When replacing a screen on my tablet, the instructions said that using a
heat gun would soften that double-sided adhesive and make it so you could
carefully separate it.
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On Sun, Sep 5, 2021, 9:56 AM Stephen Laurence <Gaslaurence@...> wrote: If you use a wallpaper scraper or maybe a ¡°bluntish¡± Stanley knife to
gently prise the old screen up, you should not damage components on the
other side of the board.
Before finally committing to lifting it with possible damage to the
flexible connector which needs unsoldering from the board, you should check
that the ribbon on the new board is identical.
Steve L
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Joe,
I believe you are building the pi network for an RF amplifier. Once you have measured and installed the coil and capacitors in the RF Amplifier you can tweak the settings to compensate for stray capacitance and inductance by measuring the 50 ohm output impedance in the amplifier by simulating the RF Plate resistance.
BEFORE YOU DO THIS MEASUREMENT VERIFY THE AMPLIFIER IS POWERED DOWN AND PLACE A SHORT ACROSS THE POWER FILTER CAPACITORS TO DISCHARGE THE CAPACITORS!
- Place the RF Tube in it's socket. This will simulate the tube capacitance.
The ARRL handbook gives the following approximation formula for calculating the load
resistance of a vacuum tube power amplifier:
Vp
Rl = ----
KIp
where K is 1.5 for class AB, 1.57 for class B, and 2 for class C.
Calculate and install a non-inductive resistor from tube late to ground to simulate the Plate load.
- Install the NanoVNA on the RF Output connector
- Set the PI Network Capacitors and Coil for each band and adjust the capacitors (and coil tap if necessary) to get the output impedance close to 50 +j0 ohms.
The plate formula is an approximation but these measurements will get you into the ballpark.
- Remove the resistor before operating the amplifier.
BEFORE YOU DO THIS MEASUREMENT VERIFY THE AMPLIFIER IS POWERED DOWN AND PLACE A SHORT ACROSS THE POWER FILTER CAPACITORS TO DISCHARGE THE CAPACITORS!
I used to repair and install Marine MF (2 to 4 Mhz) radios on boats when I was in college 45 years ago. I had to adjust the output series coil to resonate the 20 foot whip antenna. I was I had the NanoVNA back in those days!
73 Mike N2MS
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On 09/05/2021 2:25 PM Joe WB9SBD <nss@...> wrote:
Thanks all I was doing it right.
This group is awesome!
Joe
On 9/5/2021 12:31 PM, Andrew Kurtz via groups.io wrote:
On Sep 5, 2021, at 1:18 PM, Joe WB9SBD <nss@...> wrote:
I have down right now how to accurately measure a coils inductance.
Now what is the most accurate way to measure a capacitor?
Joe
I measured capacitors exactly the same way as inductors: S11 (reflection) with one side of CH0 attached to one end and the other side to the other end. I even found C values more stable as frequency changes, which I have convinced myself is to be expected because parasitic L in a capacitor is weaker than parasitic C in an inductor, and also the effect of it (being combined in series rather than in parallel) has a much smaller impact.
Andy
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Thanks all I was doing it right.
This group is awesome!
Joe
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On 9/5/2021 12:31 PM, Andrew Kurtz via groups.io wrote:
On Sep 5, 2021, at 1:18 PM, Joe WB9SBD <nss@...> wrote:
I have down right now how to accurately measure a coils inductance.
Now what is the most accurate way to measure a capacitor?
Joe
I measured capacitors exactly the same way as inductors: S11 (reflection) with one side of CH0 attached to one end and the other side to the other end. I even found C values more stable as frequency changes, which I have convinced myself is to be expected because parasitic L in a capacitor is weaker than parasitic C in an inductor, and also the effect of it (being combined in series rather than in parallel) has a much smaller impact.
Andy
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On Sun, Sep 5, 2021 at 10:31 AM, Andrew Kurtz wrote: I even found C values more stable as frequency changes, which I have convinced
myself is to be expected because parasitic L in a capacitor is weaker than
parasitic C in an inductor, and also the effect of it (being combined in
series rather than in parallel) has a much smaller impact.
It all depends... If the capacitor is a small value lead length has a considerable effect on the measurement. See graph below of a ceramic cap marked as 10 pF. Measuring caps was discussed in the link I posted above and many interesting comments were made by knowledgeable members of this group on this subject. I think you will find it well worth reading. Roger
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On Sep 5, 2021, at 1:18 PM, Joe WB9SBD <nss@...> wrote:
I have down right now how to accurately measure a coils inductance.
Now what is the most accurate way to measure a capacitor?
