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What the VNA will not do is tell if a given crystal will oscillate, cleanly and on frequency, in a particular circuit, which is what the OP wants.
73, Don N2VGU

Hi Tom;

You might try reflashing the firmware and also the bootloader. Both may have been corrupted when the battery died, and it sounds like the bootloader MB ay still be.

--
73

Gary, N3GO

The basic go no go test as described is fine. However if you want to accurately determine the crystal parameters you will need more work. For HF crystals a good test jig to avoid strays is useful. Also at resonance the crystal is a series tuned circuit with very very low loss resistance R. This is not a good match to the nano vna which is 50 ohms. There will be both phase and frequency shifts as well. Unraveling all these for the crystal parameters is a challenge.

Rob,

Thanks for the info. I've got a few crystals laying around and I'm basically just looking for a go/no-go on the crystal as it appears dead in circuit. I'll watch the video in the morning, too tired to concentrate on it right now!

73,

Justin B.
KI5GKD

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

Thanks, Rob. Do I need to use both channels or just the "primary?"

73,

Justin B.
KI5GKD

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

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?

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

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

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.