Battery Source

T o d d P a t t i s t writes:

Other advantages are that you can run the battery longer before it
gets too low, and for any switchmode DC-DC downconverters, such as I
use for my IPAQ's 5 volt requirements, you get less current draw and
the battery lasts longer (which it should since you've got more
stored energy). For me, the advantages of 14 volts outweigh the
disadvantages on my primary battery (it fits into the space
available), but not for my backup battery (the larger 14 volt
battery won't fit there.)

Switch mode converters have a gotcha built in; they are a constant
POWER device. When the voltage drops, they pull more current. If the
wiring resistance being too high is the cause of the low voltage, it
can get ugly very fast, and blow fuses.

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West Australia 6076
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wrote:
T o d d P a t t i s t writes:

Other advantages are that you can run the battery longer before it
gets too low, and for any switchmode DC-DC downconverters, such as I
use for my IPAQ's 5 volt requirements, you get less current draw and
the battery lasts longer (which it should since you've got more
stored energy). For me, the advantages of 14 volts outweigh the
disadvantages on my primary battery (it fits into the space
available), but not for my backup battery (the larger 14 volt
battery won't fit there.)

Switch mode converters have a gotcha built in; they are a constant
POWER device. When the voltage drops, they pull more current. If the
wiring resistance being too high is the cause of the low voltage, it
can get ugly very fast, and blow fuses.


That would take some grossly defective wiring. Perhaps a blown fuse would
be the wakeup call needed to fix the problem.

A more credible problem is a weak battery getting deep discharged because
of that. If a radio manufacturer were to actually build one of these
things in, they'd likely turn off the unit at some voltage, rather than
just letting it drag the battery down. But since they're concentrating
on the power market, that's not going to happen.

-Dave

Eric Greenwell wrote:
Udo Rumpf wrote:

It's possible you have a problem not related to the voltage; e.g.,
maybe the voltage is dropping well below the 11.8 volts when the
transmitter is keyed, or the radio is not functioning within
specifications.
Eric Greenwell


I have a 720A Dittle radio
Power requirements;
Receive .1 - .4 amps
Transmit (tone) 1.4 amps (.8 amps unmodulated)
The 11.8 volts I was referring to is before transmit.
If I remember correctly when the battery is fully charged
and I hit the transmit button the voltage drops from 12.7 to 12.2.
Udo

With the battery run down to 11.8 volts, measure the voltage right at
the radio connector while keying the transmitter for 5-10 seconds. If it
drops more than it does when the battery is fully (or nearly so)
charged, the problem might be the battery.

However....
I found a German manual for the ATR720A (and ATR70C in English) on the
Filser site (I think they took over the radios from Avionic Dittel). The
specifications don't make any mention of what voltage range the radio
will function over, so I suspect 12 volt battery operation wasn't on
their minds when it was designed. This appears to be an older design
radio, and likely is one that would benefit from 14 volt operation.

Absolutely true. But if you look hard enough, you'll see Filser claims
10.5 to 16 volts as an input voltage range for this radio. The same or
better as the current generation of super radios, which according to the
experts on RAS, supposedly were redesigned to work on lower voltage.



So, if it's not the battery, your choices seem to be a modern radio
(like the Walter Dittel FSG 2T I mentioned) or going to a 14 volt
battery pack. Or waiting till you get closer to the airfield to make
your call :^)


Or, he could get three or four large 12 volt batteries, and keep switching
between them, like a lot of people do. Certainly works for a while.
Particularly if you swap out batteries every year or two so you're using
only really fresh ones.

The FSG 2T very specifically says don't try to transmit with less than 11
volts, so I think that would be an expensive option that really wouldn't
help out. I suppose he could get a new Becker, but it's supposed to have
have at least 12.4 volts. Wonder where all these new super-radios are that
people keep talking about???? When you look at the facts, they just turn
out to be figments of some rather active imaginations.


-Dave

Microair M760 Transceiver.

"Input Voltage 10 - 16 Volts Warning damage will occur above 16
Volts"

"The operator should remember that the minimum operating voltage is 10
volts. This is the loaded voltage (ie the voltage when the radio is
transmitting). For battery operators, check the battery voltage level,
then press the PTT briefly to note the voltage drop. If the voltage
dips by more than 0.5 volts, change the battery before flying."

I enjoy my active imagination but I can also read a spec sheet.

David Kinsell wrote:

The FSG 2T very specifically says don't try to transmit with less
than 11 volts, so I think that would be an expensive option that
really wouldn't help out.

