When you current limit the PA you are doing the same thing that happens
when you overdrive a linear amp and cause flat-topping, i.e. the PA is
driven out of its linear range.
That causes spurious products in your transmitted signal.
You would be better off fusing your PA so it can't pull too much
current. Then adjust your drive level so the fuse never blows.
tim ab0wr
On Wed, 14 Mar 2018 15:15:40 -0700
"Walter" <W9KJO@...> wrote:
On Wed, Mar 14, 2018 at 01:28 pm, Jerry Gaffke wrote:
Had never heard of Drok, they have lots of stuff up on Amazon.
Does your Drok allow you to set the max current anywhere from 0
Amps to say 5 Amps?
Sorely needed.
Lots of cheap switchers out there now, but none of them seem to deal
properly with current limiting.
Should be able to set both the regulated voltage and the max
current. If the load sucks too much current, the voltage drops
until the current comes within the set limit.
Any of those switchers could do this for the price of an op-amp and
a pot, maybe an extra $1.
Jerry, KE7ER
?
On Wed, Mar 14, 2018 at 12:47 pm, Walter wrote:
A little more expensive model put out by droke even has a current
limiting feature.
Well, I had not thought about the current limit.
I installed one for the PA voltage that does not have the current
limit feature.? I will change it out to the current limit model and
use the voltage only for the board supply.
Now I just need to figure out how to adjust the current limit.? I
think a resister network to draw current while I adjust it to the
desired current level.? That would be a great safety feature.
Anyone have an idea about what the max safe current for the PA buss
would be??
--
73, W9KJO
Walter
