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trigo(at)mail.telepac.pt
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 Posted: Mon Jul 29, 2013 10:17 am Post subject: 14V / 28V converter |
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Well, the spec sheet of the TRIG radio mentions 2.4A when transmitting, so I suppose that a 50W converter will still not be enough…
By the way, what would happen if I put an under rated converter, would it fry after a couple of radio transmissions?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:55
Para: aeroelectric-list(at)matronics.com
Assunto: Re: 14V or 28V
Carlos,
You should start with the spec sheet of the radio that you want to use to determine its current draw. Then you can use the formula I provided to calc the required power. I would then select a power converter that gives you a significant safety margin of power; perhaps at least 20 percent greater power than your calculation indicates.
Let's hope someone on this List has done this before and can recommend a device that they have used successfully.
From: Carlos Trigo <trigo(at)mail.telepac.pt (trigo(at)mail.telepac.pt)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Monday, July 29, 2013 10:21 AM
Subject: RE: 14V or 28V
Jeff
Thanks for calling my attention.
In that case, I suppose the adequate should be this one
http://aconinc.com/index.php?route=product/product&path=1_12400_12406&product_id=436
or this one
http://aconinc.com/index.php?route=product/product&path=1_12800_12807&product_id=531
Is that so?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:04
Para: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Assunto: Re: 14V or 28V
You have to be careful when selecting power converters of this type.
Be aware of the power requirements. If the radio in question only draws 2 amps at transmit then that's 48 watts of power, P = IE (watts = amps x volts) that the converter must deliver when you key the mic. The one referenced is only 13 watts and would be inadequate.
From: R. curtis <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Sunday, July 28, 2013 5:15 AM
Subject: Re: 14V or 28V
--> AeroElectric-List message posted by: "R. curtis" <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
| Quote: | Still didn't get any answer about the second part of my initial query.
How about keeping the 14V system and using a 14/28 voltage converter to feed
the radio?
|
You could use something like this. Just make sure that you
size it to supply enough 24 volt power for your needs.
This will connect to your 12 volt system and supply 24 volts
to your radios.
http://aconinc.com/index.php?route=product/product&path=1_12400_12402&product_id=136
Using this would mean that there is no other mod required
to your aircraft electrical system thus maintaining a standard
12 volt system.
Roger
--
Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
<br ========================
0123456789012345
[quote][b]
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jluckey(at)pacbell.net
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| Posted: Mon Jul 29, 2013 10:57 am Post subject: 14V / 28V converter |
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By the way, what would happen if I put an under rated converter, would it fry after a couple of radio transmissions?
Lots of bad things:
1. Transmitted signal would be weak or non-existant
2. Possible damage to radio due to brown-out condition
3. You might fry the power supply or it may have built-in overload protection and simply shut-off
4. you might induce total plutonic reversal and cause a rift in the space-time continuum (oh, wait - that's only if you "cross the streams"
From: Carlos Trigo <trigo(at)mail.telepac.pt>
To: aeroelectric-list(at)matronics.com
Sent: Monday, July 29, 2013 11:15 AM
Subject: RE: AeroElectric-List: 14V / 28V converter
Well, the spec sheet of the TRIG radio mentions 2.4A when transmitting, so I suppose that a 50W converter will still not be enough…
By the way, what would happen if I put an under rated converter, would it fry after a couple of radio transmissions?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:55
Para: aeroelectric-list(at)matronics.com
Assunto: Re: 14V or 28V
Carlos,
You should start with the spec sheet of the radio that you want to use to determine its current draw. Then you can use the formula I provided to calc the required power. I would then select a power converter that gives you a significant safety margin of power; perhaps at least 20 percent greater power than your calculation indicates.
Let's hope someone on this List has done this before and can recommend a device that they have used successfully.
From: Carlos Trigo <trigo(at)mail.telepac.pt (trigo(at)mail.telepac.pt)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Monday, July 29, 2013 10:21 AM
Subject: RE: AeroElectric-List: 14V or 28V
Jeff
Thanks for calling my attention.
In that case, I suppose the adequate should be this one
http://aconinc.com/index.php?route=product/product&path=1_12400_12406&product_id=436
or this one
http://aconinc.com/index.php?route=product/product&path=1_12800_12807&product_id=531
Is that so?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:04
Para: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Assunto: Re: 14V or 28V
You have to be careful when selecting power converters of this type.
Be aware of the power requirements. If the radio in question only draws 2 amps at transmit then that's 48 watts of power, P = IE (watts = amps x volts) that the converter must deliver when you key the mic. The one referenced is only 13 watts and would be inadequate.
From: R. curtis <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Sunday, July 28, 2013 5:15 AM
Subject: Re: 14V or 28V
--> AeroElectric-List message posted by: "R. curtis" <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
| Quote: | Still didn't get any answer about the second part of my initial query.
How about keeping the 14V system and using a 14/28 voltage converter to feed
the radio?
|
You could use something like this. Just make sure that you
size it to supply enough 24 volt power for your needs.
This will connect to your 12 volt system and supply 24 volts
to your radios.
http://aconinc.com/index.php?route=product/product&path=1_12400_12402&product_id=136
Using this would mean that there is no other mod required
to your aircraft electrical system thus maintaining a standard
12 volt system.
