required.
The +13.8 5 amps. Used to power op-amps with
local regulation, raw power for power amplifier.
The -13.8 at 5 amps ,  very little power needed,
used for op-amps that use +- power, local
regulated to a lower voltage for noise
consideration. Used for power output stage to run
on 28V for higher efficiency, better quality RF in voice modes.