[TowerTalk] SteppIR problem-update from the front lines

[Bob Maser]

One would have thought that SteppIR would have stepped up and solved the 
problem by now.  Maybe if this thread would have been put on the SteppIR 
reflector, they might have gotten involved.

Bob W6TR
----- Original Message ----- 
From: "VR2BrettGraham" <vr2bg at harts.org.hk>
To: <towertalk at contesting.com>
Sent: Monday, June 18, 2007 11:07 PM
Subject: Re: [TowerTalk] SteppIR problem-update from the front lines


> This thread has been interesting to watch, though a bit
> frustrating waiting for everyone to catch up.
>
> K4SAV said:
>
>>My best guess as to the cause of this is that you are right up to the
>>limit of what the system can do. The long cable length combined with the
>>excessive current pulse presented to the power supply by the controller
>>is causing the supply to drop too low.  Remember the power supply
>>voltage transient is present whether the cable is connected to the
>>antenna or not, so a large part of this transient problem is not due to
>>load, but due to some "feature" in the controller.
>
> I see about a 6 volt drop (without or without a motor
> connected) from the power supply when power cycling the
> controller for my SteppIR dipole.  This drop is the same
> with or without the motor connected.
>
> I also see 1.2 volt peak-to-peak spikes with the controller
> off & 1.3 volt peak-to-peak spikes with the controller on
> top of the 25.whatever volts coming from the supply at
> 156 kc.  The power supply by itself is very clean.
>
> The power supply is a Franmar F19603N, rated for 24 volts
> at 2.7 amps.  Franmar's web site looks to have not been
> updated for four years & apparently no longer offers the
> F19603N, as could not find it listed in product section.
> There is a paper sticker on the case that reads "CODE
> #25.2V" so presumably the output voltage is higher than
> the permanent marking on the product.
>
> You can find a spec sheet for the F19603N at:
>
> http://www.craftec.no/productPDF/archive/Switchbox_F1960.pdf
>
> Where one can read that it has short circuit protection,
> but is rated to supply only 2.7 amps max, with dymanic
> load voltage regulation of +/- 5% going from half to full
> load or vice versa.
>
> 5% of 25.2 volts is 23.94 volts, so the power supply is
> acting like it has a load on it well in excess of its rating
> (at least momentarily).
>
> Presumably, the only difference between the two power
> supplies SteppIR offers is output voltage, so if there is
> a moment where the supply is asked to source current
> in excess of that, the output almost certainly is going
> to wilt.
>
> Perhaps AH6FC can share with us the markings on the
> supply(s) he's received, as perhaps there has been a
> change since 2003 (when I bought my dipole).
>
> There is a presumption that the supply included with
> the product would be suited for the task, but it appears
> that the incoming voltage is being pulled below what
> the LM2596 inside likes (that is where the 156 kc crud
> is coming from - the controller design has _no_ regard for
> EMC at all) & this then causes the CPU to go on
> walkabout & not come back.
>
> But having been told so many times I do not know
> anything about anything, I'm obviously wrong about
> this one, too.
>
> 73, VR2BrettGraham
> http://home.pacific.net.hk/~vr2bg/steppir
>
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