John,

If you use the commercial ladder I would slit the wood and push the ladder line thru the slit.  However, the slit should be a large slit with insulating material that would prevent the wood from burning.

I prefer using brass rod with the ends threaded going thru G10/FR4 plastic.  The o.d. of the brass matches as closely at possible the diameter of the wire.

Home brew ladder line is much better than commercial.

Ideally the length of the feed line added to one half of your antenna length will be a multiple 1/4 wavelengths at the operating frequency.  Because these antennas are multi band you will need to calculate each band for the average speed spot length of your antenna + feed line length.   

Chuck

W5DXP,

Your system sound slick!  Can you share the components, schematic and physical layout?

Do you also think it is possible to measure the phase of voltage?  It seems I read somewhere
that the voltage should be 180 out of phase. 

It would be nice to flip a switch between current and voltage phase measurements.  And, It would be nice to have
BNC output connectors for a scope.

Chuck

Hi to all,

What is an excellent circuit and mechanically sound method to measure current and/or voltage and phase of current and/or voltage on open wire feeders (ladder line)?

I would also like to have two output BNC connectors for a dual trace scope.

I would also like to have two output light bulb connectors, incandescent and neon bulbs.

Chuck

Don, N3QE and all,

Thank you for your inputs. N3QE I look forward to seeing your material.

I am not sure about the voltage breakdown vs spacing gap for air single layer wound coils.

I am talking about link antenna coil types.  Some say the voltage changes along the length of
the coil.  I don't know.

Chuck

Hi to all,

I read the optimum turn-to turn spacing for a coil is about the diameter of the wire.

What about flat wire that is wound broadside to the coil form?

Thank you,

Chuck

Hi to all,

Is there any documentation, recommendations or rules of thumb that can advise me how much air gap (spacing) is needed between coil turns to help prevent high voltage arcing/breakdown between adjacent coil turns for a given voltage, i.e. 1000 volts, 2500 volts, 5000 volts, 7500 volts etc.?

I read about air gap spacing recommendations to help prevent high voltage breakdown/arcing between air variable capacitor rotor and stator plates. 

Are there similar recommendations for the output tank coil for the link antenna coupler? 

Thank you,

Chuck

Thank you to all for your input on silver plating.

Chuck

KA4POL,

Hi KA4POL,

I did a conversion of .4um and it came to 1.575 inches.

Did you mean .001575 inches thick?  Is there a reference for
silver plating these coils?

Thank you for your help.

Chuck

Hi to all,

How thick is the silver plating for "typical" ham radio HF amplifier coils?

Thank you,

Chuck

Chuck,

K0ZN has the great advice.  Get yourself a RSGB hand book or an ARRL antenna handbook.  The older ARRL antenna books from the sixties are invaluable books. 

Others above have given good advice. To sumerize a simple, efficient and capable antenna for all the high frequency ham bands would be the center fed doublet using
open wire feeders.

This "antenna system" incorporates a home brew link antenna coupler, ladder line (home brew ladder line is the best) and a random length dipole.  Some  say the minumum
length for this antenna should be no shorter than 1.25  x  the lowest band to use in meters.  i.e. if 80 meters is the lowest band that will be used then 1.25 x 80 = 100 feet.
100 feet is a "recommended" minimum length for 80-10 meters.  A zillion other lengths could be used because this "system" can be tuned. 

73,
Chuck - AA5WG

Thank you to all for your inputs.

Chuck

Hi to all,

If two coax cables were tie wrapped together to form a balanced transmission line what would be the correct method to calculate this balanced line impedance, i.e. two 50 ohm cables tied together? 

Should both ends of this balanced system have their ground/shields tied together?

Or, should just one end have their ground/shield tied together?

Would spacing the two cables further apart have and effect on the lines impedance?

Thank you,

Chuck 

Thank you for all the help.

Chuck

Can we use these numbers as a starting point/example?

28.000 MHz = 113.6821 pico farads (pf)

28.250 MHz = 112.67607 pf

28.500 MHz = 111.68768 pf

28.750 MHz = 110.71648 pf

29.000 MHz = 109.76203 pf

29.250 MHz = 108.82389 pf

29.500 MHz = 107.90166 pf

29.750 MHz = 106.99492 pf (out of band)

As a starting point how can we arrive at a straight line frequency flat plate shape (flat in the horizontal plane or plate laid flat on top of the work bench) from these numbers?

When the above numbers are plotted they show a direct curve.  The plotted curve looks like a near perfect 45/90/45 degree triangle.

Chuck

Hi Peter, G3RZP:

The shape of a rotating straight line frequency plate is similar to a cam shape.  Do you think a cam shape is going to work for this example, a flat sliding plate variable capacitor?

Would a triangle shape be better?

Chuck