Today's Message Index:
----------------------
1. 05:39 AM - Re: Relays (Larry Rosen)
2. 06:39 AM - Re: Relays (user9253)
3. 09:23 AM - Re: Re: Handheld transceiver alternate antenna (Hariharan Gopalan)
4. 03:25 PM - Re: Relays (Larry Rosen)
5. 03:48 PM - Re: Re: Handheld transceiver alternate antenna (Bill Maxwell)
6. 08:32 PM - Re: Relays (LarryRosen)
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Relays can also stick for mechanical reasons unrelated to contact current or to
coil current. Many relays are made with a thin film of non-magnetic material
between the coil core and the armature to prevent them from sticking together
due to residual magnetism. If that thin film is missing or damaged, the relay
can stick closed.
At work a machine operator complained that the equipment started up all by itself.
The equipment was a large mixing tank powered by a 5 HP three phase motor.
The operator pushed the stop button and the run-light went out. Later the
operator noticed that the mixer was running again. He called an electrician
who confirmed that the motor started running all by itself. (Even reliable witnesses
make mistakes.) I got involved and found that the start-stop buttons
send signals to a PLC (Programmable Logic Controller). And the PLC controls
the run indicator light and an AC contactor. The PLC worked fine. When the stop
button was pushed, the run indicator light went out and the PLC opened the
contactor coil circuit. But the contactor did not open. So it turns out that
the motor did not start up all by itself. It never stopped running when the
stop button was pushed. I replaced the contactor and that fixed the problem.
I examined the contractor on the workbench but could not find any mechanical
problem with it. My conclusion was that the contactor was sticking closed due
to either residual magnetism or due to atmospheric pressure (like when two oily
flat surfaces can be hard to separate). The contactor did have two large
mating surfaces that fit perfectly together. The moral of the story is, expect
the unexpected and verify what other tell you.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=440037#440037
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Subject: | Re: Handheld transceiver alternate antenna |
Found this article in kitplanes archive which describes a $2 antenna
diplexer.
*http://tinyurl.com/nz6q8qb <http://tinyurl.com/nz6q8qb>*
On Wed, Feb 25, 2015 at 9:30 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 16:34 2015-02-25, you wrote:
>
> It could be made to work Ken but it is more complicated than necessary. It
> also needs a 12 volt supply and utilises SMA connectors. I suggest you look
> for a much simpler mechanical switch type. They are commonly available
> from ham radio suppliers and usually are fitted with SO-239 connectors.
> Connection is selected by simply turning a knob or flicking a switch.
> Better reliability.
>
>
> Most COTS antenna switches are designed
> to select from two or more antennas to a
> single transceiver/receiver . . . there
> are no concerns for leaving "the alternate
> transceiver" unterminated.
>
> It turns out that ICOM produces a convenient little, optionally
> panel-mounted device for exactly what you need, under the name Antenna
> Switchbox, P/N IC-ANT-SB, which can be had for $64 from Aircraft Spruce
> including the BNC-terminate interconnect cable for your handheld.
>
> Yes, I purchased one about a dozen years ago
> and dissected it.
>
> http://tinyurl.com/nn2sysd
>
> http://tinyurl.com/pp6tzgv
>
> . . . yes, it performs as advertised but not
> very sanitary with respect to managing a
> transmission line. Another concern for me was
> a kind flimsy, normally-closed contact on the jack that
> was supposed provide center-conductor integrity
> through the adapter. Finally, the ICOM product
> was pretty over-sized to the task. I fiddled with
> a DIY version . . .
>
> http://tinyurl.com/kluld58
>
> . . . that didn't put as bit a 'lump' in the
> transmission line's RF profile. It was a lot less
> demanding of panel real estate. But it still
> offered lackluster robustness due to quality
> of the n.c. audio jack being pressed into
> service as a coax connector.
>
> I toyed with the idea of offering a crew
> accessible antenna switch that would terminate
> the OFF transceiver line in a little dummy load.
