You might check out the new SD-100 SteppIR controller. It is standard
equipment on the DB-series antennas, and supposedly has a much more robust
output circuit arrangement.
The driver board can even be located 100s of feet from the controller
itself, as in up/on the tower.
Bob, W5LT
-----Original Message-----
From: jimlux [mailto:jimlux@earthlink.net]
Sent: Monday, July 13, 2009 10:16 PM
To: Dan Zimmerman N3OX
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] STEPPIR QUESTION
Dan Zimmerman N3OX wrote:
>> Is there a way to build an external box with something like
opto-isolators
>>
> to better isolate the driver chips from getting nailed so easily?
>
>
> Well, you need to build something that can source as much current as the
> driver chips.
>
> Wonder what happens if you replace each output with a thousand-volt MOSFET
?
>
Circuits made to take big transients would do something very much like
that.. They use a fairly decent FET or IGBT with 100V or more. Then a
fast clamp on the output (like a back to back thyristor/DIAC) to limit
the voltage (zeners might work, but because their voltage stays high,
they dissipate more power).. Finally, a series transient suppressor (a
LC circuit of some sort) to limit the di/dt, and then a vacuum gap
across the whole thing where it goes to the outside world.
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