Hi,

I need broadband (2MHz - 30MHz) receive-only capability. I will be
connecting the antenna to a system that can stare at 10 MHz of RF
spectrum simultaneously. I have very limited space and almost no
antenna experience.

I've been told to look for a loop antenna. I stumbled across the
MFJ-1024 active antenna.

What's the best choice for my application? I want to hear very weak
signals.

I have limited time available to do the install. I'll gladly spend more
money to have less hassle and a greater probability of success.

John

A simple wire antenna will do as good a job on the hf frequencies.
Simply run a length of thin wire around the perimeter of the largest
outward facing window and attach to your receiver. Suspend it with
mini suction-cup hooks.

Or, run a length of wire around the perimeter of your listening room.
Just tuck it between the carpet and wall and nobody will be the wiser.

Thin multistrand wire is the best choice, and you can even use really
thin magnet wire for the window antenna.

The Wellbrook loops are broadband and very quiet. Bring money. I use
the ALA100 and a homemade wire loop. The other models come with loops,
but are less flexible.

Long wires pick up lots of man made noise. I think those vertical whips
plus amp like the MFJ1024 are worse than a long wire.

wrote
Hi,

I need broadband (2MHz - 30MHz) receive-only capability. I will be
connecting the antenna to a system that can stare at 10 MHz of RF
spectrum simultaneously. I have very limited space and almost no
antenna experience.

I've been told to look for a loop antenna. I stumbled across the
MFJ-1024 active antenna.

What's the best choice for my application? I want to hear very weak
signals.

I have limited time available to do the install. I'll gladly spend more
money to have less hassle and a greater probability of success.

John

You're going to be at odds between your desires and what "very limited
space" is going to allow in the way of antennas. Unless you can get some
form of antenna away from the dwelling, and even better up in the air, very
weak signals are not in your future. If your listening is going to be on a
portable, a 10' window-area wire works fine, and so does the factory whip,
if you're upstairs, LOL. Loop antennas can be very expensive, costing more
than your radio, or cheap, AM Bcst band loops like Radio Shack occasionally
offers. With what little information you provided, its hard to tell what you
really expect, and what your price range for receivers is, or what you are
using.

Jack

John,

wrote:

Hi,

I need broadband (2MHz - 30MHz) receive-only capability. I will be
connecting the antenna to a system that can stare at 10 MHz of RF
spectrum simultaneously. I have very limited space and almost no
antenna experience.

I've been told to look for a loop antenna. I stumbled across the
MFJ-1024 active antenna.

What's the best choice for my application? I want to hear very weak
signals.

I have limited time available to do the install. I'll gladly spend more
money to have less hassle and a greater probability of success.

John

Hi

I really think we need more information about how you define "limited space" and
how much easy work you're willing to do to give you a good answer.

Active antennas amplify everything they pick up including your neighbors lamp
dimmer, your crt computer monitor and possibly any VCR's you might have. If
you're gonna get one, I suggest installing it away from the house.

If one antenna is 10 feet away from a noise source and one is 5 feet from it,
the farther one will get 4x less noise. Change that to 50 feet and 5 feet and
the farther one gets 100x less noise. (square of the distance)

With modern radios, signal to noise level is almost always more important than
signal strength.

Loop antennas are often designed to be tuned for each frequency. If you're
looking at 10mhz of spectrum all at once, you don't want one with this feature.

An advantage loops have is they don't pick up as much local rfi (noise) as most
other types. Dipole antennas are also relatively immune to local noise.

Someone else mentioned the Wellbrook Loop. It's an active loop. I've never
used one, but they're highly respected, and next time I want a "transportable"
antenna with at least a couple weeks notice I'll probably buy one. (you have to
order them from England) It's probably a "safe" choice, and I'd expect it to
out perform the MFJ because the loop won't pick up as much noise as the whip.

But if you can put 30 or more feet of wire 50 or more feet away from the house
with an impedance matching transformer and run coax underground to the house,
that'll probably work well for you too. It's not rocket science, and folks here
can give you all kinds of tips to get it going quickly.

I have a 60' random wire about 225 feet away from the house. It works
incredibly well. Other than getting the trench put in, (I hired someone for
that) it was a one morning job.

For my vacations and camping radio, I use a broadband active whip made with
milspec components. It works well too - but I use it away from devices that
cause rfi.

Good luck.

Mark

The nice thing about the Wellbrook ALA100 is you can use it portably as
well. This is a recording I made of the LAX TIS on 530Khz from about
400 miles away
www.lazygranch.com/sound/lax_530_etgravel.wav
This was with the 4ft on the diagonal loop.

wrote:

Hi,

I need broadband (2MHz - 30MHz) receive-only capability. I will be
connecting the antenna to a system that can stare at 10 MHz of RF
spectrum simultaneously. I have very limited space and almost no
antenna experience.

I've been told to look for a loop antenna. I stumbled across the
MFJ-1024 active antenna.

What's the best choice for my application? I want to hear very weak
signals.

I have limited time available to do the install. I'll gladly spend more
money to have less hassle and a greater probability of success.

John

Loops are directional, as are dipoles etc.
Do you need coverage just in specific directions, or all around?
Are you looking for all signals or just relatively strong ones - i.e. do
you need to get that 10 watt beacon in Norway?
How noisy is your local RF environment?
Are you restricted to an indoor antenna, close to the radio, or can you
remote it 10 feet, 50 feet?
Do you want to prevent anyone else from knowing? or can you put it up in
public view?

Lots of questions, all of which would help make a choice.
There are some very good active antennas, but the good ones cost good.

Dave

Dave Holford wrote:
snip
Loops are directional, as are dipoles etc.snip


Wellbrook suggests a rotator for LW and MW on the 1530, but they don't seem to
call for one for HF.

http://www.wellbrook.uk.com/ALA1530.html

Thanks for your reply.

I have a special wideband (10 MHz) SIGINT radio.

I think I'm going to go for the Wellbrook ALA 300.

Should I sit it on my deck or should I put it up on a mast? My gear is
in my basement.

John