Contrary to what Dave writes, here is what the FSG 2T operation manual
says on page 50 of the FSG 2T Installation and Operation manual,
available on Wings&Wheels or Dittel's web site:

6.13 Emegency Operation

Without degradation the FSG 2T can be operated on a dc source between
11 Vdc and nearly 9 volts. This however will NOT reduce the TX
output level, RX sensitivity, and audio output power, due to internal
supply regulation. Below 11 volts the dc indicator flashes
continuously as low supply warning. Since the current drawn from the
battery will increase with lowered Dc supply voltage, the automatic
shut-down will speed-up.

If the supply voltage drops below 9 Vdc the FSG 2T swithces OFF
itself. This automatic feature avoids battery damage due to deep
discharging, even if the radio is left switched ON for months! This
is true for all types of 12 Vdc batteries.

If the battery recovers and voltage exceeds approximately 10.5 Vdc,
the radio returns to operation with the last used setting.

The above clearly shows why pilots have good experiences with Dittel
radios operating on 12 volt battery systems.

I suppose he could get a new Becker, but it's supposed to have have
at least 12.4 volts. Wonder where all these new super-radios are
that people keep talking about???? When you look at the facts, they
just turn out to be figments of some rather active imaginations.

I think I have found the explanation for the super-radios that we have
today. I stumbled across this reference recently:

Here’s the operating voltage matrix right out of DO-160 . . .

Voltage Category B

Maximum 15.1
Nominal 13.8
Minimum 11.0
Emergency 9.0


Modern avionics should operate over the voltage ranges cited for each
category of performance commensurate with the applicable system
voltage.

The table shows operation from 11.0 volts to 15.1, with emergency
operation down to 9 volts, essentially what the Becker and Dittel radios
(and probably others) specify. My short Google search for the standard
came up with an index

http://www.tuvamerica.com/industry/a...ce/emctest.cfm

and this

http://www.aeroelectric.com/articles/do160.html

that shows this specification is just one of many in the standard. I
don't know when the standard came into being, but I'm guessing it (or
the rationale behind it) is what drives manufacturers to produce radios
with a wide voltage tolerance. It's been around for a long time, as the
Dittel FSG 60 manual (March 1981) references the standard.

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Eric Greenwell
Washington State
USA

Andy wrote:
Microair M760 Transceiver.

"Input Voltage 10 - 16 Volts Warning damage will occur above 16
Volts"

"The operator should remember that the minimum operating voltage is 10
volts. This is the loaded voltage (ie the voltage when the radio is
transmitting). For battery operators, check the battery voltage level,
then press the PTT briefly to note the voltage drop. If the voltage
dips by more than 0.5 volts, change the battery before flying."

I enjoy my active imagination but I can also read a spec sheet.


You must have missed the part where it says "Input Voltage: Normal 13.8 Volts"
and "Emergency Min: 10.7"

http://www.microair.com.au/admin/upl...heet190905.pdf

The 10.7 emergency min was quoted for all revs of the radio up through
rev M.

The "Normal" 13.8 is what most people call Nominal. It's the only voltage
where the specs on power, distortion, etc are valid.

It's funny you should trot out the Microair as an example of some great
new radio supposed designed for 12 volt operation. In reality, it's been
one of the worst performers at low voltage transmit operation, regardless
of what the specs say.

It's just another radio designed for 14 volt operation, which works poorly
at low voltage, particularly on transmit. Same as we've had for at least
the last 20 years. Quoting specs of 10-16 volts with 13.8 nominal isn't
what I'd call news.

-Dave

Eric Greenwell wrote:
David Kinsell wrote:

The FSG 2T very specifically says don't try to transmit with less than
11 volts, so I think that would be an expensive option that really
wouldn't help out.

Contrary to what Dave writes, here is what the FSG 2T operation manual
says on page 50 of the FSG 2T Installation and Operation manual,
available on Wings&Wheels or Dittel's web site:


Utter baloney. The brochure for the radio, also available at the
W&W site, says:

"Is onboard supply sufficient? Observe onboard supply indicator
particularly during transmit, at least 11.0 Vdc must be shown!"


http://www.wingsandwheels.com/FSG2T%20Brouchure.pdf

Exactly which part is utter baloney; the manual or the brochure?

Tom

David Kinsell wrote:
Eric Greenwell wrote:

David Kinsell wrote:

The FSG 2T very specifically says don't try to transmit with less
than 11 volts, so I think that would be an expensive option that
really wouldn't help out.


