Re: Can a Crystal be Tested With NANO VNA?
Justin, Either should work for just seeing if the crystal has a resonance near the expected frequency. I've just used channel 0 for S11 measurements, with the coax shield to one side of the crystal and the center conductor to the other side. In that video he's calculating the various parameters of the crystal using through S21 measurements going out of channel 0 and into channel 1. If you have a known good crystal, I'd suggest trying it on that first, so you know you have your settings correct and know what to expect. You may need to adjust your frequency range and vertical range for the readings. -- Rob Campbell KG6HUM On Fri, Sep 8, 2023, 10:44 PM Justin Bowser - KI5GKD < justin.bowser@...> wrote: Thanks, Rob. Do I need to use both channels or just the "primary?"
73,
Justin B.
KI5GKD
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Re: Can a Crystal be Tested With NANO VNA?
Thanks, Rob. Do I need to use both channels or just the "primary?"
73,
Justin B.
KI5GKD
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Re: Can a Crystal be Tested With NANO VNA?
I use mine often to check crystals when I suspect they may be bad. I have some SMA to alligator clip cables which make it easy. You can over the expected frequency range, and you should see a S11 return loss dip and phase shift around the resonant frequency. Also check out this video: -- Rob Campbell KG6HUM On Fri, Sep 8, 2023, 8:54 PM Justin Bowser - KI5GKD < justin.bowser@...> wrote: I'm working on my Heathkit HR-1680 receiver and I have a crystal that I
suspect is bad. Can a NANO VNA be used to test a crystal? If so, how?
Thanks and 73,
Justin B.
KI5GKD
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Can a Crystal be Tested With NANO VNA?
I'm working on my Heathkit HR-1680 receiver and I have a crystal that I suspect is bad. Can a NANO VNA be used to test a crystal? If so, how?
Thanks and 73,
Justin B.
KI5GKD
|
Hello,
I have a NanoVNA-H4, since 1 year, that worked fine until yesterday: I left it running overnight and this morning I found it with the screen frozen and unresponsive. Cycling power it now shows a blank screen, only the backlight is on (and the blue LED inside). The serial port is also no longer recognized by the PC.
The strange thing is that DFU mode works, flashing a new FW succeeds but then it still does not power on properly
I've checked the internal VCC and VDD voltages and they look ok, at 4.23 V and 3.26 V, respectively.
Tried leaving it off a few hours, disconnecting the battery and powering via USB only but to no avail.
Any suggestion about what to check next?
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Re: How do you measure a car antenna?
You can measure them as you would any other lumped component. Typically you¡¯ll wind up with a Z like 2 + 300k j, which is hard to measure.
As to whether the measured Z is meaningful is a whole other story.
What you typically won¡¯t do is try to match them. The external noise dominates, so any ¡°mismatch loss¡± affects signal and noise equally. As noted, they¡¯re a voltage probe, so the system model is a voltage divider with the antenna Z on top of the input Z.
Vin = Efield * length * Zin/(Zin + Zant)
So you want Zin to be big. Getting high R is pretty easy, but there¡¯s a shunt C that actually dominates, so getting C as low as possible is the challenge. Hence low C coax. It¡¯s similar to cables for high Z microphones.
An even more interesting challenge is measuring the amplifier input Z
toggle quoted message
Show quoted text
On Sep 7, 2023, at 12:11 PM, Michael A. Terrell <terrell.michael.a@...> wrote:
?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.
On Thu, Sep 7, 2023 at 2:27?PM 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
|
Re: How do you measure a car antenna?
On Thu, Sep 7, 2023 at 03:11 PM, Michael A. Terrell wrote:
It became Motorola in 1930, to signify their car radios
Interesting! "Motorola connector"? I had no idea! Thanks, larry
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Re: How do you measure a car antenna?
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
|
Re: An affordable female calibration kit, anywhere?
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.
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Re: An affordable female calibration kit, anywhere?
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.
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Re: An affordable female calibration kit, anywhere?
Yes, I forgot that. I am using SMA with V2 Plus4. That is up to 4GHz.
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Re: How do you measure a car antenna?
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
toggle quoted message
Show quoted text
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
|
Re: An affordable female calibration kit, anywhere?
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:
toggle quoted message
Show quoted text
On Thu, 7 Sept 2023 at 21:55, Leif M <leif.michaelsson@...> 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.
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Re: An affordable female calibration kit, anywhere?
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
|
Re: An affordable female calibration kit, anywhere?
You did not mention the specific connector you are using.. Oh and one more thing, what frequency range are you working with?
|
An affordable female calibration kit, anywhere?
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.
|
Re: How do you measure a car antenna?
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.
toggle quoted message
Show quoted text
On Thu, Sep 7, 2023 at 2:27?PM 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
|
Re: How do you measure a car antenna?
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@...>:
toggle quoted message
Show quoted text
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
|
Re: How do you measure a car antenna?
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
|
Re: How do you measure a car antenna?
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
|
Roger Need
Dentron
Michael A. Terrell