In article ,
dxAce wrote:

Lucky wrote:

wrote in message
oups.com...
From: craigm wrote (in part:

There is also the belief that removing the heat generated by a supply
by
using an external supply improves the reliability of the radio.
However,
I have only seen anecdotal evidence to support this.

Aside from reliabiltiy issues, the main reason I run my R2000s and
other radios from an external supply is to reduce heat, which leads
to reduced heat. The radio exceeds it specified stability when operated
from a external power source.

Many built in supplies, and most aftermarket power supplies can be
much noiser then many here would believe. With a decent battery
powered receiver, make a noise probe, I use 10' of RG174 with a 10
turn coil at the sensor end and connector to fit the radio. Please
be certain to use insulated wire and have all he solder connections
covered. I used "liquid tape".

With the radio or external power supply to be tested move the probe
around the supply, over the AC mains input an DC output. For some
reason very few companies include the very usefull ~1000pF caps
across each diode in a bridge. This cap can really help quiten a noisy
supply.

The probe is also usefull to find noise leaks from a PC/monitor.VCR
etc. I use a DX398 because A:It is a smal,sensisitve and easy to use
receiver, and B: I own one.

My main +12V DC supply is a Lambda 12V 20A linear supply, my
backup is a 12V 8A Lambda linear. Both were much quiter then the
often touted and extremly popular Astrons. After a few additions,
feritte beads on the input/output to the bridge, 100pF micas with
very short leads across the bridge, 1000pFs across the junctions
in the pass elements, some 1uF tantalums added across the 723,
the noise was gone.

For most of us, including me, the minor noise from a decent power
supply, either internal or external, is way below the local noise
floor,
but while these mods may be waste for operation ~50MHz, they really
helped remove some noise from my NOAA APT weather satellite
reception. But even on HF during some early morning quite times,
I think the lowered noise helps. And with the borrowed AR7030+,
it is clear that with a good (quite) enough receiver all the noise you
can reduce is well worth the extra effort.

I will only have the AR7030+ for about a month, so I will be listening
a lot more then posting.

And the stock wall wart suplied with the AR7030+ just sucks.
Very noisy.

Terry


Hi Terry

I have a Lowe 150 and I'm using a crappy Radio Shack 12v 500mA wall wort.
I'd like to purchase a Lambda PSU.
My question is this.

Is it safe to use a 12v 3A PSU with the my radio even though is only
requires 500Ma? In other words the excess potential Amps won't fry the
radio?

Can you recommend a certain model Lambda for my radios? I also have a Icom
R75 and some others.

I'm thinking even though the PSU can put out 3A or even 20A, the radio will
still only draw 500Ma and it will be safe?????

Yes, it will be safe. The radio will draw what it will draw.

Under normal circumstances yes but for a failure of some kind that can
draw more power so you should use a fuse. The fuse should be near the
supply end in case of a short in the cord.

--
Telamon
Ventura, California