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25W pallet amp @ 12V supply / supposed load?

 
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25W pallet amp @ 12V supply / supposed load?
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honsey
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Post 25W pallet amp @ 12V supply / supposed load? Reply with quote
Hello there,

when I power the 25W pallet amp with 12V, what's the supposed load in normal conditions?

In my setup — dummy load connected — I do measure 1.7A... do I have to check my connections again?

Thank you,
Hans
Mon Jan 19, 2015 9:14 pm View user's profile Send private message
pcs
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This indicates that the drive power is too low.


At 25W this pallet will draw more, 3-4A depending on frequency.

You are probably dealing with output of around 10-15W.

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Tue Jan 20, 2015 11:48 pm View user's profile Send private message Visit poster's website
honsey
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I think so too... I first thought it might be some connection-problem to the antenna, fixed it but still get low output power.

As you could see in my other post I'm building 10 transmitters. One of them is actually drawing 3.8A — which makes me very happy because it feels like 25W

But it also makes me sad, because I use the same hardware in all the transmitters. Thus — their output power is so diverse In the meantime I measured them all — most of them are around 1.0 to 1.5A, some around 2.0, some below 1.0A.


PS: Thank you for your email!
Wed Jan 21, 2015 1:13 am View user's profile Send private message
pcs
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What you need is a feedback loop, you need to be able to measure output power and adjust drive level to always have 25W and not more.

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Marko - PCS Electronics
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Turn your PC into a FM radio station!
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fax +386 4 2316 128
Wed Jan 21, 2015 12:24 pm View user's profile Send private message Visit poster's website
honsey
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...right now I'm not that concerned about exceeding the 25W

I think I'll try to draw up where/how my setup is grounded.. I have the strong feeling that I made a big mistake with that.
Wed Jan 21, 2015 12:42 pm View user's profile Send private message
honsey
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I tried to sketch out, how the ground situation in the case (aluminium, eloxated) is — as far as I know (green = grounded case):


Filter, Amp are soldered to the case. = grounded by the screws

Raspberry Pi + Custom PCB HAT (w/ Si4713) too, but no direct ground connection: Is this a problem? Do I have to make sure, that the ground plane surrounding the Si4713 exciter is directly connected to the grounded case?


Alle the connectors: power supply DC jack, F-type for satellite dish, SO239 share ground with the case. In general: is this advisable?

Thanks for your thoughts![/img]

H
Wed Jan 21, 2015 2:44 pm View user's profile Send private message
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