Radio Question

Gunner wrote:


Others have answered the antenna part. As for the connection, you want good-quality coaxial cable, with the shield terminated well at the receiver and at the place in the RV's wall where it passes through. This effectively places the entire receiver "outside" the RV, as a shield wall completely surrounds the receiver (you hope) and is then carried out through the shield of the cable. This is how it is done on aircraft, which are also pretty horrible EMC environments inside the fuselage. You may have to put a line filter on the power plug to the receiver to keep computer hash from sneaking in on the power cord.
Jon
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Gunner, can you get away with a CB antenna? You really don't need a lot of antenna for SW reception, a moderate sized mirror mount whip should work pretty well & I'm sure you wouldn't be the only one in the park sporting one.
Howard.
wrote:

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On Wed, 06 Apr 2005 00:23:42 GMT, Howard Eisenhauer

Actually..the only one in this park is on my truck. I do have a spare K40 48" whip somewhere around the homestead, and Ill dig it out this weekend and make up a mount and run some coax and give it a try.
Im sure Im going to need a power line filter though. The radio may be run off 12vt dc, or line, or 8 D batteries. I may simply use a DC supply and see if that kills some of the noise from the puter.
Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"
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Wed, 06 Apr 2005 03:58:29 GMT, Gunner wrote: Begin

Don't get your hopes up, puter noise is airborne (RF), IOW comes in through the antenna. Read about that phase inversion box I mentioned (ANC-4) http://tinyurl.com/5mfjz
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Bart

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wrote:

I had the same problem with my PC, I could pick up noise all over the house, especially bad below 4-5 MHz. I put ferrite cores on every power cord I involved with the PC & the radio as well & that improved it quite a bit. later on I replaced my CRT monitor with a LCD & now the problem seems to be gone all togeather :). YMMV.
H.

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Also follow the instructions about bonding the coax as it exits the RV shell.
Because the metal skin is a good faraday shield as you say, it will keep the rf noise from getting *outside* where the antenna is. So all you need to do is make sure that the rf does not ride along the sheild of the coax and get to the antenna. By bonding the shield (stopping off at a bulkhead fitting) to the skin, you prevent this.
Jim
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wrote:

I don't know if this would work or not, but it's certainly stealthy. It depends on the RV not being grounded to RF. If it is grounded to the utility, an RF choke in the ground line would fix that: just a few turns of #14 on a large ferrite toroid. I can send you a toroid.
Think of the RV itself as a fat whip. It is certainly more than 4 feet high. It will have a large capacitance to ground, but a whip is just a capacitive E-field probe and radiation resistance for short antennae is very very low.
For "ground", you then create a counterpoise on the ground under the RV. It could be a length of wire, radials, or even chicken wire. It is out of sight and essentially invisible.
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There's a business idea, the "Mobile Home" mobile antenna. Better get your trademark filed.
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If you see an op here, feel free to pursue. I'll say again that I don't know if this would work or not.
Theory can be very useful and I use it a lot, but proof is when ideas are tried and found to work or made to work -- or found not to work with experimental evidence that clearly shows the idea is flawed and should be scrapped. The latter case is progress if the experiments were done well because it serves to focus energy forward. The trick is to persistently pursue good ideas while drowning the weak doomed pups ASAP. Popular opinion (as from marketing pukes) can be the worst possible gage for such decisions.
I'm a retired research puke and prolific inventor with I forget how many patents, all assigned to corps who care about such truck. I don't own any and don't want to own any. Inventing is easy, converting inventions to money is work and defending patents is expensive.
I retired to fart around and I'm enjoying the hell out of it. I'm in give-back mode now. I'm also in NIU (nothing is urgent) mode. I can still get urgent for those that care to pay me enough to get me off me enjoyably indolent retired arse, but that doesn't happen much. I didn't book 200 hours last year and I expect to do somewhat this year. Gone fishin'. Iceout is imminent in MN.
I have a ground wire RF choke toroid sitting here on the bench with Gunner's name on it. It's 48 mm OD, 35mm ID, 9.5 mm thick. Jerry Martes sent me several such ferrite toroids and I'm glad to share. I'd even pay postage because I'm curious to see if this would work. I think it might, but I don't have an RV to try it with.
I expect that Gunner will find field-expedient quickfix.
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Would the park allow you to have a patio umbrella? Maybe you could attach a loop antenna to the underside of it. I wouldn't be surprised if you could get away with a 20' square umbrella.
Pete Stanaitis
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On Tue, 05 Apr 2005 23:22:56 -0500, Pete & sheri

I'm quite sure that gunner had to block up his RV and remove the wheels/tires to:
A) keep his RV from getting stolen
B) keeps his RV's wheels and tires from getting stolen.
How long do you think gunner would remain the owner of such an umbrella ? Minutes ? hours ? day or two ? Remember the universal trailer park law "If it ain't inside, it ain't yours (anymore)"
n.
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Or the variation: If it ain't nailed down, it's mine, and if I can pry/jackhammer/chainsaw/hoist/dynamite/otherwise get it loose, it wasn't nailed down" :)
--
Don Bruder - snipped-for-privacy@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
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On Tue, 05 Apr 2005 23:22:56 -0500, Pete & sheri

