24 volt power supply in a 12 volt aircraft.

Hi folks,

I have access to a very good aircraft radio, at a very reasonable price.
The problem is that the aircraft that needs the radio is a 12 volt system,
and the radio is 24volt.
Are there any reasonably inexpensive options? I guess we could add
another 12 volt battery, charge them in parallel, and take power off in
series. Are there step up voltage modules out there that would support a 5
watt transmitter?
Any Ideas?

Thanks in advance,

Al G

 

The most direct method of powering your radio would be to get a 12V-24V DC-DC
converter. That method involves connecting the input of the converter to the
12V power system in the airplane, and then connecting the output of the
converter to the power wires on your radio. Simple, easy, but, alas, likely to
be quite expensive. I did a quick search of some of the major parts houses, but
came up empty for anything close to your requirements.
The next best, and probably the cheapest and easiest to buy at retail, is to buy
a 24V DC power supply and a small (50W or so) DC-AC inverter. You can buy a
power supply like the one here
http://www.mpja.com/productview.asp?product=15737+PS. Very reasonably priced.
And at that price, I'd advise to buy a couple... have a spare, just in case.
The inverter can be found at dept stores such as Wal-Mart. You don't need
anything more powerful than about 15 watts, but most likely the smallest
inverter you will find is around 50 watts. This is OK, since the radio will use
only the power it needs, and modern inverters are pretty efficient, so you won't
be wasting a terrible amount of power.
At 5W RF power, the radio probably needs only about 10W or so from the power
source, so don't go looking for something that can power a small naval vessel.
{:>)
Cheers!!!
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.

 

Yes, there are.
I'm guessing 5W is broadcast power, how many amps does the radio need.

http://www.kemo-electronic.com/en/module/m029/index.htm

I think they can be paralleled safely if one isn't enough

Bye.
Jasen

 

Those are intreresting converters, but unfortunately, on the home page, "NO SALE
TO PRIVATE PERSONS!".

That kinda puts them out of reach

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.

 

Are there any restrictions on doing this? Regulations?

http://www.powerstream.com/dc24.htm

ED1075-24 DC to DC Converter

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I don't know the draw(amps), the specs didn't say. See:
http://www.seaerospace.com/king/ky96a.htm

The DC->DC converter looks like it might work.

Al G

 

Since they make a 12 V model, have you considering modifying yours to the 12
V design?


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I've got two of them, but no I've stopped at the case.

Al G

 

sorry, they are available elsewhere.... here's where I first encountered them:

http://jaycar.co.nz/productView.asp?ID=AA0264

 

b vry careful of the grounding required for this setup.

you must generally have a secure and patent ground from the radio to the
chasssis (of the plane) to provide efficeint RF output and reliable receiver
sensitivity.

and as the antenna xmit/receive internal circuitry attempts to switch from
full xmit power and then back to recive mode, ther may be some offsetss
generated.

as the power may be adaptable when just clamping the radio ground to the
same 12 volt ground, the inter mingling systems may genereate some dc
offsett at the ground level.

i would just find a convenient place to lash a good extra 12v battery in
place and then attach the radio to the battery plus, and the battery
negative to the planes 12dc power system. maintenance of the battery should
be minimal.

if this is your only comms unit onthe plane, be sure u alway file a good
flight plan ;-))

while all this may save u a few buks, you really should consider getting a
brand new plane to make sure your radio is correctly installed ;-))

 

Thanks, I am inclined to agree. I can always sell this one, and buy a 14
volt system.

Al G

 

A cheap and simple solution might be to just buy a power supply that gives 24v from
a 12v input. For example Altronics sell a 'Car Laptop Power Supply' which provides
a choice of output voltages from 15v to 24v fully regulated at up to 3.5 amps (from
a 12v input) for only $49.95

Catalog number M8626

www.altronics.com.au

I should think other stores like DSE and Jaycar will have similar units on offer

David

 

Do you hold an A&P certificate to legally make such
modifications, and sign off in the maintenance logbook
of said aircraft ?

what's the local FSDO have to say about it ?

unless you enjoy receiving FAA enforcement letters,
you should review FAR part 43 of the regulations &
the relevant references to other chapters that delineate
what you can & can't do.