Details 2-El.-2m 3-El.-2m 4-El.-2m 5-El.-2m new 6-El.-2m 7-El.-2m 7-El.-70cm 9-El.-70cm 10-El.-70cm 12-El.-70cm 14-El.-70cm
 Stacked 5-El-2m 25-Ohm new 7-El.-2m  25+ 28-Ohm  new 8-El.-2m  28-Ohm 10-El.-70cm  28-Ohm

Cheap and simple VHF-/UHF-Yagis by DK7ZB, extreme lightweight for portable use

 The dimensions given for the Yagis in this chapter are for non-conductive booms like PVC. If the elements are mounted through or very close to a conductive boom, you need a proportional correction factor depending on the distance of the element to the boom. This assembly will cause an electrical “shortening” of the element, that means it is shorter. This must be corrected through a corresponding extension of the element. Günter Hoch, DL6WU, has found the correction factor for mounting through a conductive boom by a complex series of experimental measurements with the following formula: BC = 100%-factor (in wavelengths), BD = Boom diameter in wavelengths However, this factor is somewhat inaccurate and it is only an approximate value because it depends on the reactance of the respective element. The shorter directors have an increasing capacitive reactance and would correctly require a different correction value. To avoid these problems completely, you should assemble the elements so that no correction is necessary. The table gives the 100%-factor for 144 MHz, for 70 cm double the values. Other mountings see the picture below.
 What you can do with these leightweight constructions you see on the picture. Bob, ZL1RS with  4x5-El.-1,50m-50-Ohm-Yagis as A35RS on Tonga   Link to his page with a lot of informations about his expeditions: ZL1RS
 My "shack" for portable operation. I use the 2x6-El.-50Ohm-Yagi for 2m with 2,50m boom an 2x10-El.-28Ohm-Yagi for 70cm with 2m boom.  The mast has a height of 8m and can be erected easily without any helpers. A 400W-AC-generator or 2x100Ah lead acid batteries gives the power for several hours of operation. I like short regional contests on VHF/UHF.
 These Yagis are constructed with cheap leightweight materials for electric installations and you can mount and dismantle them without any tools. The boom is made of PVC-tubes with 16mm, 20mm or 25mm diameter, the element holders are the clamps for these tubes.  A little bit more weight, but more stable construction is possible with 16x1mm and 20x1,5mm aluminium tubes as a boom. If you build up the leightweight 28-Ohm-Yagis, you must ground the coax socket to the boom. For the construction look to the "DK7ZB-Match". The elements are made of Aluminium-welding-rods (material AlMg3) with diameters of 4mm, 3,2mm or 2,4mm. Normally this rods are sold in packages with 1kg (Price in Germany 8-12 Euro/kg). You can use 6x1mm tubes, if these rods are not available for you.
 Diameter Weight/piece 1m Pieces/1kg The different elements 6x1mm 42g 23 4mm 34g 29 3,2mm 21g 47 2,4mm 16g 62
 As a mast you can use a telescopic fishing rod or thin Aluminium-tubes for tents. Pse look for all pictures with the mechanical details, may be you find your own solution with parts available in your country!
 The 6-Ele.-Leightweight-PVC-Yagi of Paul, G3YDY G8BVG/p in JO01HP    Winner of the British Backpackers Championship 2008      In this QRP-contest max. 10Wtts are allowed, ODX 718km with DL0GTH

Details from Paul (G3YDY) of his Yagi-construction. Click on the thumbnails!

 4x6-El.-Lightweight-Yagis during the BCC-Meteorscatter-Contest in the Geminids 2008 in a rare square. One man operation with car, tent and 0°... Dirk,  EI/ON5GS/p in IO55XC   For more pictures click the LINK

 OE/OL1D with the 7-El.-2m-Yagi   in the Alpe-Adria-Contest 2009 Heukuppe - Rexalpe  2007 m ASL

 All is possible with these lightweight constructions: The portable satellite Yagi ("arrow-style") for 2m and 70cm, built by Adamos,  SV2KGA
 Lightweight-Yagis for 2m and 70cm built by  Jos,  PA3ALF   Details on his page: Link to PA3ALF

Max. mounting lengths of the PVC-tubes for the boom:

 Diameter Without additional support With Kevlar rope above the boom 16mm max. 1,00m max. 1,50m 20mm max. 1,50m max. 2,00m 25mm max. 2,00m max. 3,00m

Max. mounting lengths for the boom with aluminium-tubes:

 Diameter Without additional support With Kevlar rope above the boom 16mm x 1mm max. 2,50m max. 4,00m 20mm x 1,5mm max. 4,00m max. 6,00m

The parts for a 4-El.-Yagi with 1m Boom

The 2m long 6-Ele.-Yagi has a boom of two pieces, therefore no part is longer than 1m

 The most Yagis have an impedance of 50Ohms and are fed with a lambda/4-choke for 2m and a 3/4-lambda-choke for 70cm. You can use the same chokes for 2m and 70cm! The length of the coax-cable should be about 40cm (not critical!). The radiator is a stretched dipole with 10-12mm insulation between the two parts. The insulated part is a piece of glass-fibre (from a broken tent of my children!). Commercial Polyamid-parts (left) available at  www.nuxcom.de. For the 28-Ohm-types with aluminium boom use the DK7ZB-match with a grounded coax-socket to the boom The given length in the tables are from tip to tip. The Yagis are optimized for 144,3MHz to use them for SSB/CW.
 The radiator box with RG-188-PTFE-coax (for 2m and 70cm), 250Wtts on 144MHz and 100Wtts on 432MHz Another box for 2m with RG-174, 100Wtts on 144MHz

The choke with ca. 40cm RG-58/MIL (use good quality!) handles 200W SSB/CW on 144MHz

The middle part of the 4-El.-2m-Yagi with the boom clamp

This picture shows the boom from the side

 These pictures show the genious construction of the radiator-box for a dismantable Yagi with 4mm-rods. The photos are better than a lot of words. Construction by Rolf, DH6RM
 Mounting of the elements Drill a hole (3,9mm for 4mm-elements or 3,1mm for 3,2mm-elements) and push the elements through the holes. Ready! If the elements are not fixed enough on the boom, put two windings of PVC-tape around the boom and clip the clamps then on the boom.
 A little bit more difficult is the reflector, because it is longer than 1m, the welding rods have exactly 1m length. Make two pieces of 50cm length and take an aluminium tube 6x1mm. Then you can drive in the 4mm-rods with a hammer.

 The reflector with 3,2mm-rods, the middle part is a brass tube of 4mm. Here I used a 16x1mm-aluminium-boom. To avoid corrosion problems between Al und Cu the middle part should be coated with a colourless paint. Keep in mind that these antennas are only intended for portable use!

 The easiest way to fix the element is to drill two holes into the clamp and fix it with a cable tie. Use black ones for the UV-stability-

 Another simple mounting method for the elements, here with 2,4mm-rods With this elements and two fishing-rods mounted back to back a long boom for portable operation is possible

 The bracket for the mast-boom-connection for the longer booms is made with a piece of aluminium and four clamps:
 These are mounting parts used by Alfred, PA7AL
 The mast to boom connection by PA7AL
 Mounting with Heyco-snap-in-bushings (available at NUXCOM) for 15x15- or 20x20-mm-square aluminium booms The example below shows 4-mm-aluminium-welding rods through 3,2-mm-bushings. When using this method with mounting through a conducting boom (round or square) add the following lengths to each element (reflector and directors): 15-mm Boom: 1,5 mm for 144 MHz, 3 mm for 432 MHz 20-mm-Boom: 2,5 mm for 144 MHz, 5 mm for 432 MHz