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The Motorola connector is quite different from the RCA connector. The

ground sleeve is sometimes solid and sometimes slashed, with the ground sleeve sectors "bulged" for solid contact, as seen here. The number of slashes varies.

As pointed out already, the centre conductor of the cable has a tiny

diameter. It's a solid conductor; very little handling of cable and connector will cause a break in the centre conductor within or near the connector.

John

at radio station VE7AOV.

+++++++++

n 2023-09-07 14:23, N2MS wrote:

Wasn't the connector used with auto radios called a Motorola connector? The connector has a larger diameter and the center pin is longer than the RCA "phono" connector?

Mike N2MS

On 09/07/2023 2:27 PM EDT DougVL <k8rftradio@... > wrote:

On Sat, Aug 26, 2023 at 01:32 PM, Ben Cranston wrote:

central pin ¡°is¡± the resonant element

Car radio antennas are a 'high impedance' design, and their co-ax cable is
also Hi-Z.
While 'any antenna' will radiate, some do it FAR better than others.

To more directly answer your original question, you would need a cable
with the proper connector to connect the antenna to the vna. Do you have
one? As I recall, older car radios use a connector like the old RCA phono
plug/jack system. A push-in coaxial plug to fit the car's jack. Get an
extra car antenna with cable from a junkyard, cut off the 'radio' end and
use the cable with the vna.
--
Doug, K8RFT




Screenshot from 2023-09-07 19-44-36

On Thu, Sep 7, 2023 at 11:35 PM, Roger Need wrote:

You can easily build your own SMA female kit which works quite well. Use PCB
board SMA connectors with legs cutoff. Cut the centre pin flush for the open.
For the short use copper disc or foil and then flood with solder. The 50 ohm
load in the picture uses a 50 ohm SMD but use two 100 ohm resistors in
parallel for lower inductance and easier to find.

You can read about the performance of these on this site...

Interesting. But I have tried to solder between SMA connectors legs some time ago and it is hard. Soldering several resistors there is probably inpossible(for me). Putting a lot of solder everywhere seems to be much easier.

On Thu, Sep 7, 2023 at 11:49 PM, Dragan Milivojevic wrote:

Official calibration kits from Hugen have been characterised (huge
thanks to Kurt Poulsen)
with and without the barrel adapter. Use the adapter to turn the male
kit into female.

How is that done? I can only run basic SOLT calibration. I have several of F to M adapters, but now I would like to work and calibrate without adapters.
( At the moment it really doesn't matter, my max frequency is around 100-200MHz).
Thanks for the link, by the way. An interesting idea.

Yes, I forgot that. I am using SMA with V2 Plus4. That is up to 4GHz.

Wasn't the connector used with auto radios called a Motorola connector? The connector has a larger diameter and the center pin is longer than the RCA "phono" connector?

Mike N2MS

Official calibration kits from Hugen have been characterised (huge
thanks to Kurt Poulsen)
with and without the barrel adapter. Use the adapter to turn the male
kit into female.
Alternatively buy some cheap male to female semi rigid coax pigtails
from AliExpress, Ebay etc.
Something like this:

On Thu, Sep 7, 2023 at 12:55 PM, Leif M wrote:

I use VNA often with a short coaxial. I noticed that a male calibration kit
requires an adapter when it is used with a cable. Because cables have a male
connector, too. Ebay has only male calibration kits, at around 20?$€, but
not females ones. SDR kit has some at around 50-80?$€, which I'll buy
someday but not today.

You can easily build your own SMA female kit which works quite well. Use PCB board SMA connectors with legs cutoff. Cut the centre pin flush for the open. For the short use copper disc or foil and then flood with solder. The 50 ohm load in the picture uses a 50 ohm SMD but use two 100 ohm resistors in parallel for lower inductance and easier to find.

You can read about the performance of these on this site...




Roger

You did not mention the specific connector you are using.. Oh and one more thing, what frequency range are you working with?

I use VNA often with a short coaxial. I noticed that a male calibration kit requires an adapter when it is used with a cable. Because cables have a male connector, too. Ebay has only male calibration kits, at around 20?$€, but not females ones. SDR kit has some at around 50-80?$€, which I'll buy someday but not today.