Roger
--
Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
<br ========================
012345678901234
[b][b] [quote][b]
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billp(at)wwpc.com
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| Posted: Mon Jul 29, 2013 3:30 pm Post subject: 14V / 28V converter |
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So, it depends. Assume the wattage rating is the output wattage and not the input wattage (being charitable here). A 50W converter is designed to put out 1.8A at 28V. It probably operates over an 11V-15V input range. So if it's 80% efficient it would use about 62W of power to make the 50W on the output. A designer has to figure that at 11V input the transistors that switch the DC have to be good for something more than 5.7A. At 15V They only need to do 4.2A and something slightly less than that at the nominal 14V. What usually happens is that these inverters use pulse duty cycle of these input transistors to do the raw regulation of the output voltage. Once the maximum duty cycle is reached the power in the circuit is at maximum and if more current is required the voltage has to fall.
The bad news is that the power supply in the transceiver is also a switch mode one (cause they're smaller, cheaper and lighter than anything else) so it wants to keep the voltages inside the radio at the designed conditions. So as the input voltage falls, it increases it's duty cycle which draws more current at the input. I think you can see where this is headed.
If the radio is designed well, it will blow an internal fuse or self protect and shut down (probably requiring an avionics bus power cycle to reset it). If it's pourly designed the radio's power supply will let the internal voltages fall below the designed values making the transmitter frequency unstable and creating all kinds of other interference products in the transmitter. My guess that would be caught in the FCC independent lab testing and it wouldn't get certified. So probably the power supply in the radio is designed right.
You're asking that the converter operate at 130% of it's rated power? Most designers cut some slack in their designs so you could get away with a little. Most sales/marketing people want the numbers to sound big though. So, if they say it's a 50W converter, that might be the input power. If the converter is 80% efficient, that's 40W on the output. About 1.4A and your radio is then 170% of the rated load. 70% is way to expensive to design in for manufacturing slack. Of course your converter may have used it's manufacturing slack in manufacturing...
I have had some sad experiences with one US manufacturers radio that simply burn up the internal power supply in the radio in response to too low an input voltage. It use to be that making the new engineers design the power supplies was the thing to do because it was the least fun.
If you could figure out a way to limit the current in the converter, you could charge a very small 28V battery from the converter and since the transmitter duty cycle is low you'd just transmit using the battery power to bridge the time you're transmitting and the battery would charge back up using surplus capacity when the radio is in receive.
Or you could get the 14V Trig radio that puts out 6W instead of 12W. That's an insignificant (-3dB) power decrease and oh so much simpler a solution. A better antenna will make that much difference. If you were in outer space the 12W would go twice as far but most of us don't travel in outer space and we get over the horizon before we run out of power.
There is no limitation on the size of the transmitter based on input voltage. I have a VHF ham radio that will deliver 100W and it runs on my 13V car battery. Draws a lot of amps doing it though. The power supply inside the radio takes care of making the RF parts happy at whatever power level is desired.
Bill
On 7/29/13 11:15 AM, Carlos Trigo wrote:
[quote] v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} <![endif]--> <![endif]--> <![endif]-->
Well, the spec sheet of the TRIG radio mentions 2.4A when transmitting, so I suppose that a 50W converter will still not be enough…
By the way, what would happen if I put an under rated converter, would it fry after a couple of radio transmissions?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:55
Para: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Assunto: Re: 14V or 28V
Carlos,
You should start with the spec sheet of the radio that you want to use to determine its current draw. Then you can use the formula I provided to calc the required power. I would then select a power converter that gives you a significant safety margin of power; perhaps at least 20 percent greater power than your calculation indicates.
Let's hope someone on this List has done this before and can recommend a device that they have used successfully.
From: Carlos Trigo <trigo(at)mail.telepac.pt (trigo(at)mail.telepac.pt)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Monday, July 29, 2013 10:21 AM
Subject: RE: 14V or 28V
Jeff
Thanks for calling my attention.
In that case, I suppose the adequate should be this one
http://aconinc.com/index.php?route=product/product&path=1_12400_12406&product_id=436
or this one
http://aconinc.com/index.php?route=product/product&path=1_12800_12807&product_id=531
Is that so?
Carlos
De: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:04
Para: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Assunto: Re: AeroElectric-List: 14V or 28V
You have to be careful when selecting power converters of this type.
Be aware of the power requirements. If the radio in question only draws 2 amps at transmit then that's 48 watts of power, P = IE (watts = amps x volts) that the converter must deliver when you key the mic. The one referenced is only 13 watts and would be inadequate.
From: R. curtis <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Sunday, July 28, 2013 5:15 AM
Subject: Re: 14V or 28V
--> AeroElectric-List message posted by: "R. curtis" <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)>
> Still didn't get any answer about the second part of my initial query.
> How about keeping the 14V system and using a 14/28 voltage converter to feed
> the radio?
You could use something like this. Just make sure that you
size it to supply enough 24 volt power for your needs.
This will connect to your 12 volt system and supply 24 volts
to your radios.
http://aconinc.com/index.php?route=product/product&path=1_12400_12402&product_id=136
Using this would mean that there is no other mod required
to your aircraft electrical system thus maintaining a standard
12 volt system.
Roger
--
Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
<br ========================
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
[b] 6 [/b][/b][b]
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