Thursday, Feb 26, 2004 at 11:43
I carry a long length of Figure 8 wire.
I broke the stainless steel whip and just connected a piece of insulated wire to top of auto tune It was about 2.2 m long. tied this off to poat andit worked a treat.
Here is an extract on emergency aerials
There may be occasions when damage to a whip antenna, distance, or topography
makes communications difficult or non-existent. In such cases a wire antenna
can be constructed which will, in most cases re-establish communications.
The length of the antenna has a direct relation to the frequency of operation
therefore the wire must be cut to the correct length. The following formula
will give the length of an emergency wire antenna.
Length in metres = 71.25/Frequency (in MHz)
e.g. 71.25/3.995 MHz (3995kHz) = 17.84 metres.
Length in feet = 234/Frequency (in MHz)
e.g. 234/3.995MHz (3995kHz) = 58.57 feet.
The length of wire required for VKS - 737 frequencies is as follows:
Frequency Metres Feet
3995kHz 17.84 58.57
5455kHz 13.06 42.90
8022kHz 8.88 29.17
11612kHz 6.14 20.15
14977kHz 4.76 15.62
If insulators are used, the length is measured from the hole in the insulator
through which the antenna wire goes. Therefore, the wire must be cut longer
than the calculated length to allow for insulator wrap around.
Obtain some copper wire (preferably plastic coated) and cut it longer than
the length calculated for the frequency. Attach an insulator
(nylon rope will do) to one end of the wire so that the distance between the
hole and the end of the wire is the correct length.
Attach a length of rope and a weight to the end of the rope with the insulator
on, throw it over a tree and pull tight.
Strip about three centimetres (one inch) of the plastic coating off the free
end. Poke the exposed wire between the coils on the antenna spring base,
REMOVE THE WHIP ANTENNA.
In general the most effective wire is approximately 45 degrees to the ground
and broadside to the base station. When there is no means of hoisting the
wire up, it can be laid out in a straight line on the ground. In this
case propagation occurs with maximum radiation in the direction in which
the free end points.
AnswerID:
48188
Follow Up By: Member -Bob & Lex (Sydney) - Thursday, Feb 26, 2004 at 12:59
Thursday, Feb 26, 2004 at 12:59
What size copper wire? Will household power cable do?Regards Bob
Where to next
FollowupID:
310088
Follow Up By: Peter - Thursday, Feb 26, 2004 at 16:13
Thursday, Feb 26, 2004 at 16:13
basically any insulated wire will do.
By household power do you mean single core or multi strand flex.
I would use multi strand flex.
Or down to dick smith /jaycar and get a multi strand cable with diameter of 1mm or bigger. It is cheap
What we are talking about is radiating the signal from a wire.
The length is the most important thing so there are no reflection back to transmitter. VSWR is the tecko name.
You can pole the stripped wire into the centre of coax on extension of 910 aerial. Just ensure that it does not touch the body of car radio / anything.
You will then need to set your radio to a manual or whip type aerial for it to function.
I have to do this with my barrett 550
FollowupID:
310112