Car radio antennas used a 'Motorola' connector. Motorola invented the car
radio, when the company was still known as ' *Galvin Manufacturing
Corporation* '. It became Motorola in 1930, to signify their car radios.

And the reason why car antenna cables are not 50 ohms... Centre conductor is very thin to keep impedance high (and parallel capacitances low)
DG9BFC sigi

Am 07.09.2023 20:14 schrieb W0LEV <davearea51a@...>:

On Sat, Aug 26, 2023 at 01:32 PM, Ben Cranston wrote:

central pin ¡°is¡± the resonant element

Car radio antennas are a 'high impedance' design, and their co-ax cable is also Hi-Z.
While 'any antenna' will radiate, some do it FAR better than others.

To more directly answer your original question, you would need a cable with the proper connector to connect the antenna to the vna. Do you have one? As I recall, older car radios use a connector like the old RCA phono plug/jack system. A push-in coaxial plug to fit the car's jack. Get an extra car antenna with cable from a junkyard, cut off the 'radio' end and use the cable with the vna.
--
Doug, K8RFT

The simple answer is "you don't".

As pointed out in another email, the AM car antennas are a hi-Z capacitive
probe free space. They are highly capacitive, and measurement in a 50-ohm
system, the NANOVNAs, is senseless.

Dave - W?LEV

On Thu, Sep 7, 2023 at 4:43?AM Michael A. Terrell <
terrell.michael.a@...> wrote:

Old car radios had a tuned RF input, and an RF amplifier. I't's hard to
beat a '63 to late '70's Delco AM car radio. They used a variable
inductor tuning system, with very good tracking between stages. Later
designs eliminated the tuned front end which both lowers sensitivity
and noise rejection. This started with Japanese imports in the early
'70s. A factory radio was hundreds of dollars, but the crap design
import was $20. I serviced hundreds, if not thousands of car radios in
the early to mid '70s. Ford and Chrysler radios were a joke, compared to
Delco. Ford even used Delco radios in their high end Lincolns. Ford
owned Philco, but they also used Bendix and Motorola radios. Chrysler
used pink plastic circuit boards that would melt when you tried to
repair them.

On 8/26/2023 10:22 PM, fbray@... wrote:

At the risk of being slightly OT, there are several reasons that AM

radios are disappearing. One is the EMI problem caused by various vehicle
charging and propulsion systems. The EMI issue is a discussion topic on
forums frequented by public safety and commercial two-way radio techs.

European car makers have dropped AM because it has been supplanted by

DAB and AM stations are shutting down there, leaving little to listen to.
Major US car makers disclaim any intention to abandon AM but we'll have to
wait and see. In major US metro areas some of the AM stations are now
simulcasting on FM so that they don't lose their audience.

Many of us have noted that the AM radios in older cars with traditional

external metal rod antennas work better than the in the glass antennas.

--

*Dave - W?LEV*


--
Dave - W?LEV

Have you tried a known good USB cable? The cables that come with the units
usually are designed for charging, not data transfer.

Dave - W?LEV


On Thu, Sep 7, 2023 at 6:07?AM Brian Stokes <brianstokes@...>
wrote:

Hi Stan

I have tried everything possible to get this unit to connect to a PC. I
did have one computer which I had not connected it to and it wouldn't work
with that one either. I can only conclude that the USB comms chip in the
unit is defective.

The eBay returns window on this unit closed on 1 July. That's how long I
have been messing around with this thing trying to make it work. I have
contacted the seller moralstreasure-006 to see if they will make good.

Thanks

-Brian

--

*Dave - W?LEV*


--
Dave - W?LEV

If I have a bad cable, I cut it in half and discard it. This has also been
the practice at a number of places I've worked, now retired (thank heaven!).

Dave - W?LEV

On Thu, Sep 7, 2023 at 1:12?PM Allen Hill via groups.io <Allenanalog1=
[email protected]> wrote:

Don, excellent pro tip! I've been bitten by forgetting I had a bad cable
and didn't properly discard it.

Thanks!

