Which Transponder?

A year ago there was a question about which transponder might be
preferable in gliders. Most of the responses debated *whether* a
transponder was a good idea, and no one had any comparative
experience.

I'm wondering, with another year under our collective belts, what
users' experiences with the various currently-available transponders
might be -- Microair, Becker, Filser.

Thanks,
DJ

I installed a Becker 4401 175w Transponder and A-30
Encoder in my DG808B last winter and added 7ah of additional
battery. Since this self launcher comes with a large
battery set the extra capacity may not be necessary.
At my normal flying location the transponder is responding
almost constantly and I have flown as long as 4 hours
with no noticeable loss of power.


At 06:48 21 October 2004, Danl Johnson wrote:
A year ago there was a question about which transponder
might be
preferable in gliders. Most of the responses debated
*whether* a
transponder was a good idea, and no one had any comparative
experience.

I'm wondering, with another year under our collective
belts, what
users' experiences with the various currently-available
transponders
might be -- Microair, Becker, Filser.

Thanks,
DJ

Hi:

I am just completing the wiring for my new Becker transponder. The average
current draw is fairly low, so it is not difficult to manage from the
standpoint of battery power.

There are a number of reasons to use a transponder. The best reason is
safety. Air Traffic Control will be able to identify you and alert others
to avoid running into you. Avoiding collisions is good. For wave soaring
over 18,000 feet, it is also good.

I installed mine into a motorglider and intend to fly into Class D airspace
and utilize control towers. This makes life much simpler.

I also have a Collision Avoidance System which utilizes transponders to
alert me to other traffic.

Primary drawback is that it takes current and money. But, I am worth it.

Colin N12HS


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Hi DJ
It is amazing how themes posted immediately morph into mostly
completely unrelated subjects on this bulletin board. I will attempt
to answer your question with a couple of comments.
I have an old thumbwheel Terra in my DG800B and a Becker in my Stemme
S10-VT. Both work fine and have been reliable. Both aircraft have
larger batteries than a regular glider and I have never had a problem
running down a battery even after several hours of transponder
operation. Flying often close to Reno Intl Airport and in the Bay Area
I usually monitor ATC frequencies (RNO Approach and Bay Approach)and
feel comfortable that ATC has always correctly identified my position
and correct height.
Which transponder do I prefer? The Becker because it shows what
altitude it is transmitting, is easier to set a squawk code and fits a
standard hole in the instrument panel. However I would unconditionally
recommend either. If you fly anywhere near a busy airport/airway a
transponder is mandatory! Safety is no accident.
Dave

(Danl Johnson) wrote in message om...
A year ago there was a question about which transponder might be
preferable in gliders. Most of the responses debated *whether* a
transponder was a good idea, and no one had any comparative
experience.

I'm wondering, with another year under our collective belts, what
users' experiences with the various currently-available transponders
might be -- Microair, Becker, Filser.

Thanks,
DJ

No personal experience, but as far as I know, only Filser is selling a
mode S transponder suitable for sailplanes right now.

Stefan

I installed a Becker 4401 (175 watt) transponder and A-30 altitude
encoder in my LS-4a last spring. Since my ship is registered
"experimental", I did the work myself. The installation took a couple
of days of fussing, but checked out perfectly (except the altitude
encoder required a bit of re-callibration). Wings and Wheels can
provide you with everything you need.

Since your LS-3 is not carbon fiber, you can install the antenna
**inside** the fuselage. After considering many options, I mounted the
antenna plate against two bulkheads directly behind the wheel well
case with the antenna pointing down. I was told this would be
difficult, but in practice it was not so hard. If you want details,
send me an email, and I'll try to be helpful.

I converted to a 12 AH battery after installing the transponder, and
have never come close to draining it on four-five hour flights.

I sometimes fly out of AirSailing north of Reno in the approach
airspace for Reno International. My transponder is interrogated
constantly, and I must say, it provides me with a much higher comfort
level to have it aboard. I highly recommend it if you ever fly in
congested airspace.

not in the USA.....
it still has not received any US FAA approvals
tim

"Stefan" wrote in message
...
No personal experience, but as far as I know, only Filser is selling a
mode S transponder suitable for sailplanes right now.

