Radio Question

You mihgt want to do a net search on "active antennas".

Some of the simple 1 JFET designs work pretty well.

If you Eamil my r2000swl@hot... account I will try to dig one from Monitoring Times, scan it and send it to you.

It is nothing fancy, but with an 18" antenna it will work.

Terry

Whatever you use, the antenna will have to be outside of the metal RV. Make sure the long wire is insulated. A single strand, insulated conductor, run around the perimeter of the RV is about as good as you can do. Even though it is insulated, the antenna should be on short standoffs of some sort, of an inch or 2 or 3, away from the metal roof. You should be able to run an antenna of some 20 feet or more by stringing it around the perimeter. Don't get carried away with length - 20 feet should be adequate.

Bob Swinney

Broadcast stations and shortwave are vertically polarized.It would behoove you to go vertical as a first choice,horizontal second.From memory I believe there is a 50 per cent drop if a station is broadcasting vertical and you are receivng horizontal.

Gunner,

Find some thin magnet wire, e.g. #28 or smaller enamel coated. Use that to make a long wire antenna, it will be nearly invisible. The main rule for this type of antenna is "longer and higher", so do what you can.

Maybe you can add some thin sticks (fishing rods?) at the corners of your RV, and use them to support a long wire or loop a few feet above your roof.

If you can electrically isolate your TV antenna mast from the RV, you can use that as a vertical antenna. If the mast is non-conductive, attach some wire to it. Are there any height limits on the TV antenna mast? Taller is better.

Lots of hams operate from RVs using fold-over or crank-up antennas and masts. Antenna goes up when you're using it, and disappears when you're not.

There are a lot of options, if you think creatively. Many hams operate from RVs and antenna-restricted apartments, condos and developments. Check ham sites

and rec.radio.amateur.antenna for ideas.

Your interference problem will require some work to solve. First, get an antenna outside, connected to your receiver by coax. That should help a lot. Make sure your computer and peripherals are well shielded, cases properly closed and screwed shut. You can add RF filtering (inductance) to cables by wrapping a few turns of the cable around a chunk of core material - ferrite torroids are best, but any chunk of steel will do. Radio Shack and others sell cores for that purpose. Add the cores to every cable exiting your computer, as near to the device as possible. You may need to add shielding around your monitor (conductive mesh, grounded).

-Ron

HF signals aren't polarised any more by the time they get to the receiver. Polarisation is only really important at VHF and above. Radio amateurs use both horizontal and vertical antennas on HF without polarisation effects.

Leon

Are you allowed to have a clothesline?

Sounds crazy, but it has been known to work!

Jim

Yes, this is known as "category 1" network wiring. Seriously.

Jim sez: "Sounds crazy, but it has been known to work!"

Not so crazy, Jim. In the early days of telephony, sometimes single 'phone wires were run as the top strand of fences, with the other side grounded, of course.

Bob Sw>

The classic party line. I lived in a place like that for a while.

Single wire that went up the canyon, with about ten parties on it.

Everyone had their own ring.

In some areas they used harmonic ringing, and they would play tricks like polarized ringing, and ringing from one side or the other of the line, to ground - if the service was a pair.

Jim

Mount a ball and spring mount to the side of the RV, the same way you would mount a whip antenna to any car. Using 2 inch PVC pipe (about 18 inches long, end caps, yada, yada), some #10 mag wire, a bunch of threaded fittings, etc..and of course an old 102" whip.. Build yourself a tunable texas bug catcher antenna. Basiclly you'll have a

102" steel whip mounted on your HOMEMADE RF TRAP, mounted to the RV just like any old CB antenna.

Google "Texas Bug Catcher antennas" for ideas.

Another option would be to build a wood frame in the shape of an X, wrap the frame with about 20 feet of bare coppper wire (you are building an active X antenna) Simply set you frame on the roof of your RV and turn the antenna till you get the direction you want. (in fact, this maybe your best choice because you can center the antenna on the roof, the roof will act as the ground plane).

Here's one I had bookmarked:

Google "Homeade SWL antenns" and "low profile antennas" also there is a book called "low profile ham radio" I forget who wrote it, but it had tons of hidable antenna plans for SWL.

n.

Thanks in advance

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

Hummm interesting. Ill check

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

While I thank you for the link (one Id already followed during my investigations)...i did make this comment in the original post.

Im sure you are aware that Im quite good at research on the internet, and did a fair amount of that, before posting my question. But there are often tricks that individuals have come up that might be appropriate

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

How about one of the flagpole antennas?

In Message-ID: posted on Tue, 05 Apr 2005 10:01:20 GMT, Gunner wrote: Begin

For the antenna: Sony AN-1 (looks innocuous like a car antenna) For the noise: Timewave ANC-4 Not sure what your ambient RF level (KNX etc.) is at that location, but maybe a pre-selector would allow for weaker DX stations. I have an old Grove TUN-4 but I don't' think he still markets it. Some active antennas include a pre-selector.

In Message-ID: posted on Tue, 05 Apr 2005 16:16:13 GMT, Gunner wrote: Begin

It's such a common old ruse that maybe no one thought to mention it, but the PVC flagpole (wire inside) might be a go if you fly the appropriate flags from it.

Antenna matching is only for extremely challenging receiving (which this is not), or for transmitting.

Unless your radio is real crap you'll be receiving atmospheric noise in excess of the receiver's internal noise with even a moderate antenna. Atmospheric noise drops off at the higher frequencies, but the antenna effectiveness will increase for a moderately - sized antenna. If you really want to disguise what you're doing then mount the TV mast with insulators, put in a good radial grounding system, and use the whole TV mast as an antenna.

This scheme requires that you either build a diplexer to isolate the TV coax outer shield from ground at the lower frequencies or disconnect the TV when you want to listen to SW. The former will be moderately difficult but not insurmountable -- I think you could do this with a 1:1 RF transformer and some dinking. The latter will be easy but inconvenient -- but you can always start with the connection method and build the transformer later.

The ARRL sells a book on low-profile and hidden antennas. You can go to

for more information, or see if there's an amateur radio supply store near you. They also sell books on reducing EMI, which may help with the computer.

That's what they had up the canyon I think. Everyone was on one line. A pretty remote area. I don't think it was fence wire though, it was copper.

Jim