Today's Message Index:
----------------------
1. 06:22 AM - Bench tester to simulate an alternator (Mickey Coggins)
2. 06:24 AM - Re: 406 ground plane (David Saylor)
3. 07:33 AM - Re: Bench tester to simulate an alternator (Robert L. Nuckolls, III)
4. 08:20 AM - Re: LOM Magneto and Shower of Sparks on Z-18 (Robert L. Nuckolls, III)
5. 09:23 AM - Re: Bench tester to simulate an alternator (Mickey Coggins)
Message 1
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| Subject: | Bench tester to simulate an alternator |
Hi,
Does anyone have a recommendation for a bench tester to see how lifepo4
batteries behave during an overvoltage event? Thinking about buying
various brands of lifepo4 batteries and subjecting them to some overvoltage
to see how they handle it. For science, of course.
Thanks,
Mickey
http://rv8.ch/
Message 2
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| Subject: | Re: 406 ground plane |
OK, 120 it is. Thanks again Aeroelectricians!
On Wed, Oct 25, 2017 at 4:08 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 05:46 PM 10/25/2017, you wrote:
>
> I'm planning to install a new ELT.=C3=82 It comes with a "shark fin" ant
enna
> that incorporates the 406 antenna and the antenna for the internal GPS.
=C3=82
> It has no 121.5 capability.=C3=82 It has a metal base plate, which I tho
ught
> was sufficient for higher frequencies.
>
> However, the installation instructions call for a ground plane of at leas
t
> 120 square inches, and preferably 300 square inches.
>
> Am I missing something?=C3=82 Why would an antenna operating at such hig
h
> frequencies need such a large ground plane?=C3=82 Isn't the rule that th
e
> radius of the ground plane should match the length of the antenna?
>
> --Dave
>
>
> The 1/4 wave ground plane at the lowest frequency of
> interest is 300/406 meters = 0.74M x 39.36 in/M x 0.25
> yields a
>
> *radius of 7.25" * 7.25 (squared) x 3.1416 = 166 square inches . . .
> which
> meets the "120 mininum".
>
>
> Bob . . .
>
Message 3
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| Subject: | Re: Bench tester to simulate an alternator |
At 08:13 AM 10/26/2017, you wrote:
>Hi,
>
>Does anyone have a recommendation for a bench
>tester to see how lifepo4 batteries behave
>during an overvoltage event?=C2 Thinking about
>buying various brands of lifepo4 batteries and
>subjecting them to some overvoltage to see how
>they handle it.=C2 For science, of course.
>
>Thanks,
>Mickey
><http://rv8.ch/>http://rv8.ch/
Sure, a beefy constant V, constant I power supply is the
tool of choice for output currents of 50 amps or so.
Supplies large enough to emulate runaway alternators
are getting harder to find.
I've had one of these on my bench for about 15 years
http://tinyurl.com/yaab7r95
a more modern device might be more to liking
http://tinyurl.com/y82h9vmm
Actually, since you're emulating a runaway
alternator, perhaps tight control over voltage
is unnecessary. You just need a current source
with an open circuit voltage substantially
greater than the battery.
Perhaps a couple of 24v, 20A supplies in parallel
http://tinyurl.com/y7yj2468
You could rig an array of paralleled
light bulbs with switches to serve as an
adjustable, power resistor to give some
control over current to the battery. Alternatively,
you can buy 50w power resistors really cheap
off banggood.com
Here's an exemplar switched resistor load bank I built
for a customer
Emacs!
Resistors are mounted on 1/8 alum plates and force
air cooled. The little collection of parts in the
lower left corner are a zero-to-max variable load
used in combination with switches to 'dial in' what
ever load you wish to run at.
Bob . . .
Message 4
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| Subject: | Re: LOM Magneto and Shower of Sparks on Z-18 |
>I have LOM engine and have a few questions regarding Z-18
>
>What purpose does the filter F526.910-03 serve, is there anything
>else available that will serve the same purpose if it is an essential item?
>
> Those are probably a 'generic' magneto p-lead filter. Leave
> these off until you know you need them. They're easy to add
> if you discover magneto noise in the radios.
>
>The Magneto's that are on my engine do not have a retard terminal as
>shown in the Shower of sparks article, is the LOM magneto different?
>
> Single point magnetos can use vibrator-enhanced
> cranking performance if they are fitted with
> IMPULSE couplers . . . which have the same effect
> as a set of delayed points.
>
>I have the starting vibrator LUN 2231 as described on Z-18, should I
>wire it into the single terminal on the Magneto?
>
> Yes, wire as as shown in Z18.
Bob . . .
Message 5
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| Subject: | Re: Bench tester to simulate an alternator |
> ...
>
> Actually, since you're emulating a runaway
> alternator, perhaps tight control over voltage
> is unnecessary. You just need a current source
> with an open circuit voltage substantially
> greater than the battery.
>
> Perhaps a couple of 24v, 20A supplies in parallel
>
> http://tinyurl.com/y7yj2468
>
>
Great idea - I think I can find plenty of these laying in our scrap server
pile - thanks a bunch!
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