Hi,

Connecting a Hantek HT-25 ignition pickup to a Owon HDS2202S mounted
on the dashboard of a vehicle. The HT-25 has a BNC connector.

The firewall has an opening about 4 cm diameter covered with a rubber
plug which can be pierced with a handheld punch. Rather than punch a
hole for the HT-25 BNC connector, I think of connecting a RG-174/U
cable with LEMO 00 connectors using a BNC-LEMO adapter. Then pass the
LEMO connector through the plug. Another adapter will be needed on the
scope.

I'm not familiar with coax usage. Is the arrangement OK?

Thanks, ... P.




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On 31 Aug 2025 15:22:15 -0700, peter@easthope.ca wrote:

Hi,

Connecting a Hantek HT-25 ignition pickup to a Owon HDS2202S mounted
on the dashboard of a vehicle. The HT-25 has a BNC connector.

The firewall has an opening about 4 cm diameter covered with a rubber
plug which can be pierced with a handheld punch. Rather than punch a
hole for the HT-25 BNC connector, I think of connecting a RG-174/U
cable with LEMO 00 connectors using a BNC-LEMO adapter. Then pass the
LEMO connector through the plug. Another adapter will be needed on the >scope.

I'm not familiar with coax usage. Is the arrangement OK?

Thanks, ... P.

You sure it's BNC?

There is a similar HT connector that won't fit BNC hardware.

BNC may be a misapplication.

RL

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

On 31 Aug 2025 15:22:15 -0700, peter@easthope.ca wrote:

Hi,

Connecting a Hantek HT-25 ignition pickup to a Owon HDS2202S mounted
on the dashboard of a vehicle. The HT-25 has a BNC connector.

This one?
<https://hantek.com/products/detail/70> <https://www.amazon.com/Hantek-HT25-Oscilloscope-Capacitance-Diagnostic-tool/dp/B01B17VSH4>

The firewall has an opening about 4 cm diameter covered with a rubber
plug which can be pierced with a handheld punch. Rather than punch a
hole for the HT-25 BNC connector,

Do you really want 2.5 meters of coax cable stored in the engine
compartment?

You could punch a round hole in the rubber plug, but it's easier and
neater to cut and "X" in the rubber. If you change your mind later,
an "X" is easier to reseal than a hole. Your 40mm plug is much larger
than a 14mm BNC plug and therefore does not need an extension cable.
Or, just remove the existing rubber plug and replace it with an
aftermarket grommet: <https://www.amazon.com/Electrical-Retractable-Protecting-Assortment-Automotive/dp/B09CDHLLPG>
Notice the "X". You can cut these grommets from the center to the
edge of the grommet which only requires a hole the diameter of the
coax cable instead of the larger BNC connector diameter.

I think of connecting a RG-174/U
cable with LEMO 00 connectors using a BNC-LEMO adapter. Then pass the
LEMO connector through the plug. Another adapter will be needed on the >scope.

Lemo connectors are expensive. SMA is easier and cheaper. However,
for small diameter coaxial cable, such as RG-174/u, you will probably
need to buy or borrow an SMA crimping too.

I'm not familiar with coax usage. Is the arrangement OK?

Dunno. Let's do the math.
The HT-25 probe is allegedly a 10,000:1 voltage attenuator. Oddly,
the specs say "up to 10,000:1" which suggests that it might be less
than 10,000:1. You might need an additional safety factor. I suggest
5,000:1 instead of 10,000:1.

Automobile ignitions are typically 30,000 to 50,000 volts. That would
mean your oscilloscope input voltage might be 60 to 100 volts. That's acceptable for RG-174/U coaxial cable, which will work to 1500V RMS
(about 2100V peak).

Ok, your cable is safe, but I'm not so sure about the oscilloscope
input. The Owon spec sheet says maximum input voltage is 400VDC+AC,
which I guess(tm) means peak-to-peak volts: <https://files.owon.com.cn/specifications/HDS200.pdf>
In theory, the scope should be able to handle 60 to 100VDC input, but
I would add some additional attenuation to be safe.


--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: ---:- FTN<->UseNet Gate -:--- (3:633/280.2@fidonet)

In article <c44bbk91qdflto66450i3ia5m16crta4j4@4ax.com>,
legg <legg@nospam.magma.ca> wrote:

There is a similar HT connector that won't fit BNC hardware.

HT isn't here.
https://en.wikipedia.org/wiki/List_of_RF_connector_types

Is BNC or HT distinguishable in this photo?
https://easthope.ca/Connectors.jpg

I have a collection of jumpers with the small connectors.
Lemo; correct?

Thx, ... P.


