pi coil

pi coil

Antennas : 40M

• Homebrew 20/40m Travel Antenna - This is a low cost homebrew two band travel antenna for 20 and 40 meters. It is based on the B&W Travel Antenna concept with a telescoping whip and a loading coil
  [ Hits: 17493 | Votes: 15 | Rating: 5.86 ]

• 40m loaded dipole - This is an short dipole for 7 MHz. Total length of this dipole is just 10 meters, 33 feet. Missing lenght is balanced by a coil made of 49 turns of a 40mm diameter pvc pipe. The use of a choke balun is recommended, as always, to adapt the unbalanced coax cable to the balanced antenna, and to prevent RF feed back along the coax shield.
  [ Hits: 194 | Votes: 4 | Rating: 8.75 ]

• Microvert Antenna for 40m by ON7IR - A mircovert antenna assembled for the 40m version of the DL7PE antenna. A one meter long aluminum tube with 24mm diameter is used for the base (element 1) and a 50cm aluminum tube with 20mm diameter for element 2 (the extention). A pvc pipe, 34cm long and with a diameter of 38mm, is used to wind the coil on (1mm enamelled copper wire).
  [ Hits: 152 | Votes: 0 | Rating: 0 ]

• Loading Coil for 136 kHz - Pictures of loading coils according to OK1FIG
  [ Hits: 1499 | Votes: 1 | Rating: 3 ]
• Make Your Own Loading Coils - Make your own loading coils for antenna projects using Caterpillar Grommet strips.
  [ Hits: 1403 | Votes: 3 | Rating: 7 ]

• Multi-band End-Fed Antenna - An excellent guide to homebrewing multi band end-fed antennas. The article, embed several drawings including diagrams and detailed pictures, illustrating the basic funcionality of end-fed antennas. The author gives some basic hints on how to build a half size antenna for 80 40 to 10 meters and a 6 meter to 40 meter configuration. It is also well described how to build the impedance transformer and the loading coils for lower bands.
  [ Hits: 1105 | Votes: 6 | Rating: 4.5 ]

• End Fed Half-Wave Antennas - An interesting article on end fed half-wave wire antennas with a couple of original experiments. Author illustrate the role of the QRP matchbox, and a 40/20 meter antenna with a center stub making it a large bandwidth antenna for 40 and 20. Includes also an 80/40 end fed with the typical coil to make it available on 80 merts band.
  [ Hits: 288 | Votes: 2 | Rating: 10 ]

• Half Wave Fan Dipole Antenna - Amateur Radio 40m 20m 15m Half Wave Fan dipole antenna project with part list, pictures and drawing. Includes the option to expand the antenna to cover the 80 meters band
  [ Hits: 681 | Votes: 1 | Rating: 1 ]

• Build your own RF-Choke - How to make an effective RF Choke. The coiled coax choke is the easiest to make but also the least effective. This article includes some general guidelines for winding coax chokes on a 10cm PVC pipe using RG-58 or RG-213 coax cable.
  [ Hits: 792 | Votes: 12 | Rating: 7.33 ]

• A $20 HF mobile antenna - A few hours of fun with PVC and wire and you have got yourself a respectable road radiator. The antenna consists of little more than some PVC pipe topped by a RadioShack replacement whip antenna and a couple of coils made from a small roll of #14 house wire.
  [ Hits: 10547 | Votes: 6 | Rating: 7.33 ]
• DIY Portable Car Whip Antenna - Being frequently away from home, the author owner of an Elecraft KX3 missed the opportunity to work /M. They devised a portable antenna solution, incorporating a coil and car body, enabling multi-band tuning. Despite its unconventional design, the antenna exhibits promising performance, resembling a vertical dipole.
  [ Hits: 54 | Votes: 0 | Rating: 0 ]

• Petlowany Antennas by K6NO - WorldRadio Article on Petlowany antennas base on this principle: if a length of wire is wound into a spiral-shaped coil and excited by a radio frequency current connected to the innermost portion of the coil, it will then, and only then, exhibit RF characteristics that closely approximate those of a resonant linear wire of the same length
  [ Hits: 3765 | Votes: 9 | Rating: 6.22 ]

• Antenna Efficiency - K0BG article con antenna efficiency covering topics like radiation resistance, coil losses and ground losses, other kind of losses. How calculate efficiency and Bandwidth Notes
  [ Hits: 458 | Votes: 0 | Rating: 0 ]

• The Squid Pole Wire Antenna Re-visited - The author explores enhancing the performance of a 7-meter fiberglass squid pole wire antenna for amateur radio. The wire, resonant at 10MHz, poses impedance challenges on various bands. Experimenting with direct coax feed and UN-UN transformers, the LDG Z11-Pro2 auto-tuner is found effective but may show deceptive SWR readings. The author employs adjustable UN-UN ratios and introduces a custom "porcupine" coil to optimize the antenna's efficiency.
  [ Hits: 91 | Votes: 0 | Rating: 0 ]

• Pierce Aluminum - Distributor of aluminum and a manufacturer of finished aluminum products. Pierce Aluminum offers a diverse inventory and distributes a complete line of sheets, coils, plates, bars, structural shapes, tubes, pipes and extrusions in the most varied alloys and sizes possible
  [ Hits: 1053 | Votes: 2 | Rating: 10 ]

• Inductor Calculator - Calculate inductance online, with the cylindrical Coil Inductor Design Equations Formulas Calculator
  [ Hits: 279 | Votes: 1 | Rating: 1 ]

• A good regenerative receiver - A good SSB-CW-AM regenerative receiver with a fine tuning by moving the wooden stick with a grounded piece of PCB towards the coil.
  [ Hits: 7258 | Votes: 9 | Rating: 8 ]

• Grip Dip Oscillator - Originally eveloped by I1FLC, uses seven plug in coils covering 3.0 to 30Mhz in a Colpitts oscillator circuit.
  [ Hits: 667 | Votes: 1 | Rating: 10 ]