I'm not sure, probably none but it's a lot better then those rubber duckies
on HT's and I know a couple people that use them on 706's that live in
apartments, and have the antenna hanging from a tree and they do about as
well as anyone.
----- Original Message -----
From: "Colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, February 15, 2005 11:18 PM
Subject: Re: Twin lead J pole
> what sort of gain is calculated for the twin lead J poll design?
> Regards
> Colin
> ----- Original Message -----
> From: "John Miller" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, February 15, 2005 4:44 PM
> Subject: Re: Twin lead J pole
>
>
>> Well, plans were sent to the list a couple weeks ago but I can send them
>> again no problem.
>> JPole Antenna
>> A JPole Antenna
>> In emergencies, you are likely to have to put up an antenna
> somewhere.
>> The
>> JPole described here is cheap, easily made, and works very well.
> Plus,
>> it's portable!
>> Home Are you ready to use your amateur radio communications skills
> in
>> a
>> real emergency?
>> This page, taken from various Internet sites, will help, by
>> enabling
>> you
>> to build your own roll-up Jpole antenna.
>> The 2-Meter 300 Ohm TV Twin-lead Roll-up J-pole.
>> As we all know, the antenna is the most important part of any
>> transmitter
>> system. It must be placed as high as possible, properly matched to
> the
>> transmitter, and designed to effectively radiate the power applied
> to
>> it.
>> The antenna that we are going to construct will be made from
> ordinary
>> 300-Ohm TV Twin lead wire. This wire is available at almost every
>> hardware, drug store, and other stores that carry such items as
>> telephone
>> extension cords.
>> In the diagram below you will see the construction details of the
>> antenna.
>>
>> Now, on to the step by step.
>> Tools: Ruler, Wire strippers, Wire Cutters, Soldering Iron.
>> Measure 54" of Twin lead and mark this spot with some masking
> tape.
>> Cut
>> the wire about 1 ½ inches longer than this measurement. If this
>> is
>> your
>> first attempt at building something, you may want to leave 4 " of
>> extra
>> wire on the piece you are working with. This will allow an
>> additional
>> attempt of the critical portion of construction.
>>
>> Remove the center insulation from the bottom 1-inch of twin lead.
>> Strip
>> the insulation off of the bottom section of twin lead (only the 1
>> ").
>> Connect the wire together at this point and solder.
>>
>> From the splice you just made at the bottom, measure up about 1 "
>> and
>> remove ½ " - ¾ " of insulation from each conductor. This is where
> we
>> will be attaching the coax.
>>
>> From the splice measure up one side 16 ½" . CHECK THE MEASUREMENT
>> TWICE.
>> Cut a gap on this side about ¼" wide. Be sure to remove the
>> conductive
>> material from the notch.
>>
>> From the splice, re-measure the total length to 54 " and trim the
>> top.
>>
>> Attach some coax to the opened area of the wire about 1 ¼" from
> the
>> splice. The shield of the coax MUST connect to the notched side.
>>
>> Attach a suitable connector on the end of the coax for your
>> transmitter
>> and GO!
>>
>>
>> Note: The antenna can be hung from almost anything using some
>> string
>> through a hole in the insulation about 1" from the top.
>>
>>
>> © Michael Willems 1999
>> Comments: [log in to unmask]
>>
>> ----- Original Message -----
>> From: "Colin McDonald" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Tuesday, February 15, 2005 4:39 PM
>> Subject: Re: Twin lead J pole
>>
>>
>> > John:
>> > send us a discription of the antenna and how you built it.
>> > Regards
>> > Colin
>>
>
|
