for this particular antenna, the loading coil is fixed.
It is spaced windings up the fiberglass tube to about 6 inches from the top, 
where it is wound into a loading coil, so tight windings.  The windings are 
insulated from weather with shrink tubing or something similar.
You can adjust the top whip up and down, and I believe it may be able to be 
adjusted down into the top of the fiber glass tube a little way as well.
This adjustment is for different portions of the band I'm assuming.
power rating is 250W, but you can get a slightly bigger wire gage wound 
stick that will handle 1500W.
I payed $30, but they're listed on MFJ's website for $19.99 each...that 
includes resonator and whip.

these are monoband antennas only, though you can buy multi-band antennas of 
similar design from MFJ.
The series is the hamtenna or HF stick 1606 to 1680 line...mono band 
antennas for all ham bands from 6 meters up to 75/80...no 160 that I know 
of.
There is the MFJ1622 which will do 40M through 6M on one stick.  and there 
are a couple more like that, but I can't remember product numbers.
Go to
HTTP://www.mfjenterprises.com
and look at antennas.

the midland dual band antenna is a 5/8's wave on 2M and 440...with a closed 
trap in the middle.
73
Colin, V A6BKX
----- Original Message ----- 
From: "Gerry Leary" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 26, 2010 4:34 AM
Subject: Re: some new antennas to play with


> The next best was a 5/8 wave whip.  Can you tell me a little more about 
> the
> MFJ antenna?  I want to know things like can the loading coil be adjusted?
> Can it work on more then 1 band?  How much power can one use?  and how 
> much
> does it cost?
> ----- Original Message ----- 
> From: "Colin McDonald" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, March 26, 2010 12:12 AM
> Subject: some new antennas to play with
>
>
>>I picked up one of the MFJ hamtennas the other day.
>> I got the 20M resonator and whip.
>> It's essentially a 4 foot long  poll with wire wrapps up to a loading 
>> coil
>> near the top...then a 4 foot stainless steel whip attached on top.
>> the bass terminates in a 3/8's by 24 stud.
>> the whole assembly was pretty cheap so i figured i would try it out and
>> see
>> what sort of results I could get.
>> the shop didn't have any c clamp style mounts, so i'm fabricating
>> something
>> to atach to the balcony railing.  I picked up a bunch of 18 gage speaker
>> wire to use as counter poise as well.
>> I've also got a maggy mount with a 3/8's female connecter that i'm going
>> to
>> try out both mobile and perhaps at home if I can't find anything adequit
>> for
>> a mount.
>> I know I can probably get one of the c clamp style mounts online as well.
>> so far, with the antenna leaning against the wall inside on the fourth
>> floor, I am receiving far more on 20 meters than I was before.
>> I have the ground screw on the radio connected to the hot water heater
>> pipe
>> as a counter poise, but obviously it's far too long and not designed to
>> work
>> with the antenna...a few 16.5ft pieces of speaker wire should work well 
>> as
>> a
>> counter poise for now...attached at the bass of the antenna right at the
>> feed point.
>>
>> I also picked up a midland 18-325c dual band mobile antenna that i'm 
>> going
>> to use instead of the current quarter wave dual band on the vehicle.
>> Hopefully that will keep me into the repeater more consistently than the
>> quarter wave does now.
>>
>> 73
>> Colin, V A6BKX
>>
>