Topband: Spitfire question

[df9ox at gmx.de]

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 (>10000Km) 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