At HF you must put multiple turns thru ferrites, even the clamp on ones.  Large dia. toroids are useful.  Use high permiablity materials (mu).

Generally the common mode choke will work best at the computer end of the cable vs at the mouse end.

Also try to isolate the part thats vulnerable by experimenting with disconnecting the cables one at a time.

You might also try running the rig from a battery or different outlet to see if there is RF on the power lines.

Best of luck.

It all really depends on how long your "long wire" is.

You need to examine what the current distribution is on it.  Which depends on how you feed it.  

I assume you are actually using a "random" wire length on multiple bands.  Furthermore you are probably feeding it at the end.

If you are feeding it at a high current point, treat the system like you would a 1/4 wave vertical for purposes of matching and feeding.  You need a ground system of some sort.  Most likely radials, with rules similar to what is used under a vertical.  I have faked this for temporary or compromise situations by using the cold water pipes in the house as a ground.  Many times you can find one close by the shack, say an outside water faucet.  You can then mount an auto tuner near the ground point and use it to match the antenna.

Many times I intentionally make the length of wire an even 1/4 wave length multiple such that I feed at a voltage point.  There is then less current at the feed point, and consequently less need for an extensive ground system.  You have then to deal with all the problems of "end fed half waves", common mode etc.  There is a trade off.

One last cheat I have done for compromise installations, is to feed the random wire with the balanced output of a manual tuner.  One terminal goes to the wire and one terminal goes to whatever you want to consider a ground (say a "counterpoise" wire or a water pipe).  You are basically creating an offset fed antenna and trying to use the balun in the tuner as a way to isolate the common mode.  Most times it works well enough but I suppose for some lengths and crappy grounds it might not.  My solution for those sorts of problems is to change the length of the "antenna" wire.  You might also want to note that whatever wire length you use to hook to your phony "ground" has antennna currents and radiates as well.

I think the most salient point is that you should be prepared to fiddle and experiment.  You should not just go by some "rules".  A little review of the basic theory part of the antenna book might not hurt either.

Find a local ham club.  You should be able to find guys who would be able to loan you an old rig and help you with antennas, especially if you are a youngster.

I used to have an old SB102 that I loaned out to new interested hams.  I showed them how to build a simple antenna and they were on the air.

At your age, I remember it was hard to scrape any money together.

Try the Elmer loaner route, you might be surprised.

The CPSC will pry my IC7000 out of my cold dead hand...

Its a great radio.  It's just that its small and draws 20amp on transmit.  So when things fail, its exciting.

Whenever you put something in you car attached to the battery, you need to think about fire safety.

In this case the enclosure of the device is meant to provide a way to contain the potentially flamable parts.

I doubt I would be happy with a crispy radio but its hardly an "fire danger".

You need a variable capacitor in series with the loop to tune it.  I put mine in one of the corners.  The loop is basically a big single turn inductor so the cap must resonate the inductance of the loop.

When the loop is resonated it has a very low impedance because of its small size.  You need to match the feed line to it.

The easiest way I have found, is to build another loop inside the loop that is about 1/5 the area of the main loop.  This forms a single turn transformer and couples to the main loop.  It does not need a tuning cap.  It also works to transform the low loop impedance.  I mounted this loop at the opposite corner from the capacitor.

The coupling loop is fed with coax in series.  Strictly speaking you should have some sort of balun to the coupling loop but in practice you can omit it.

You can tune the main loop by listening on the coupling loop and tuning for max noise and RX signals.  An antenna analyzer makes tuning much easier.

You can also couple loops with gamma matches and ferrite transformers but I have found that to be harder to do.

If you want to transmit on the loop, the voltage on the capacitor will be very high.  Also using wire as a conductor, losses will be high.  For transmitting you need to make the loop out of copper tubing etc.

There is a lot of info on the web about loop construction.  Google is your friend...

I've used them and it can work.  

Consider using an autotuner and length of wire set up as a vertical or inverted L to the tall tree.  It's stealthy and the autotuner can be made to match the wire on many bands.  The fence can provide the ground for the auto tuner.  On the lower bands it will outperform the vertical if the wire is long enough.  Most verticals are heavily loaded below 30 meters.

It has nothing to do with aluminum.  The wet antenna problem most often comes from a material used as an insulator or dielectric.  Most likely a material used as a dielectric, because clean water is a lossy dielectric.  If you have a capacitor in your design or piece of coax used as a capacitor, you start looking there.  Then find a way to keep the water out.

