"A test by moving the controller to the tower will probably prove
successful, but it won't determine the source of the problem."... K4SAV
Although it might not pinpoint exactly why, it would at least indicate the
source of the problem is the cable. Since we have several customers
successfully using even longer cables, I think that might be sufficient to
justify cable replacement.
73, Jerry K3BZ
----- Original Message -----
From: "K4SAV" <RadioIR@charter.net>
To: <towertalk@contesting.com>
Sent: Monday, June 11, 2007 10:33 AM
Subject: Re: [TowerTalk] SteppIR cable length
>A test with a larger wire may work or not depending on the source of the
> problem. If the problem is due to IR drop, then the larger wire may fix
> it. If the problem is due to capacitance on the cable, a larger wire
> may make it worse.
>
> A test by moving the controller to the tower will probably prove
> successful, but it won't determine the source of the problem.
>
> The only plausible causes suggested so far, that still remained
> undetermined, is either too much IR drop, or too much stray
> capacitance. Either or both could be contributors. Either scoping the
> power supply voltage or replacing the power supply with one that has
> more current could narrow the source of the problem to being either one
> or both of these contributors. Further test will be required to
> evaluated the degree to which each contributes to the problem.
>
> Jerry, K4SAV
>
> Jim Jarvis wrote:
>
>>Interesting thread.
>>
>>Mike wrote:
>>
>>
>>>I still think it is the length of the cable. Has anyone tried
>>>to measure > current and voltage when under load e.g. when all four
>>>
>>>
>>elements are
>>
>>
>>>being adjusted? I think there is a voltage drop, which is why the
>>>controller malfunctions. Wire has resistance and a lot of wire has
>>>more resistance which has to be overcome.
>>>
>>>Have the Steppir folk actually tried driving a four element with 500
>>>feet plus of wire?
>>>
>>>
>>-0-
>>
>>Joe wrote:
>>If it were me, I would replace the switching supply with a
>>simple analog/linear supply using a 24 volt transformer,
>>a 5 Amp bridge rectifier and 2000 uF of filter capacitance.
>>With no electronic shutdown/foldback one could confirm that
>>the problem is higher than expected peak currents causing
>>the switching supply to shut down.
>>-0-
>>
>>Ron pointed out the size of the cable as an issue.
>>-0--
>>
>>>From my perspective, Mike's question...has SteppIR actually RUN a 500'
>>cable...is key. So is his point about measurement. I'd like to see a
>>scope on the pulse trains, to see what's happening to the stepping pulses.
>>
>>Joe's idea about an alternate power source has merit...but only if
>>SteppIR agrees that it won't void the warranty.
>>
>>Personally, I think Ron is onto the answer. My 3 el was at the end of a
>>200' run of cable, and I went with the heavier gauge wire. I'll bet that
>>an even larger wire size will prove necessary for 500'...or that the
>>capacitance of the longer cable is such that you CAN'T drive the antenna
>>over that length, regardless of IR drop, and that the Mertel's haven't
>>actually tested that long a run.
>>
>>N2EA
>>Jim Jarvis, President
>>The Morse Group, LLC
>>We create high-performance organizations.
>>jimjarvis@themorsegroup.net
>>www.themorsegroup.net
>>
>>
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>>
>>
>>
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>>
>>
>>
>
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