--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

On 02 Sep 2025 13:23:34 -0700, peter@easthope.ca wrote:

In article <c44bbk91qdflto66450i3ia5m16crta4j4@4ax.com>,
legg <legg@nospam.magma.ca> wrote:

There is a similar HT connector that won't fit BNC hardware.

HT isn't here.
https://en.wikipedia.org/wiki/List_of_RF_connector_types

These are the more popular RF connectors. <https://en.wikipedia.org/wiki/RF_connector#/media/File:RF_Connectors_Assortment.jpg>
More, including some less popular RF connectors: <https://www.amphenolrf.com/rf-connectors.html> <https://www.google.com/search?udm=2&q=rf%20connectors>

Is BNC or HT distinguishable in this photo? >https://easthope.ca/Connectors.jpg

I can't tell. Too fuzzy and no contrast.

I have a collection of jumpers with the small connectors.
Lemo; correct?

I have no way to see what you have here. Lemo is a connector
manufacturer and not a specific type of connector. <https://www.lemo.com/en/lemo-connectors>

This is a BNC HT/MHV connector:
<https://www.ebay.com/itm/326167956129> <https://www.google.com/search?udm=2&q=ht%2Fmhv%20coax%20connectors>
The BNC refers to the metal part of the connector. I think HT means
"high tension" but I'm not sure. MHV means "miniature high voltage".
Is this what you have? Such connectors are made for low capacitance
and high voltages. They're NOT made for 50 or 75 ohms.



--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: ---:- FTN<->UseNet Gate -:--- (3:633/280.2@fidonet)

On Tue, 02 Sep 2025 19:50:32 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

Such connectors are made for low capacitance
and high voltages. They're NOT made for 50 or 75 ohms.

If low capacitance, my guess(tm) is that it's 93 ohm RG-62/u coaxial
cable.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: ---:- FTN<->UseNet Gate -:--- (3:633/280.2@fidonet)

On 02 Sep 2025 13:23:34 -0700, peter@easthope.ca wrote:

In article <c44bbk91qdflto66450i3ia5m16crta4j4@4ax.com>,
legg <legg@nospam.magma.ca> wrote:

There is a similar HT connector that won't fit BNC hardware.

HT isn't here.
https://en.wikipedia.org/wiki/List_of_RF_connector_types

Is BNC or HT distinguishable in this photo? >https://easthope.ca/Connectors.jpg

I have a collection of jumpers with the small connectors.
Lemo; correct?

Thx, ... P.

The output of the Hantek HT-25 ignition pickup is not a high voltage
signal, so any kind of shielded signal cable or connector should work.

Bayonet Neil-Concelman (BNC) hardware is used here for convenience
only. Ratings 500Vpk max. Assemblies are prooftested at 1500V.

RL

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

On 31 Aug 2025 15:22:15 -0700, peter@easthope.ca wrote:

Hi,

Connecting a Hantek HT-25 ignition pickup to a Owon HDS2202S mounted
on the dashboard of a vehicle. The HT-25 has a BNC connector.

The firewall has an opening about 4 cm diameter covered with a rubber
plug which can be pierced with a handheld punch. Rather than punch a
hole for the HT-25 BNC connector, I think of connecting a RG-174/U
cable with LEMO 00 connectors using a BNC-LEMO adapter. Then pass the
LEMO connector through the plug. Another adapter will be needed on the >scope.

I'm not familiar with coax usage. Is the arrangement OK?

Thanks, ... P.

The Hantek pick-up has a built-in 10,000:1 attenuator and is designed
for direct connection to a standard 1Meg scope input - so it is
internally padded for the 50ohm cable being supplied.Coax extensions
will have little effect on your practical scope readings.

RL

--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

In article <96jgbk57tpcfcio2t6snijf1vm19dubg51@4ax.com>, legg <legg@nospam.magma.ca> wrote:

The Hantek pick-up has a built-in 10,000:1 attenuator and is designed
for direct connection to a standard 1Meg scope input - so it is
internally padded for the 50ohm cable being supplied.Coax extensions
will have little effect on your practical scope readings.

Thanks, ... P.


--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

In article <h7afbkl8ug26mvphahsqlsa6rkpuclugvk@4ax.com>, Jeff Liebermann <jeffl@cruzio.com> wrote:

Lemo is a connector manufacturer and not a specific type of connector. <https://www.lemo.com/en/lemo-connectors>

With reading glasses, the small connectors in my photo are marked
LEMO
F 00 250
.. Similar to the FFA 00 250.

https://www.lemo.com/int_en/solutions/specialties/00-nim-camac/ffa-00-250-ctac31.html

https://web.lemo.com/img/resources/catalog/ROW/UK_English/00and01Coaxial_en.pdf pages 6 & 7

Thx, ... P.



