Gunter (Lindy) Lindermeier, WW5AA

So you need that first HF antenna

I have been reading many posts here lately from new amateurs and some not so new about installing that first HF antenna. It appears that many are mislead by commercial advertising or a mish-mash of partial information. In my case, I can't see why anyone would spend $279.99 for an off center fed dipole or even $79.95 for an imitation G5RV and then hang the thing at 25/30 feet. It is not my intent to write an antenna handbook or to tell anyone that the described doublet antenna is the best thing since sliced bread. My intension is to go step by step in building an antenna that will work very well, at least as well as any commercial wire antenna while costing a fraction of the price. One that is simple enough in construction that even a caveman can do it using parts that most folks have around the house or can be obtained at any hardware store.

One of the important parts of constructing any antenna is getting it in the air. A lot of folks are disappointed when that new wiz-bang antenna hanging at 25 feet just does not cut it. Altitude is an easy task for those with tall towers or even some very tall trees, but…..what if the budget will not allow for that tower or no tall trees within reach? How about if you're like me, getting a little long in the tooth and not fond of climbing 60' or so into that tree? In my case, a mast is the logical choice. Here again I see people limiting themselves by trying to Armstrong a tall spindly mast into the air. For many, this is the road to disappointment and bent aluminum or splintered fiberglass.

I use my home brew mast launcher, based on a design which has been in use by the military since WW-I. Again, low cost and readily available parts and ease of construction are the selling points. The mast launcher also reduces the problems associated with raising the doublet ends to a usable height. Many do not realize that an all band doublet becomes less efficient as the angle of the elements from horizontal increases past 30 degrees.

Since I like using the military heavy duty mast sections I have designed mine for that use. My primary goal was getting safely as high as possible without any help. Also since the masts are an integral part of the system, I constructed a center connector that would attach easily to the mast, yet be fairly robust. One could use a pulley and rope to raise the center but since it is very easy to raise and lower I prefer my method.

I am by no means a mechanic or carpenter and most of you can probably build a better launcher. The basic concept is something to support the mast while it is being raised. Since I test antennas all the time I needed a way to get a wire up at least 50' without help. I have two masts mounted on rails of the rear porch so that I can do A-B tests on all the great antenna designs I hear about.

The basic concept is a three sided 2X4 (rear is cut to fit) box just wide enough and long enough that it will allow the mast section to be inserted into the PVC pipe. Mast sections are then simply fed in one after the next.

After loading the first two mast sections it is only a matter of attaching the center connector of the doublet. I use a properly sized section of PVC which fits the stub end of the mast section.

As shown below, two slots are cut into the PVC along with two holes for the lead from the 450 Ohm ladder line to the elements. The ladder line is then pushed through the slots. I trim about 6” leads at the end of the ladder line.

The leads are fed through the holes as are six inch sections of 12 ga. Wire to strengthen the attachment point for the elements.

Notice the Gerber baby food jar top….when I said cheap I meant it! The PVC section is then pushed onto the mast stub.

The openings in the center connector are then sealed with silicon and painted. I like to use Krylon plastic paint. The ribbing at the mast joint allows condensation to escape. A couple of coats of paint and even Lynne, the XYL says it looks good. With the elements and guys in place, the connections are soldered and it's time to start stacking mast sections.

The doublet elements act as guy wires at the top, while Dacron rope is used four feet down in the opposing direction, then again four feet down another set of opposing Dacron guys. While the mast is going up, I use bungee cords at the ends of the elements and guys. This allows for tension one mast section at a time. I like to use a pipe clamp at the base of each mast section for added strength and as a good attachment point for the guys. Again I designed this method so that I could complete the set up alone. One of my original masts with optional humming bird feeder is on the right. On this mast the top elements are 88.5 feet each side and the second set of guys are elements cut for 60 meters. I found that in A-B tests, the coax fed resonant 60 meter antenna was usually no better than the doublet. The new antenna is 126 feet per side so that the lower end of 160 meters could be reached with the auto-tuner. Since I have a small city lot, my doublet is bent into a straightened out “Z” shape (bends at less than 90 degrees). This arrangement is much more efficient than coils or traps. With proper planning you may be surprised at how much wire you can put up on that small lot. Just remember that you can hang as much wire as you can, than make small adjustments at the lowest frequency that your tuner will handle.

Ok, up at 60 feet and time to see what it looks like on the AEA analyzer on loan from Ronnie, W5REH. During the raising process I use my MFJ-259B to make spot checks and possibly avoid having to start at square one if there is a problem.

I use receiving antennas (coaxial random, and wire loop) rather than transmit and receive on the same antenna. I will not go into all the reasons why (I'll save this for another time). The big question now is how good does this cheap antenna work? I do not believe in listing the DX stations that I have worked with it on 160 and 80 meters, even while using it for receive, since this is not how to evaluate the effectiveness of an antenna. But let me say that if you are using that G5RV, folded dipole, mystery antenna, lazy “H” or any of the arrays at 30 feet, this antenna at 60 feet will make you smile

I would encourage anyone that is interested in building this doublet to sign up at the new site below. I would like to thank the folks at antenneX for continuing this wonderful web site!

http://www.cebik.com/radio.html

COST:

1. 252 feet #12 wire…………….. $37.80

2. 2X4 and PVC pipe……………. $ 7.97

3. 250 feet inch Dacron line…...$24.87

4. 4 foot mast sections (80')….…. $97.00

5. Paint/screws/misc……………..$12.00

TOTAL: $179.64

73 de Lindy