[UK-CONTEST] CG-3000 vs MFJ-974HB on 160, 80, 40m band

[Berni G0IDA]

My best approach to your problem would be option 3 but cut the antenna
10% less on 160m so that on 160m you don't have a very high impedance
at the feed point which might give you a problem tuning the ATU.
Shortening it by 10% is unimportant to antenna performance.

Also
make sure when you are feeding the antenna with 450 Ohm twin feeder you
cut the feeder NOT to a 1/4 wave or 1/2  on any freq as this will act
as a transformer and again present very high impedances which the ATU
may or may not cope with.

Since you will be running no more than
300W SSB 150W CW (MFJ-974 ATU rating) bringing open wire feeder into
the shack and into the ATU is not an issue either, providing it's not
running around the shack but is going through the wall and straight
down into the MFJ.

The advantages with option 3 is that it's a
balanced system and there will be some gain on the higher frequencies.
It is also more efficient than the other options, less loss on the
feeder run compared to coax.
Also less expensive as putting out an effective grounding system for your "L" antennas will probably cost many times more than 2 x 40m.

Disadvantages,
well, with the vertical section of the other options you will have
vertical radiation which may be to your advantage if you are aiming to
chase DX. DX is of course also possible with the 2 x40m.

I have
put up many antennas like the one I have just described on
many-a-contest and at home and have never had any problems with good DX
on 40m & 80m but less on 160m.

Good luck and let us know what you decided to do.

Regrads,

Berni
G0IDA

--- On Wed, 11/12/08, Samir Popaja, 7S7V (SM7VZX) <7s7v at adamomail.se> wrote:
From: Samir Popaja, 7S7V (SM7VZX) <7s7v at adamomail.se>
Subject: [UK-CONTEST] CG-3000 vs MFJ-974HB on 160, 80, 40m band
To: uk-contest at contesting.com
Date: Wednesday, November 12, 2008, 7:48 AM

CG-3000; http://www.arraysolutions.com/Products/cg_3000.htm

MFJ-974HB; http://www.mfjenterprises.com/Product.php?productid=MFJ-974HB 

Hello, 

I need to solve my problem on low bands; 160, 80 and 40m with one antenna. 

These are my possible solutions (which is better according to you antenna/
tuner knowledgeable people).

The antenna will be used primary for contest.

1. Inverted L (15m + 25m) with radials, feeding with coaxial cable and
CG-3000 in feedpoint 

2. Dipole (2 x 20m), via 450 ohm open line and MFJ-974HB, on 160m the
antenna will be used like T vertical and ground (@20m) 

3. Dipole (2 x 40m), via 450 ohm open line and MFJ-974HB (@20m) 

4. Inverted L (15m + 25m) with radials, via 450 ohm open line and MFJ-974HB 


*What's the behave of solution 2. and 3. against halfwave dipole feed via
50ohm coax on 40 respective 80m with same height, @20m? 


Thank You for all answers/ suggestions. 

SM7VZX 

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