Stefan

In NZ a transponder is getting just about a requirement as our
CAA is a ##### !
The dept is introducing airspace restrictions that are totally
unwarranted as similar airspace traffic densities in other countries
don't even have controllers let alone the regime that we have here.
This is mainly in the north island the south island has fewer traffic
zones so is largely unregulated.
The controllers are sitting at a centre 800 kms away
(in the name of centralisation) from the biggest traffic area near
where I fly.
Enough of my ranting , On the subject I have been offered a Terra
transponder, any feedback on this unit .
gary


"Danl Johnson" wrote in message
m...
A year ago there was a question about which transponder might be
preferable in gliders. Most of the responses debated *whether* a
transponder was a good idea, and no one had any comparative
experience.

I'm wondering, with another year under our collective belts, what
users' experiences with the various currently-available transponders
might be -- Microair, Becker, Filser.

Thanks,
DJ

Danl Johnson wrote:

A year ago there was a question about which transponder might be
preferable in gliders.

I asked this question about a year ago. I have since installed a 175W
Becker into our LS3 together with an Ameriking AK-350 encoder.

I'm wondering, with another year under our collective belts, what
users' experiences with currently-available transponders
might be -- Microair, Becker, Filser.

The Becker works very neatly. A nice feature is that it displays the
flight level reported by the encoder on the display so when you are
talking to ATC you can report flight level from the transponder. (ATC
don't like it when the pilot reports altitude from an altimeter that
reads slightly differently to the data transmitted from the encoder).

I passed over the Microair, just from a point of staying with a known
brand. There is a Microair flying at our club and it appears to work.

In hindsite I would have a much closer look at the Filser S mode unit.
It was not available when I ordered ours. It is much more expensive but
it has its own internal encoder which help offsets it's higher cost. I
am not sure that it will be support the new transponder protocols that
are still on the drawing board, so its life time to obsolescence may
not be that much longer than the Becker. I fly in South Africa and S
mode is not likely to be a requirement here for a long time.

I considered looking for a 2nd hand Terra unit. But there are not many
around, and if anything goes wrong with them they are very difficult to
get fixed. There a number of these in our club and some pilots have
experienced failures of the gas plasma display.

When you have decided what to buy, you are left with 3 decisions:

- What to do about power:

I put in a 2nd 7Ah battery. I got fancy and split the radio/vario and
transponder power circuits. Each runs off one battery but there are 2
changeover switches which allow everything to be run off either of the
two bateries. Power to our Volkslogger is from both batteries, via a
couple of diodes, which allow it to automatically draw current from
whichever batter has the highest voltage. (No bulky capacitor and no
lost traces!)

One 7Ah battery should happly power everything, including the
transponder for about 5 hours. The 2nd one is necessary, because you
only discover when the first one has reached the end of its life the
hard way. The changeover switch allows you to finish that flight
gracefully.


- Where to mount the antenna.

I used a cheap dongle antenna. I put ours inside the fuselage behind the
mainwheel. Access was tricky but it is a nice safe location. If you
have a motor glider or a carbon fuselage, you may need to mount a
streamlined antenna under the fuselage. Then you should move it far
enough off the centreline so that it does not get damaged during an out
landing or while pushing the fuselage into the trailer. Some gliders in
our club have transponder antennae mounted behind the instrument panel.
There is a debate as to the effect of the radiation on the pilot, but I
think another issue is the blind spot created by the blanking effect of
the panel and the pilot.


- Where to mount the encoder.

Everybody knows where that neat new 57mm instrument will fit in their
panel but only later do you think of mounting the encoder. This was
much bulkier than I expected. I shoe-horned it into a gap behind the
panel between the gas strut, wiring and instrument tubing and made a
fancy bracket to hold it there. The other option was under the floor. I
also investigated a volume above the rudder pedals, but my partner has
long legs and big feet.


Was it worth it? Well I will tell you when I get my diamond hight!


Ian

I wrestled with a transponder antenna for my fabric covered motorglider. I
did not want an external antenna, but needed vertical polarization.

Finally decided on a flush disc antenna. This design came from the John
Kraus antenna handbook, so I will need to build in myself as there is none
available. But it will mount on the inside surface of the belly of my
motorglider. Just in the process of fabricating one.

I also purchased a Becker and it should do nicely.

Colin N12HS


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