COBWEBB ANTENNA PDF
COBWEB,HF,1/2W,8-BD,6,10,12,15,17,20,30,40M,KW . MFJ Cobweb Antenna turns your space problem into a stack of QSL cards from far away places . Ideal HF Antenna. Efficient. Transmitter power gets converted to RF, not to heating the ground, coax, or matching network components. G3TPW CobWebb Antenna for the 14, 18, 21, 24 and 28 MHz Bands All the other small multi-band commercial antennas that are available are less than.
|Published (Last):||7 July 2015|
|PDF File Size:||19.89 Mb|
|ePub File Size:||17.38 Mb|
|Price:||Free* [*Free Regsitration Required]|
You simply wind a total of 8-turns: The frequency of the SWR minimum can be tuned by changing the length of the dipoles.
CobWeb Aerial | M∅PZT
See all condition definitions – opens in a new window or tab Representative APR variable Mouse over to zoom – Click to enlarge. Skip to main content. See the seller’s listing for full details. Learn more – opens in a new window or tab. The mounting arrangement consists of 2 plates — The 1st holding the main crossover poles 1 on top, 1 underneath and the boom, the 2nd supporting the boom and fixing to a mast.
The item you’ve selected wasn’t added to your basket. cobwfbb
The Cobweb antenna is a antenna which is easy and fast to install for portable operations, designed by G3TPW. Please allow additional time if international delivery is subject to customs processing.
Balun Construction There are 2 ways to make a CobWeb antenna: Estimated delivery dates – opens in a new window or tab include ccobwebb dispatch time, and will depend on postal service selected. Due to the arrangement of the antenna elements and some ground effect the gain is slightly higher than for a dipole alone. There are 2 items available.
Accepted, Eligibility for PayPal Credit is determined at checkout. This raises the feedpoint impedance by a factor of 4 and provides a good match to 50 ohm feedline; the feedline is usually coiled to form an air-cored common-mode choke close to the feedpoint.
Email to friends Share on Facebook – opens in a new window or tab Share on Twitter – opens in a new window or tab Share on Pinterest – opens in a new window or tab. Click on the photos on the right for enlarged pictures, and see the bottom of this page for more construction details.
The Antenna is in size 2. The 10m wire is therefore around 40mm from the ali-tube and the 20m wire is only 20mm from the edges of each spreader. Although not strictly necessary, I find it helps keep things neat if you slide a few narrow pieces of heat-shrink tubing over the coaxes to keep them together.
Here are clbwebb final readings from the MFJ — Not bad!
The base plate as well as the tube supporting the balun is made from aluminium, the tubes carrying the dipoles are made from glass fibre. Good bit of kit.
The wires are terminated in solder tags which fit over 4mm bolts screwed through the terminal box. The CobWeb has no lossy components in it, so there are no power limit problems for the. Customer specific antennas telescope antennas etc. Full IP67 with Scotchcast 40 inside the feedbox. People who viewed this item also viewed. Report item – opens in a new window or tab. Contact the seller – opens in a cobwegb window or tab and request a postage method cibwebb your location.
A Stormy New Year Celebration: Seller assumes all responsibility for this listing.
When cobwsbb with a Please enter up to 7 characters for the postcode. Watch list is full. Equally the wind surface is rather small, allowing a max.
High Quality 5 bander CobWeb Antenna
The ends of the dipole elements are connected to spacer cords approx 6″ long using the brass inserts from plastic connector blocks; this arrangement allows any slack to be taken up easily by releasing the srews and sliding the wires through the inserts.
Now wind 8 turns of this twin cable onto a FT toroid to form a 1: These small sizes and the small packing size of 11 x 11 x cm makes this antenna well suitable for vacations, fielddays, SOTA and other portable activities. The height whilst on-test was 10ft, about 4ft under my dipole and the comparison test was quite favourable.
Instead of using tie wraps to keeps the wires in place we use a UV resistent Zig-Zag Connector allready mounted on the spreaders, just fold the antenna wire between the connectors. Computer modelling of this arrangement shows that one result of bending the dipoles is that the antenna is close to being omnidirectional in azimuth, with a Free Space eccentricity of about 4dB; a less attractive result is that the feedpoint impedance drops to around 12 ohms at resonance.