I've had many requests for a ready-made J-pole design that will enable the
Packet Radio user to print the image from a web page and go directly to the
construction table and build a J-Pole antenna for their Packet Radio station.

The object is to eliminate the need to go through all the calculations on
another page of this website.  These requests are valid and understood!
With your requests in mind, here are "the real world" designs that I've
personally constructed and use at many of my Packet Radio node locations.

To make a hardcopy of this web page, go to the small "printer" icon of
your NetScape (or IE) browser and CLICK on the icon.  This will enable you
to print this text and the two attached illustrations for future use.

A VARIATION ON A THEME:

Let's look first at FIGURE 1a;  This is the overview and profile of the
J-Pole we will be working with.  There are two different bands we will be
building the J-Pole antennas for.  NO, we will not build a two band antenna
on one mast.  I've been there, done that.. and it is an excercise in futility.

For openers, I would like to show you that all J-poles are not created equal.
By that statement I mean, we will modify our construction techniques a bit
and apply a variation to the theme.

Notice in the exploded view at FIGURE 1b, I've deviated from the usual RF feed
technique that we normally use to attach our coaxial cable to the J-pole.

Where we usually attach the shield and center conductor to the tuning stub and
the driven element with aeroseal (hose) clamps, here we've made a slight change
in the design by exchanging the elbow for a tee.  Below the short (1/4 wave
tuning stub) section, we (carefully) soldered an SO-239 (Chassi-mount) coax
(female) connector.

But notice that we must first attach a piece of number 10 or 12 insulated,
copper wire to the SO-239.  The length of this wire depends on the spacing
between the stub and (Fig 1A "D") long section of our antenna.  

If the antenna is for six meters, the wire length will need to be about, 10 to
12 inches long.  If our antenna is for two meters, the wire length will be less
than 8 inches overall.

I am careful when I (Benz-O-Matic torch) solder the SO-239 to the copper tee,
since I don't want to heat the SO-239 to the point the solder on the wire melts
and I have to start the process over again.

For 2 meters (145.000 to 146.000 MHz) the EXACT dimensions are:

	A =  58 inches overall (Long, driven element).
	B =  19.5 Inches
	C =  2 Inches
	D =  1.8 Inches (space)
	

For 6 meters (50.500 to 51.500 MHz) the EXACT dimensions are:

	A =  166-3/4 inches overall (long, driven element).
	B =  58-3/4 inches (short, tuning stub).
	C =  5.5 Inches
	D =  5 inches