--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

In article <nphbbk9k2q4u562nt7kenbb7dmrmcsv68d@4ax.com>, Jeff Liebermann <jeffl@cruzio.com> wrote:

Do you really want 2.5 meters of coax cable stored in the engine
compartment?

Ignition connection to firewall will take at least a meter. Surplus length
is easily coiled and zip tied out of the way.

You could punch a round hole in the rubber plug, but it's easier and
neater to cut and "X" in the rubber. If you change your mind later,
an "X" is easier to reseal than a hole.

Good idea. Might do that. Thanks.

Or, just remove the existing rubber plug and replace it with an
aftermarket grommet: <https://www.amazon.com/Electrical-Retractable-Protecting-Assortment-Automotive/dp/B09CDHLLPG>
Notice the "X". You can cut these grommets from the center to the
edge of the grommet which only requires a hole the diameter of the
coax cable instead of the larger BNC connector diameter.

In this instance the grommet is oval with diameeter at one end bigger
than the other. Unfortunately a round grommet won't work. Don't
recall another opening in the firewall but will check again.

Thx, ... P.


--- MBSE BBS v1.1.2 (Linux-x86_64)
* Origin: A noiseless patient Spider (3:633/280.2@fidonet)

In article <c44bbk91qdflto66450i3ia5m16crta4j4@4ax.com>, legg <legg@nospam.magma.ca> wrote:

You sure it's BNC?

No. There are many coaxial connectors. https://en.wikipedia.org/wiki/List_of_RF_connector_types
My knowledge is minimal and some statements here are speculative.
Corrections welcome.

I've posted a photo of four connectors. https://easthope.ca/CoaxialConnectors.jpg
The photo isn't high resolution but suffices to show salient features.

Left to right in the photo.

(1) BNC to Lemo adapter with a Lemo patch cable connected. Connects
to the Owon HDS2202S oscilloscope BNC connector.

(2) BNC to RCA with patch cable connected. Connects to the scope.

(3) BNC on the Hantek HT-25 automotive ignition pickup. Connects to
the scope.

(4) ?? on a patch cable marked ITT WIRE & CABLE DIV. RG-59/u COAXIAL
CABLE. The protrusion of the white insulator prevents connection to
the scope.

There is a similar HT connector that won't fit BNC hardware.

(4) appears to be an instance. I don't see it in the Wikipedia list
and don't have a name for it.

Now fairly certain I can connect the Owon well enough to see
significant automotive ignition problems.

Thanks, ... P.



--- PyGate Linux v1.5
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 04 Sep 2025 08:07:38 -0700, peter@easthope.ca wrote:

In article <nphbbk9k2q4u562nt7kenbb7dmrmcsv68d@4ax.com>, Jeff Liebermann <jeffl@cruzio.com> wrote:

Do you really want 2.5 meters of coax cable stored in the engine
compartment?

Ignition connection to firewall will take at least a meter. Surplus length >is easily coiled and zip tied out of the way.

You could punch a round hole in the rubber plug, but it's easier and
neater to cut and "X" in the rubber. If you change your mind later,
an "X" is easier to reseal than a hole.

Good idea. Might do that. Thanks.

Or, just remove the existing rubber plug and replace it with an
aftermarket grommet:
<https://www.amazon.com/Electrical-Retractable-Protecting-Assortment-Automotive/dp/B09CDHLLPG>
Notice the "X". You can cut these grommets from the center to the
edge of the grommet which only requires a hole the diameter of the
coax cable instead of the larger BNC connector diameter.

In this instance the grommet is oval with diameeter at one end bigger
than the other. Unfortunately a round grommet won't work. Don't
recall another opening in the firewall but will check again.

This should be easy. Measure the circumference of the oval hole. I
suggest using a piece of copper wire. Grommets are specified by the
equivalent diameter of the round hole that it will fit. Divide the
measured oval hole circumference by 3.14 to obtain the diameter. Look
for a grommet with the same diameter. If it's made from fairly
flexible, the grommet should deform to the desired oval shape.

If the grommet size is too large for commodity grommets, try using a
continuous grommet strip: <https://www.google.com/search?udm=2&q=continuous%20grommet%20strip>
To make it water resistant, you might need to add a plastic or PVC
cut-out which is slightly smaller than the oval hole.

Also see "grommet edging" <https://www.iqsdirectory.com/articles/rubber-molding/grommet-edging.html>



--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272 AE6KS 831-336-2558


--- PyGate Linux v1.5
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)