Contrary to what Dave writes, here is what the FSG 2T operation
manual says on page 50 of the FSG 2T Installation and Operation
manual, available on Wings&Wheels or Dittel's web site:

6.13 Emegency Operation

Without degradation the FSG 2T can be operated on a dc source
between
11 Vdc and nearly 9 volts. This however will NOT reduce the TX output
level, RX sensitivity, and audio output power, due to internal supply
regulation. Below 11 volts the dc indicator flashes continuously as
low supply warning. Since the current drawn from the battery will
increase with lowered Dc supply voltage, the automatic shut-down will
speed-up.

If the supply voltage drops below 9 Vdc the FSG 2T swithces OFF
itself. This automatic feature avoids battery damage due to deep
discharging, even if the radio is left switched ON for months! This
is true for all types of 12 Vdc batteries.

If the battery recovers and voltage exceeds approximately 10.5 Vdc,
the radio returns to operation with the last used setting.



Utter baloney. The brochure for the radio, also available at the W&W
site, says:

"Is onboard supply sufficient? Observe onboard supply indicator
particularly during transmit, at least 11.0 Vdc must be shown!"

http://www.wingsandwheels.com/FSG2T%20Brouchure.pdf

Interested pilots should read the rest of the brochure. What Dave is
referring to is the section that begins:

"Function Checks:
If the Transceiver FSG 2T does not operate correctly, check the following:"

This is a trouble shooting section, not a normal operation section.
Making sure the pilot is using a battery with sufficient charge to test
the radio is very sensible, and a battery with less than 11 volt under
load is nearly exhausted, or there is a high resistance in the wiring or
the battery.

The Technical Data section of this brochure includes the specification:

"RF Output: = 5W into 50 ohms (carrier power), = 18 W (PEP) @ 9 to 16
VDC."

This is the same as the manual. I don't see how it can be stated any
more clearly that this radio will function at full power down to 9
volts. It does not mean your radio will be able to transmit with a 12
volt battery that only has 9 volts left on it. The FSG 2T manual makes
this clear, and has a table with estimated times of operation as your
battery discharges below 11 volts. How low the battery voltage can go
and still allow you to transmit depends very much on the size and
condition of your battery.

Question: Why do Dittel, Becker, and Filser have such broad input
operating voltage ranges?

Answer: "These voltages ranges are a European requirement" - Eric
Pscherer, Dittel engineer, in a recent phone call to me. Further, he
stated the new requirement is now 9.1 volts to 16.1 volts, and that
these ranges are easy to achieve with the power supplies now available.
In the past, he said, switching supplies were too noisy (electrically)
to use in receivers, but that is not the case now.

Question: What are the European requirements?

Answer: The requirements for voltage range and many others parameters
are contained in the RTCA/DO-160E document, "Environmental Conditions
and Test Procedures for Airborne Equipment", published by RTCA, Inc., in
Washington, DC. Anoraks will want to peruse this large (778 page, 20 MB
pdf file!) and mind-numbing document, a 2004 draft of which may be
downloaded here (found by Tom Seim):

http://pr.erau.edu/~lyallj/SC135/D-to-E.pdf

or you can purchase a copy of the current document from RTCA for a few
hundred dollars. Incidentally, the document covers far more than just
radios.

The voltage range section for Category B, which our radios fit into, is
in 16.6.1 (Normal Range), and a few pages down you will find the
values for Abnormal Range.

What it means for glider pilots is our European radios are designed to
operate properly on a 12 volt battery, even one that is essentially
exhausted. Motorglider pilots will be delighted to know the standard has
stringent requirements for withstanding voltage surges produced by
engine driven generating systems, and starting their engine with the
radios on (the usual case during an in-air restart, at least for me!) is
very unlikely to cause any damage.

Question: Why the heck does DO-160D ask for such a voltage range when
the radio will be operating on 13.8 volts all the time?

Answer: I can only guess that it is to ensure operation in situations
where the generating system has malfunctioned (alternator gone bad,
drive belt broken, etc) and the battery, or a much smaller backup power
source, has to supply power. Airplane pilots tend to be very dependent
on their radios and other instruments, and someone flying IFR is not
going to be happy if the instrument quits before the battery does.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Hi Eric,

Excellent research and presentation of pertinent data!

