Guys,
I guess I really have a dumb SWR meter in comparison to yours. It
allows me to measure if my antenna is tuned to the freq (all our
antennas bought on the market are tuned, only handmade ones aren't and
they are close (probably within 4-5% if you follow the instructions).
Radio systems work best when the antenna system's impedance
matches the transmitter's output impedance as closely as possible.
The meter's standing wave ratio (SWR) function helps you trim your
antenna
to the precise length you need for the maximum transmitted power.
The meter's field strength function helps you position your antenna for
the best coverage and determine the effectiveness of changes you make to
your antenna, antenna cable, and transmitter. We already know the tail
is a superb place in the Europa.
If you have a radio that you suspect a low power or poor transmit but
can receive OK, it seems that one can check with an SWR but you will
still have to get another antenna and compare if the installed antenna
is not working. Plus, you must get to the back of the radio and hook
up a jumper get the meter hooked in anyway. The SWR is not going to
tell me anything other than good or bad on the installed antenna, so get
a good antenna off the shelf and compare is what works fast and easy.
Finally, if you suspect the radio is bad, (you should have bench checked
it, but what the heck=B8 it is a new radio and my experience in 12
panels they all worked), so if you suspect the radio, you have to bench
check it anyway. An Ohm meter will tell you if you have a bad cable and
the quick disconnect com lead at your panel back is your junction to the
spare antenna and you have your quick and dirty check.
Check your dials if you want, but it isn't going to be any faster.
That's why I have the spare antenna and build my panels to pop out fast.
My com 25 pin D sub connection from the panel to the airframe can be
hooked to a jack for a separate com check in minutes right on the bench.
By opening up the firewall access hole, and hooking to the backup
antenna is the quickest way to satisfaction.
Regards,
Bud
----- Original Message -----
From: David Lewendon<mailto:davidlewendon@me.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Sunday, May 29, 2011 7:29 AM
Subject: Re: Europa-List: Filser Radio problems
<davidlewendon@me.com<mailto:davidlewendon@me.com>>
Thanks for all the tips folks.
I will track down an SWR meter and check out the system.
I will let you know how I get on.
BW
David
On 29 mai 11, at 12:13, Frans Veldman wrote:
<frans@privatepilots.nl<mailto:frans@privatepilots.nl>
> >
>
> On 05/28/2011 11:09 PM, Bud Yerly wrote:
>
>> First check and ohm out your radio connections and coax attachment
to
>> your antenna. Check out the coax that the center wire and outer
>> shield
>> have no continuity.
>
> All too complicated and not necessary. Just borrow an SWR-meter, and
> see
> what it says. Broken wires, shorts, resonance problems, everything
> shows
> up with this simple test.
>
> There are many radio amateurs, find one and he probably loves to
> look at
> the installation of a real airplane.
>
> If there is anything else than the Europa recommended halve wave
> antenna
> in the tail closeout, I would scrap it and arrange such a halve wave
> antenna. Contradictory to common believe fed by marketroids, there
is
> nothing that beats a simple halve wave dipole for this application.
No
> antenna can have any gain over a dipole without introducing losses
in
> some area's. It is just like a light bulb, any gain you derive with
> reflectors and lenses will introduce dark spot in other directions.
A
> half wave is close to omnidirectional and only has two small "dark
> spots" straight up and straight down. Fortunately if you are
> overhead an
> ATC facility the "dark spot" is of no consequence as you are pretty
> close anyway.
> There is another reason to stay with a dipole: A dipole has a
certain
> impedance and it is exactly this impedance (50 ohms) that became the
> standard for the coax and output of the transmitter. Of course this
is
> no coincidence as the manufacturers know that the dipole is the best
> solution. Other antennas might have a different impedance, need a
> matching network (often built in and invisible to the user), and
often
> this matching network (consisting of coils and capacitors) breaks
> down,
> causing all sorts of problems.
>
> Just my 2 cents,
>
> Frans
>
>
>
>
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