FIGURE 1a

FIGURE 1b

E-mail BucK4ABT

Stainless eyebolt is inserted into Tenyte "Center Insulator"  The "Center Insulator" is used to suspend the center of a Dipole,  Windom, or other wire type antenna from tower, tree, or support structure.	Center Insulator with Suspension Eyebolt	1.99  Order CIA    Center Insulator and two end insulators  3.99  Order CIAX3
For the apartment dweller, you can now hang the 20 meter doublet in the attic.  I've QSO'd with stations all over the world with the 33 ft dipole in the attic of my garage.   One insulator at the center, and one each end.   It's great for other HF WINDOM and or dipole antenna.  Dielectric strength is better than the old ceramic insulators, but without susceptibility to cracking or breakage under impact or extreme temperature changes.	ANTENNA  INSULATORS	Package of  3,  $2.99   ANTINSL3   Package of 10,  Insulators $8.99, ANTINSLX10
Dipole and inverted-Vee antennas are commonly "balanced" at the feed points.  Coaxial feed lines are "unbalanced" by design personality (thus the name BALUN).  This BALANCED, to UNBALANCE marriage can only be performed by using a BALUN.  A BALUN should always be used when feeding wire antennas with coax to make certain characteristic antenna performance and optimum transfer of RF energy to the antenna complete. When coax is used to feed antennas without the benefit of a BALUN, current flows on the shield of the coaxial feed line .  This coaxial shield current can produce  a "Hot HAM shack,"  This can result in nasty R.F. injury from the microphone to lips, hand key to fingers, etc., and is often more pronounced at certain frequencies.  Coax cable shield currents can also cause damage to your HAM gear.   TVI, RFI, telephone and even wild VSWR indications can result from these shield currents.   In 85% of antenna projects that displayed these problems, when a BALUN is added to the coaxial line or near the antenna feed point, these problems were diminished or completely eliminated.
At BUX COMM, *We don't cut corners!  The components used in the manufacture of our BALUNs are from top quality components, beginning with the Silver Plate SO239 connectors and center insulator is made of teflon™(E.I Dupont). The wire we wind the ferrite donut with, is heavy-duty, silver flashed wire, with teflon™ insulation, which will handle RF voltages above 5000 volts, and temperatures above 2000 degrees. The binding posts are heavy-duty, tempered brass, with end holes and side-thru holes to accommodate either type loop-thru connection. A double-shoulder brass capture nut is used to add a secure bite and improve electrical connections to the wire .	4:1  1.5 Kw Balun,  BUX BALUN 41HD     Toroid  design, wound with teflon covered, silver plated wire.* Heavy-Duty, construction. o 50 ohm, SO-239 unbalanced input o Heavy duty Hardened Brass, Balanced output connectors o 1.8 to 50 MHz o Toroid (Voltage) design o Heavy Duty, Lightweight construction o Sealed against moisture SPECIAL This Month... !!  BONUS SALE ! Buy either our 4:1 HD  or our 1:1 HD ↓ BALUN and receive "FREE," a Package of three Insulators, as shown above.	41HD $19.95
1:1, 1.5kw Balun, BUX BALUN 11HD $19.95 o 50 ohm, SO-239 unbalanced input o Balanced output o 1.8 to 50 MHz o Toroid (Current) design o Heavy Duty, Lightweight construction o Sealed against moisture	1:1, 1.5kw Balun,  BUX BALUN 11HD  Toroid design, wound with teflon covered, silver plated wire.* Heavy-Duty, construction.	11HD  $19.95
BUX BALUNs   should be installed at the antenna feed point, or where the coax or feed-line attaches to the above ground antenna.  BUX BALUNs are used to connect balanced antennas to unbalanced transmission lines, such as coax cable.  Their primary purpose is to prevent antenna (RF) currents from flowing down the outside of the cable.  Another function of the BUX BALUN41 is to match the impedance of an unbalanced coax to the balanced feed point of a balanced input antenna(s). BUX BALUNS may also be used as “line isolators” anywhere along the cable to prevent the destructive influence of induced RF currents (VSWR). BUX 1:1 BALUNs are current BALUNs. They consist of several large, number 73, ferrite type 44 cores.  BUX BALUN11 operate from 160 to 10mtr MHz and allow use of RF power to the rated capacity of the BALUN.   BUX 4:1 BALUNs are voltage BALUNs. They consist of a large, number 43, ferrite dough-nut bobbin.  BUX BALUN41 operate from 1.8 to 30 MHz MHz and allow use of RF power to the rated capacity of the BALUN. 4:1 High Performance, Heavy Duty, *2 KW Balun (if SWR is less than 2:1)   *CW/SSB duty-cycles only.     SSB/CW Power @ 3.5 MHz* >1.5 kW if SWR is less than 3:1  *Not rated for AM, RTTY or other high duty-cycle digital modes. Double-co-efficient coupled design. Exceptional High output. Large toroid ferrite cores. High winding reactance with only a L-C compensation. Teflon insulated, large gauge, high temperature, wire. Compensation for wide bandwidth Rated above the legal power limit. Stainless-steel eyebolts. Input Connector SO-239 Output Connector Hard-Drawn, tempered Brass Binding Posts. Bandwidth 160 - >10 m. Power Loss, dB less than 1 dB.
BUX ONION $19.95 "Decoupling Transformer" BUX UN UN De-Coupling transformer, has SO-239 (female)input connector and output connector is 1 ft Mini 8 cable with PL-259 (male). BUX ONION is an UNbalanced to UNbalance (UN-UN) decoupling transformer designed to be used by the Apartment dweller or the RV ops.  It is also used with the DBLSPCL antenna.   High RF currents traveling along the coax feed-line shield can cause high VSWR.  This decoupling transformer prevents RF currents from traveling down the outer shield of the coax. The input connector is an SO239 (female) and the output connector is a PL259 (male).	BUX ONION  $19.95	BUX ONION  $19.95
Important Information;                                    WHY USE A  4:1 BALUN Krusty Olde Kurt is now going to repeat himself.  Why? Because the same question keeps coming up over and over. And he wants everyone to get it right.   "I'm feeding my dipole with 600-ohm line.  At the station end I need a balun to convert to 50-ohm coax. I need a 12:1 balun, right?"   Wrong!  A 4:1 balun would be better.  Why is that?  If your dipole is up, let's say, 35 feet then on 80 meters it will probably have a resistance at resonance of about 40 ohms. The actual resistance depends on the height above ground in wavelengths.  If the dipole is 40 Ohms then what do you see at the transmitter end of your 600 ohm line? If the line is a half-wave long (120 ft on 80 Meters) you'll see 40 ohms.   Remember, a half-wave line repeats what it sees at the other end.  But if it is a quarter-wave long you'll see 8500 Ohms!  At other line lengths you'll see impedances somewhere between these two extremes.   So you are not going to see 600 ohms at the end of your 600-ohm line. That only happens if you have a 600-ohm antenna hooked onto it. With such a variation in impedance at the trans­mitter end of the line there is no one balun transformer that will match it. Most of the time the impedance will be above the 50 Ohms of your coax so a high impedance balun would be desirable.  Unfortunately high imped­ance baluns don't work well when not matched.    Experience has shown that 4:1 baluns work best in this service.  They are more rugged and will take bad mismatches especially if they are wound on an iron powder core.  So stop searching for that 12:1 balun. Use a 4:l BALUN and your system will work great.   You can read Kurt N. Sterba “AERIALS” column in World Radio Magazine.