Thanks,

Paul Remde

"Eric Greenwell" wrote in message
...
David Kinsell wrote:
Eric Greenwell wrote:

David Kinsell wrote:

The FSG 2T very specifically says don't try to transmit with less
than 11 volts, so I think that would be an expensive option that
really wouldn't help out.


Contrary to what Dave writes, here is what the FSG 2T operation
manual says on page 50 of the FSG 2T Installation and Operation
manual, available on Wings&Wheels or Dittel's web site:

6.13 Emegency Operation

Without degradation the FSG 2T can be operated on a dc source
between
11 Vdc and nearly 9 volts. This however will NOT reduce the TX output
level, RX sensitivity, and audio output power, due to internal supply
regulation. Below 11 volts the dc indicator flashes continuously as
low supply warning. Since the current drawn from the battery will
increase with lowered Dc supply voltage, the automatic shut-down will
speed-up.

If the supply voltage drops below 9 Vdc the FSG 2T swithces OFF
itself. This automatic feature avoids battery damage due to deep
discharging, even if the radio is left switched ON for months! This
is true for all types of 12 Vdc batteries.

If the battery recovers and voltage exceeds approximately 10.5 Vdc,
the radio returns to operation with the last used setting.



Utter baloney. The brochure for the radio, also available at the W&W
site, says:

"Is onboard supply sufficient? Observe onboard supply indicator
particularly during transmit, at least 11.0 Vdc must be shown!"

http://www.wingsandwheels.com/FSG2T%20Brouchure.pdf

Interested pilots should read the rest of the brochure. What Dave is
referring to is the section that begins:

"Function Checks:
If the Transceiver FSG 2T does not operate correctly, check the
following:"

This is a trouble shooting section, not a normal operation section. Making
sure the pilot is using a battery with sufficient charge to test the radio
is very sensible, and a battery with less than 11 volt under load is
nearly exhausted, or there is a high resistance in the wiring or the
battery.

The Technical Data section of this brochure includes the specification:

"RF Output: = 5W into 50 ohms (carrier power), = 18 W (PEP) @ 9 to 16
VDC."

This is the same as the manual. I don't see how it can be stated any more
clearly that this radio will function at full power down to 9 volts. It
does not mean your radio will be able to transmit with a 12 volt battery
that only has 9 volts left on it. The FSG 2T manual makes this clear, and
has a table with estimated times of operation as your battery discharges
below 11 volts. How low the battery voltage can go and still allow you to
transmit depends very much on the size and condition of your battery.

Question: Why do Dittel, Becker, and Filser have such broad input
operating voltage ranges?

Answer: "These voltages ranges are a European requirement" - Eric
Pscherer, Dittel engineer, in a recent phone call to me. Further, he
stated the new requirement is now 9.1 volts to 16.1 volts, and that these
ranges are easy to achieve with the power supplies now available. In the
past, he said, switching supplies were too noisy (electrically) to use in
receivers, but that is not the case now.

Question: What are the European requirements?

Answer: The requirements for voltage range and many others parameters are
contained in the RTCA/DO-160E document, "Environmental Conditions and Test
Procedures for Airborne Equipment", published by RTCA, Inc., in
Washington, DC. Anoraks will want to peruse this large (778 page, 20 MB
pdf file!) and mind-numbing document, a 2004 draft of which may be
downloaded here (found by Tom Seim):

http://pr.erau.edu/~lyallj/SC135/D-to-E.pdf

or you can purchase a copy of the current document from RTCA for a few
hundred dollars. Incidentally, the document covers far more than just
radios.

The voltage range section for Category B, which our radios fit into, is in
16.6.1 (Normal Range), and a few pages down you will find the values for
Abnormal Range.

What it means for glider pilots is our European radios are designed to
operate properly on a 12 volt battery, even one that is essentially
exhausted. Motorglider pilots will be delighted to know the standard has
stringent requirements for withstanding voltage surges produced by engine
driven generating systems, and starting their engine with the radios on
(the usual case during an in-air restart, at least for me!) is very
unlikely to cause any damage.

Question: Why the heck does DO-160D ask for such a voltage range when the
radio will be operating on 13.8 volts all the time?

Answer: I can only guess that it is to ensure operation in situations
where the generating system has malfunctioned (alternator gone bad, drive
belt broken, etc) and the battery, or a much smaller backup power source,
has to supply power. Airplane pilots tend to be very dependent on their
radios and other instruments, and someone flying IFR is not going to be
happy if the instrument quits before the battery does.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA