Hola Eddie and all,
I am using the spitfire array now since 10 years on 80m, with a single center
tower and
4 directional wires, switched as director/reflector.
The array is ok, giving some dB gain, f/s and f/b mostly nice.
It´s performance is a bit (vy little) below a 4square, but I like its wire
performance.
My friend Peter DF3KV gave my online description b4:
http://www.df9ox.com/e_afu80mtxant_spitfire.html
I will update my spitfire experiences this winter on my site, but will write
some parts below.
Well, answering questions for tuning it, I am in practice totally confirming
N6TR!
You need a source for exact tuning, some lambda distances apart.
Designers method and suggestions did not work.
With that I had been with some effects somewhere around 3650 kHz, but not at
that aimed
3510 kHz.
At that time I had no signal source for mobile action, so I tried it the very
long way.
Changing length and checking in the evening the f/b and gain results on the
band.
There are a lot signals on 80 in EU and outside EU, so it was possible, but
maybe not the
optimum.
It takes me a month, if I remember correct, and the result was greatly working
last years.
There are some lengths you can play with, and on 80m it is amazing that 10cm
changes a
lot!
The spitfire is worth to play with, my 2cent, but you need to know, with what
you are playing.
There is no free lunch. Some less vertical metal in the air gives you the
additional work of not
easy tuning that array. And, like ON4UN wrote, radials are vy important.
Some experiences, not yet described on my site:
- wire should be one which will not lengthen but strong enough for a stom.
After many years
my 4 long wires are broken in a storm 3 weeks ago. ( So I need that tuning
procedure again,
cause I will use not exact the same but stronger wires now)
- use a roll with a control-line at the highest point of the tower. Better for
changing high/length
of that long wire.
My english is not the best, I hope everybody understand what I tried to say.
My CW is mostly better :-)
Vy 73 de André DF9OX
Hello Dear Topbanders,
I had the chance to test
the Spitfire antenna during the CQWWSSB.
I installed it to cover initially one direction.
I had no problem to tune the elements to 1840 using a source signal
from the back. Reflector ended at 1855 and
director 2050, both tuned to max attenuation to the back as
suggested by designers.
At first I was delighted because I got f/b at ground level of more
than 20db across 25 Kc but surprise came when I
could not notice any improvement in the front gain switching on/off
the elements to medium distances (Brazil) or long
distance like Europe where it was pointed to (and same line of
Brazil).
I measured FS at 300 mts at ground level and I only detect 1db
maximun change
Reading ON4UN book, It looks like because of its configuration, the
main lobe is shifted upward a bit, so I could
think that because of that I measured very little at ground level
but not noticing any detectable change at
Brazil (3000Km) nor Europe (1Km) it really makes me wonder if
it is working at all.
Before changing the project to other direction, I would like to hear
your opinion and or suggestions.
Many thanks in advance Eddie, LU2DKT
_
Topband Reflector
_
Topband Reflector
