It would be complicated to do that, and I'm not sure the opto-isolators
could be protected.
SteppIR has a new controller with optional remote driver board with optional
surge protection. It uses a surge-detection circuit and relays to disconnect
the control lines from the driver chips. I have some reservations about the
design of the lightning protection, and SteppIR doesn't guarantee that it
provides 100% protection.
73, Dick WC1M
> -----Original Message-----
> From: N2TK [mailto:tony.kaz@verizon.net]
> Sent: Sunday, July 12, 2009 7:24 PM
> To: 'Dick Green WC1M'; 'Bob Gibson'; TowerTalk@contesting.com
> Subject: RE: [TowerTalk] STEPPIR QUESTION
>
> 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? Maybe
add
> MOV's to the opto-isolators? The breakdown voltage of the opto-isolators
> would seem to give some protection to the controller.
> Presently I use a 25 pin LPT switch box to ground the controller line to
the
> antenna during the summer months when I am not operating.
>
> N2TK, Tony
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Dick Green WC1M
> Sent: Sunday, July 12, 2009 1:08 PM
> To: 'Bob Gibson'; TowerTalk@contesting.com
> Subject: Re: [TowerTalk] STEPPIR QUESTION
>
> I have a 3-stack of 4-el SteppIRs and lost all three controllers in a
> lightning hit two years ago. All the driver chips were fried. The RS-232
> interfaces mounted on the control boards were destroyed as well.
> Unfortunately, the RS-232 provided a path to my computer, which was
killed,
> along with damage to every device connected to the computer via RS-232.
> Total cost was around $10,000 (including some stereo equipment not
connected
> to the shack), mostly covered by insurance.
>
> The driver chips are surface-mount, so not very easy to remove and replace
> unless you're familiar with SMD. I got three refurbished controller boards
> from SteppIR instead. This fixed the problem, or so I thought. The
antennas
> worked OK for about eight months, then the CPUs started acting up and I
had
> to replace them. Evidently, there was subtle damage that caused the CPUs
to
> slowly deteriorate. The symptom was occasional high SWR, which got more
and
> more frequent. Believe me, that was a difficult problem to troubleshoot!
> Fortunately, the CPU chips are inexpensive and easy to replace. I've had
no
> problems with the controllers since.
>
> After much thought, I've concluded that lightning suppressors do not
provide
> adequate protection for the SteppIR control box. First, the typical ICE or
> Polyphaser unit has MOVs that trigger at 65V-80V. The SteppIR driver chips
> are attached directly to the control wires, which means the voltage on the
> pins can get as high as 65V-80V before the MOVs shunt the surge. That's
way
> too high for these delicate chips. Many a SteppIR owner has discovered
that
> the chips are highly vulnerable to shorts, and I think they're just as
> sensitive to over voltage. MOV-based suppressors for the ham market are
> designed for much less delicate equipment, such as the output from a rotor
> controller, antenna switches, etc., which can take considerable voltage.
In
> the strike described above, I also lost FET driver transistors in two
Green
> Heron rotor controllers, further evidence that MOVs don't do a very good
job
> protecting certain semiconductors. Fortunately, the FETs were cheap and
easy
> to replace.
>
> K7IR, SteppIR's owner-designer, told me that a 45V MOV would be just about
> right for the driver chips. That's because there's a bit of a spike on the
> 33V signal. I assumed the ICE protectors provided by SteppIR have had
their
> MOVs reduced to that value, but another owner told me they were stock. Not
> sure if that's still true. I use K5FD suppressor boards and had Jim
replace
> the stock MOVs with 45V units. But there's something like a 10% overshoot
in
> the MOV rating, so I think the voltage can get higher than 45V. I don't
> recall the specs on the driver chips, but suspect even a 45V MOV will let
> the voltage rise too much.
>
> For that reason, I don't rely on the suppressors to protect the
controllers.
> When not in use during the summer, or whenever we leave the house
overnight,
> I disconnect the SteppIR control cables and power supplies.
>
> I wouldn't be so quick to sell your SteppIR. Depending on your needs, it's
a
> fine antenna and a great compromise if you can't put up monobanders for
the
> high bands. My 3-stack really rocks. You just have to take some
precautions.
>
> 73, Dick WC1M
>
>
>
> > -----Original Message-----
> > From: Bob Gibson [mailto:w5rg@yahoo.com]
> > Sent: Sunday, July 12, 2009 9:44 AM
> > To: TowerTalk@contesting.com
> > Subject: [TowerTalk] STEPPIR QUESTION
> >
> >
> >
> >
> >
> > Hi group...We had a bad Storm move in the area a few days ago and I may
> have
> > been hit by lightning..we lost a TV..also now my 4 ele Steppir is not
> > working..I think it is in the box itself..I have the antenna ran into a
> > protection box from Steppir and the control box was grounded...When I
turn
> on
> > the unit all looks fine..when I change bands..the box goes out and the
> light
> > blink red and turns off!..Any ideas? This antenna will be for sale when
I
> get
> > it working again..pick up in North Fl...$1400...Thanks Bob
> >
>
>
> _______________________________________________
>
>
>
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