Allen
KI4QCK

On September 7, 2023, at 8:53 AM, Donald S Brant Jr <dsbrantjr@...>
wrote:

Understand that except for very high-end specialized network analyzer
cables, the flexible cables we buy have to be considered consumables, as
their attachment points and wires will sooner or later begin to degrade
from bending and twisting and will need to be replaced. I just buy cheap
ones and toss them when they start getting noisy, or just break, as they
all do, eventually.

Pro tip: When they do fail, cut off the ends before discarding them; if
you don't somebody will inevitably fish it out and try to use it. "Hey,
look at this nice cable someone threw away. .."
73, Don N2VGU

--

*Dave - W?LEV*


--
Dave - W?LEV

*Finally success!*

Last night I was putzing, once again, with the NanoVNA H4 that was not
measuring SWR but would calibrate.
By swapping out connectors I found a female sma to so239 connector that was
the BAD.
Wow, with another connector I now have beautiful Smith charts, SWRs etc,
that track with the AAA 650 RigExpert.
I am a happy camper now.
Oh my simple mind did not see the simple problem. LOL!

Thanks for all the great ideas and connector sources. I really appreciate
this forum.

Al, KA0VIA

On Thu, Sep 7, 2023 at 7:53?AM Donald S Brant Jr <dsbrantjr@...>
wrote:

Understand that except for very high-end specialized network analyzer
cables, the flexible cables we buy have to be considered consumables, as
their attachment points and wires will sooner or later begin to degrade
from bending and twisting and will need to be replaced. I just buy cheap
ones and toss them when they start getting noisy, or just break, as they
all do, eventually.

Pro tip: When they do fail, cut off the ends before discarding them; if
you don't somebody will inevitably fish it out and try to use it. "Hey,
look at this nice cable someone threw away. .."
73, Don N2VGU

Don, excellent pro tip! I've been bitten by forgetting I had a bad cable and didn't properly discard it.

Thanks!

Allen
KI4QCK

Understand that except for very high-end specialized network analyzer cables, the flexible cables we buy have to be considered consumables, as their attachment points and wires will sooner or later begin to degrade from bending and twisting and will need to be replaced. I just buy cheap ones and toss them when they start getting noisy, or just break, as they all do, eventually.

Pro tip: When they do fail, cut off the ends before discarding them; if you don't somebody will inevitably fish it out and try to use it. "Hey, look at this nice cable someone threw away. .."
73, Don N2VGU

On Sat, Aug 26, 2023 at 01:32 PM, Ben Cranston wrote:

I¡¯ve been totally ¡°blown off the air¡± on 10m by a passing Rivian truck

The body of the vehicle is the ground plane.

This is what I've come to believe. The 'noise' of the various electronics within the truck I believe is the problem. After I came to that conclusion I took the problem to the local uni and was told my thoughts are correct.

AS AN ASIDE, it is a shame that my question somehow became an argument over liberal/conservative politics. The simple fact is Sinclair Broadcast Group owns the VAST MAJORITY of radio stations in America; FURTHER, Sinclair is extremely right wing. Thus the thought of 'eliminating AM radio' as a plot by anyone is absurd. Those wanting to hear either side of the liberal/conservative argument have ample opportunity to be drowned in their particular version of the truth and can easily refuse to hear the other side.

I thank all having tried to answer my question and lament the intrusion of politics. I hope politics will be avoided in the future.

I meant to say traditional AM broadcast band car radio antenna. On FM broadcast band a whip antenna center mounted on a car roof can be a pretty good 1/4 wavelength monopole. The broad consumer marketplace will not accept that. Only radio people are OK with a "real" antenna on a car or truck at lower frequencies. At 450 MHz and above visually subtle effective vehicle antennas can be made, but frequently you see a number of them clustered on a car roof. They have made perfectly good omnidirectional patterns into a parasitic directional antenna. In the US you can see large scale coil loaded whip antennas on vehicles, that appear comical, ego driven or hobby virtue signalling. They may in fact be correct technically. I wonder if they have been software modeled and real-world measured at the frequencies of use, on the variety of vehicle mounting configurations?