7 band 1 Kw cobweb

---

COBWEB ANTENNA 1 Kw  7 BAND HF TWIN WIRE  CUSTOM BUILT 4-6-10-12-15-17-20

BUILT IN THE UK BY RADIO HAMS FOR RADIO HAMS

NOW AVAILABLE IN 5 OR 7 BAND VERSIONS

please wear gloves when working with fiberglass

total weight 7 kg
 

This is not a kit it’s a complete antenna that covers 14-18-21-24-28-50 MEG and proving to work very well on 70 meg 4 meters

NOW WITH HEAVY DUTY CABLE MOUNTING P-CLIPS
OVER ALL SIZE 8'6" SQUARE (2.59 METERS )
MOUNTS TO A 1 1/2 to  2" POLE
WIND SPEED  WILL TAKE 120 MPH PLUS
 

This cobweb was custom built by me following the cobwebb reveled instructions
The modifications I made were the supports there are now fewer parts and less joints.

I USE 16MM SOLID ROD NOT 12MM AS THE ORIGINAL HAD
I use protruded fiberglass rods an tubes for extra strength.
All the other parts are as the instructions.PLEASE WEAR GLOVES WHEN BUILDING ANTENNA

But I used twin 42 strand figure 8 cable unlike the 16 strand that was used so the antenna will now take more power.
I use the same junction box that is sealed inside and outside .

We use very tough alloy plate6.35mm thick for the cross support and mast mount all u-bolts are galvanized so they

will not rot away and are fitted with nylock nuts so they will not come loose and fits to a 2 inch mast.
THE JUNCTION BOX HAS S0239 SOCKET FITTED SO A STANDARD PL259 PLUG WILL FIT IN
 So all you need is to feed it with a run of any 50 ohm coax of any length.

24 Top quality cable ties will be sent to secure the element to the rods as in the pictures.
This antenna has been set on a 6 foot alloy pole a little

tuning will be required for full band coverage an atu maybe needed on some bands.

You may need a few small cable ties for fine tuning the elements.

but full instructions on how to tune the antenna along with the construction instruction

will be posted and taped to the antenna when it arrives.

PLEASE NOTE AN ATU MAY BE REQUIRED FOR SOME BANDS
The overall size is 8 foot 6 inch square.
All the elements double gama t matches are sealed with high quality heat shrink to keep the weather out.
The cobweb is fully Omnidirectional so no need for expensive rotators.

A dipole or a CobWeb has a gain of about 5dB over a dipole in free space,

(due to ground reflection) or 7dB over an isotropic radiator (7dBi) and will work equally well over the entire band

.The CobWeb has no lossy components in it, so there are no power limit problems for the 

QRO operators 1000 WATTS PLUS.1Kw  ssb

500 watt ft8 and digi modes

.The low loss and consequent high radiation efficiency 95% also makes it ideal for QRP!

we recommend you add a 6 turn coax choke on a 100mm tube but may not be needed
 

 Pure horizontal polarization so very little chance of EMC or static problems.
You will get 6 half wave dipoles one each side with no nulls or flat spots in a space of

less than 9 feet square.You even get 2 heavy duty pole clamp u-bolts to fix to your 2 inch scaffolding tube with nylock nuts.

NOW WITH SINGLE PIECE BOOMS AT 1.44 METERS  AND 2  REINFORCED TUBES IN THE CENTER HUB
This was done as a radio club project so some of the best brains in ham radio went into building this.

An ATU may be needed due to the spread of the bands covered by this antenna as with any dipole.