> I think I offered to bring one into being as an
> AEC product if I could get a commitment for
> purchase of some small quantity of units . . .
> I think it was ten.
>
> That didn't rise off the ground either. SSSsoooooo . . .
> a completely independent antenna or a DIY 'patch
> cable' of some arrangement are the elegant
> choices.
>
> Bob . . .
>
> *
>
>
> *
>
>
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Message 5
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Subject: | Re: Handheld transceiver alternate antenna |
Strictly speaking, I don't think it qualifies as a diplexer but it
should certainly work.
On 31/03/2015 3:22 AM, Hariharan Gopalan wrote:
> Found this article in kitplanes archive which describes a $2 antenna
> diplexer.
>
> *http://tinyurl.com/nz6q8qb*
> *
> *
>
>
> On Wed, Feb 25, 2015 at 9:30 PM, Robert L. Nuckolls, III
> <nuckolls.bob@aeroelectric.com <mailto:nuckolls.bob@aeroelectric.com>>
> wrote:
>
> At 16:34 2015-02-25, you wrote:
>> It could be made to work Ken but it is more complicated than
>> necessary. It also needs a 12 volt supply and utilises SMA
>> connectors. I suggest you look for a much simpler mechanical
>> switch type. They are commonly available from ham radio suppliers
>> and usually are fitted with SO-239 connectors. Connection is
>> selected by simply turning a knob or flicking a switch. Better
>> reliability.
>
> Most COTS antenna switches are designed
> to select from two or more antennas to a
> single transceiver/receiver . . . there
> are no concerns for leaving "the alternate
> transceiver" unterminated.
>
> It turns out that ICOM produces a convenient little, optionally
> panel-mounted device for exactly what you need, under the name Antenna
> Switchbox, P/N IC-ANT-SB, which can be had for $64 from Aircraft
> Spruce
> including the BNC-terminate interconnect cable for your handheld.
>
> Yes, I purchased one about a dozen years ago
> and dissected it.
>
> http://tinyurl.com/nn2sysd <http://tinyurl.com/nn2sysd>
>
> http://tinyurl.com/pp6tzgv <http://tinyurl.com/pp6tzgv>
>
> . . . yes, it performs as advertised but not
> very sanitary with respect to managing a
> transmission line. Another concern for me was
> a kind flimsy, normally-closed contact on the jack that
> was supposed provide center-conductor integrity
> through the adapter. Finally, the ICOM product
> was pretty over-sized to the task. I fiddled with
> a DIY version . . .
>
> http://tinyurl.com/kluld58 <http://tinyurl.com/kluld58>
>
> . . . that didn't put as bit a 'lump' in the
> transmission line's RF profile. It was a lot less
> demanding of panel real estate. But it still
> offered lackluster robustness due to quality
> of the n.c. audio jack being pressed into
> service as a coax connector.
>
> I toyed with the idea of offering a crew
> accessible antenna switch that would terminate
> the OFF transceiver line in a little dummy load.
> I think I offered to bring one into being as an
> AEC product if I could get a commitment for
> purchase of some small quantity of units . . .
> I think it was ten.
>
> That didn't rise off the ground either. SSSsoooooo . . .
> a completely independent antenna or a DIY 'patch
> cable' of some arrangement are the elegant
> choices.
>
> Bob . . .
>
> *
>
> ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
>
> *
>
>
> *
>
>
> *
Message 6
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I will try one more time. Not sure why my message got through without any text.
Putting the signal relay into a backshell seems like an interesting project I would
like to try.
Are there any d-sub backshells that are better suited to stuffing the relay into?
I have looked some electrical catalogs for a mounting bracket like you describe.
I take it it is a roll your own.
And finally would you solder wire to the relay and use pins into the d-sub?
I will post pictures when I get it done.
Larry
--------
Larry Rosen
#40356
N205EN (reserved)
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