Additionally you need to take the usual precautions about water getting into the coax feed.

GL es 73

too light for anchoring a boat.  Toss'em

go to cebik.com and read his articles about differently shaped dipoles.

Whether it is bent, u shape or whatever, if it is not around 1/2 wave on 80m, it will not be very good.

I also question the PVC pipe as a support, its not very strong and electric fence wire is bound to be stiff and ugly.

you need to rethink a little.  Try to make it a little less ugly.  If you have RFI issues with the neighbors, it will help a lot if they don't think your hobby is ugly.

Yes anything older than about 10years will have obsolete component issues.  That's why you shouldn't over pay for highly rated but old rigs.  You need to discount them for the fact you may end up with an organ donor rig.

Unless you are collecting, or get a good price, stick with stuff that is realatively recent.  Many new rigs are very modestly priced and those several years old should be your best bet.

I wired 10 470ohm 2W carbon comp resistors in parallel using their leads (keep short) on the back of an SO239 connector.  That gives you a 20W dummy load.  You can zap it with up to 100W for a few seconds or a short burst of SSB.

You stack them like cord wood and use the leads as a structure / interconnect.  It has acceptable SWR from DC to about 30MHz.  Cost was low as it was built out of junk.  

You could use 510 ohms to get closer to 50ohms.

If you shunt the Hi Z resistive antenna impedance with a capacitor you get a resulting impedance that has a lower resistive part and a capacitive reactance.  In an L network you then "tune out" the capacitive part with a series inductor leaving the (lower) resistive part without reactance.  My reason for adding the shunt reactance is to help the ATU L network match to the very Hi Z antenna.

You can change the antenna length and it will "work".  I was just answering the question of the poster.

The theory is that if you are anti-resonant (half wave) you have very low ground current in the return path.  There is a certain amount of controversy over whether this is a benefit or not.  I don't really think we want to go there in this post.

I scanned the posts and nobody answered the question directly.

The answer is yes a shut cap will allow it to match high impedances.  I have demonstrated this with my K2 ATU.  Theoretically the L network should be able to match the end fed antenna.  I have built manual tuners that will do it.  However tuning becomes very touchy due to high Q.  

Evidently the ATU tuning algorithm is not able to deal with the very sharp tuning characteristic as it tries to converge to a match.  When you add a shut capacitor to the output, you lower the resistive part of the impedance down which makes the tuning less sharp and the ATU can find a match.  You need to be a little carefull not to add to much capacitance or you will end up with too low of resistive part and efficiency will suffer.  As an aside, I have seen the shunt cap at the output used in ATUs for marine random wire tuning.  Some marine ATUs have a jumper to add a fixed shunt cap at the output to help "problem" matching

I brought this subject of not matching even multiples of quarter wave wires up on the Elecraft list some years ago and got the Elecraft response of "don't use half wave wires".  They didn't seem to feel the limitations were a problem and didn't see any merit in the shunt capacitor solution.

Lastly, if you look at the matching system usually used for the end fed half waves, the tapped parallel tuned circuit, you see it can be decomposed into an analogous pi network which is the capacitive analog of the tapped inductor.  The only advantage to the usual tapped circuit is there is often a coupling link that attempts to offer isolation from common mode problems.

Pat yourself on the back, you were correct in your thinking.

Let's see,

Yes, you can use a battery

Pay attention to the voltage level.  Monitor it with a voltmeter.

Use good wiring techniques.

Charge it properly.

Inside the house be careful with wet cells.  Sulfuric acid is bad for carpets and radios.  Charging wet cells in your house can be a nasty corrosion invitation.  I would use a sealed type inside.

Fix your power supply.

Have fun.  HNY

If you don't use OCF and end fed antennas you wouldn't be looking for RF grounds.  A balanced antenna with balanced feed, proper BALUNS etc would do wonders.

As to why he thinks he needs a bunch of ground rods and heavy wires -- he reads eham posts and old ARRL books, they are full of the grounding mythology.

third prong of plug is for safety.  If its not working in your house, fix it.  Connect chassis to it for safety if the equipment has two wire plug.

Ground rods and bus bars are for lightning.  Put all that stuff outside where you want the lightning to go to ground.  Don't invite it into the shack.