OOOOO...sneaky!
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error"
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Just get a big wire, connect it to your rig and throw it into a tree (if one is nearby your RV)
This is what I do at home and I hear all kinds of stuff...
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wrote:

Trees?
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error"
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In Re: Radio Question on Thu, 07 Apr 2005 06:02:56 GMT, by Gunner, we read:

You've gotten some good suggestions.
To meet your conditions for AM and SW its hard to beat the rooftop horizontal.
Use 18 gauge multistrand copper antenna wire (Radio Shack), or copper covered steel core cable, around the perimeter. Do not use lamp cord or just any insulated wire lying around for an antenna.
The antenna must be mounted on insulated standoffs and as high as practical.
Bring both ends of the antenna to separate standoffs above the window which will take the leadin wire.
Solder one end of the antenna to the center wire of a 59 ohm coax and the other end to the coax braid. Insulate. Bring the coax down to the window and inside.
Mount a multibus electrical connector (Home Depot) to a short piece of 2x4 and affix near the window.
Ensure adequate length of coax to the radio and cut. Solder the coax to a 259 female connector. Connect to the radio. Run 16 gauge copper solid from the radio ground to the multibus and run a separate 14 gauge solid copper wire from the multibus out the window and down and properly afix to a 8 foot ground rod driven into the ground.
That's a loop antenna. For experimentation you could leave one end of the antenna open on the roof and run the other through the center coax as before. That approximates an end fed short wire antenna. Another configuration is a dipole.
The 18 gauge multi strand antenna wire will be broadbanded and give you a bit more signal. Of course ground wire should always be heavy.
Now solder 14 gauge copper to the computer box and the monitor frame and run to the same multibus ground connector.
Use at least two ferrite loops on each AC line cord in the trailer; one near the AC wall plug and the other close to the input of each appliance. I would also take ferrite doughnuts and loop the AC cords through it twice.
I would also ground the trailer frame. At least six feet deep in that sand and pour in some water for good effect.
To minimize noise you could run the radio off a battery or use a standalone UPS. This would also be additional filtration for the computer and the radio.
Now you have a real antenna and a real ground and you've grounded eveything in the trailer.
Additionally you can use an in-line signal amplifier for AM and SW.
For signal above 25 mHz, use a vertical antenna, simple or fancy. Since you only need a 1/4 wave, 130 inches will handle 11 and 10 meters. Height is important here. Mount a telescopic mast to the side of the trailer and use the same leadin and ground methods as before.
For the rooftop antenna you can build a 2x4 frame and attach the standoffs to it. Or construct a 2 inch PVC pipe frame. Run the antenna on the outside of the pipe.
All you need now is a Drake or Icom receiver and you're in business.
A piece of cake.

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To obtain the (folded) dipole, break the antenna conductor midway between the feedpoint.
Jim
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This is a multi-part message in MIME format. --------------010900030005020903040003 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit
Gunner wrote:

Well in the case of Taft maybe you could use oil derricks instead of "trees".
When I was there 40 or 50 years ago they were all over the area. Probably all gone now.
Bill K7NOM
--------------010900030005020903040003 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> Gunner wrote: <blockquote cite=" snipped-for-privacy@4ax.com" type="cite"> <pre wrap="">On 6 Apr 2005 12:38:48 -0700, "STATE MILITIA" <a class="moz-txt-link-rfc2396E" href="mailto: snipped-for-privacy@space.com">&lt; snipped-for-privacy@space.com&gt;</a> wrote:
</pre> <blockquote type="cite"> <pre wrap="">Just get a big wire, connect it to your rig and throw it into a tree (if one is nearby your RV)
This is what I do at home and I hear all kinds of stuff... </pre> </blockquote> <pre wrap=""><!----> Trees?
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error" </pre> </blockquote> Well in the case of Taft maybe you could use oil derricks instead of "trees".<br> <br> When I was there 40 or 50 years ago they were all over the area. Probably all gone now.<br> <br> Bill K7NOM<br> </body> </html>
--------------010900030005020903040003--
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wrote:

Ayup. A very few still standing. The wooden one at the Oil Museum came down in a strong wind storm last year.
But..we can count pump jacks.
Gunner
Rule #35 "That which does not kill you, has made a huge tactical error"
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Run the reciever off the TV antenna?
I had a cell phone one time, which had a screw connector. I got a mobile mount antenna, and stuck it to the window AC. Ran the wire inside. Worked well.
Can you run a vertical wire parallel to the lead in wire from the roof antenna? I remember a recipe for a vertical coaxial ground plane, folding the shield back over the black plastic.
But, that was for TX. Perhaps a RX antenna would be more forgiving.
Just thinking a bit here, nothing that I've tried and had succeed.
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Christopher A. Young
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