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50W power amplifier initial power up.

 

Hello from ZL
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What is the current consumption of the PA when it is in receive mode?
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I would like to set my current limit to just above that for the first power up ie pre key down.
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I don't want to have to release some ¡°Turkish magic smoke¡± should I get things wrong.
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Thanks in advance.
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Chris
 

Hello from SM
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Mine drew 12 mA on receive when powered with 12.0 V.
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My build and test thread pn Mastodon:
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73 DE SA5RJS
 

Hello Chris,

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My inexpensive DVM shows 11mA at the supply voltage of 11.0V and 21mA at 20.3V.

These values may not be very accurate, but the current consumption in the receive mode is very low ¨C the bias current for for two PIN diodes in the receive path, D3 and D5, and the green LED, D11, mostly.

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I hope your amplifier will perform well.

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73, Aki, JO4MTH
 

Hi Guys
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Thank you for the data.
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The two replies are close enough to provide sensible guidance.
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I am going to use a repurposed lipo tool battery. Ie 21 V fresh off the charger and 18.5 V for most of the discharge cycle.
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I will use a couple of diodes in series between 21V and 20V to burn off the excess.
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I will set the bias for 20 V.?
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BR
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Chris
 

21V is within acceptable starting value.? ? Also it will drp soon enough
in use to be under 20.
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--
Allison
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Post online only,?
direct email will go to a bit bucket.
 

Hi Allison
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Thank you for your advice.
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BR
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Chris
 

I suggest? that Assume the amp will draw current? equivalent to? the? A for Watts = 2 x power out expected? (your guess ) then select a fuse 20% higher


That will provide a back up for any current limiting? (or not) it seems not in your power pack.?
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The fuse may or may not? save the mosfets if? something goes south.? But will protect most other components.
These? IRF 510 amps from Hans don't have a reputation for thermal runaway.??

BTW on sport aircraft like sail planes, the? fuse is often put Right on the battery terminal.This can save a lot of tears later - esp for lithium based batteries.
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TEF

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