Joe
I measured capacitors exactly the same way as inductors: S11 (reflection) with one side of CH0 attached to one end and the other side to the other end. I even found C values more stable as frequency changes, which I have convinced myself is to be expected because parasitic L in a capacitor is weaker than parasitic C in an inductor, and also the effect of it (being combined in series rather than in parallel) has a much smaller impact. Andy
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On Sun, Sep 5, 2021 at 10:18 AM, Joe WB9SBD wrote:
I have down right now how to accurately measure a coils inductance.
Now what is the most accurate way to measure a capacitor?
An extensive discussion of measurement methods, pitfalls and how to test capacitors and inductors in a previous post last February. /g/nanovna-users/topic/80744049#20809Also see how to's of the wiki - /g/nanovna-users/wiki#How-to27sRoger
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I have down right now how to accurately measure a coils inductance.
Now what is the most accurate way to measure a capacitor?
Joe
|
If you use a wallpaper scraper or maybe a ¡°bluntish¡± Stanley knife to gently prise the old screen up, you should not damage components on the other side of the board.
Before finally committing to lifting it with possible damage to the flexible connector which needs unsoldering from the board, you should check that the ribbon on the new board is identical.
Steve L
|
Larry:
Todah Rabah.
May you and all our colleagues have a sweet and healthy year!
73
Ray
From the home of
Prof. Emeritus Raymond (Reuven) Boxman
School of Electrical Engineering
Tel Aviv University
Cell: ???? +972 544 634 217
CEO Clear Wave Ltd.? ?????????????
Scientific Writing Courses: ???????
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Larry Rothman Sent: ????? 05 ?????? 2021 16:01 To: [email protected]Subject: Re: [nanovna-users] nanoVNA developers Ray,? Shana Tova and Gmar Hatima Tova. Be well! ... Larry Rothman On Fri., 3 Sep. 2021 at 4:57 a.m., Ray<boxman@...> wrote:
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Ray,?
Shana Tova and Gmar Hatima Tova.
Be well!
... Larry Rothman
On Fri., 3 Sep. 2021 at 4:57 a.m., Ray<boxman@...> wrote:
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Re: ST Driver goes thru install but does not connect or show up in device manager
#firmware
Hey Doug:
I had many driver problems with my nanoVNA v2. I could not get it to work with STM or Cypress drivers. What finally worked for me at least partially was to delete all com and usb drivers, reboot, turn on the nanoVNA, and let windows 10 install the generic Microsoft USB driver. This allows me to run nanoVNA View and nano VNA App (but not nanoVNA Saver).
73
Ray 4X1RB
From the home of
Prof. Emeritus Raymond (Reuven) Boxman
School of Electrical Engineering
Tel Aviv University
Cell: ???? +972 544 634 217
CEO Clear Wave Ltd.? ?????????????
Scientific Writing Courses: ???????
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of DougVL Sent: ????? 05 ?????? 2021 03:38 To: [email protected]Subject: Re: [nanovna-users] ST Driver goes thru install but does not connect or show up in device manager #firmware Yes, I made sure a driver was installed. And I installed both en.stsw-stm32080_v3.0.6 and en.stm32cubeprg-win64_v2-8-0_v2.8.0 Neither of those programs finds the Nano, but Device Manager shows that the correct COM port exists. My system did work a several weeks ago, but recently I wanted to try a new firmware, and my DFUseDemo no longer worked. So I tried the newer version (listed above) and that didn't work either. The STM site also recommended using their Cube program (also listed above) , but that also fails to find the Nano, although the COM port is OK. And I think I tried the NanoVNA-APP, and that failed also. -- Doug, K8RFT
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Thank you !
I will check this and investigate further in the next days.
Best regards, 73
Rainer, DK2ZR
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Re: Sweep and stimulus timing
My H4 measure (use 1-10MHz sweep for better grab):
Signal generate non stop (no pauses between points)
1 image 5.59MHz point measure
2 image next point 5.6125MHz
No visible switch on measure (just measured frequency change on display)
On screenshot top visible all measured oscilloscopre 28M points
PS original edy555 firmware disable output for set new frequency on si5351 generator, and wait more time for generation stable
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Re: ST Driver goes thru install but does not connect or show up in device manager
#firmware
my DFUSEDemo worked a couple ofweeks ago but did not work yesterday.
I looked at the Device Manager and the Bootlaoder drive came up. I had to reinstall the DFU driver.
Mike N2MS
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On 09/04/2021 8:37 PM DougVL <k8rftradio@...> wrote:
Yes, I made sure a driver was installed.
And I installed both
en.stsw-stm32080_v3.0.6
and
en.stm32cubeprg-win64_v2-8-0_v2.8.0
Neither of those programs finds the Nano, but Device Manager shows that the correct COM port exists.
My system did work a several weeks ago, but recently I wanted to try a new firmware, and my DFUseDemo no longer worked. So I tried the newer version (listed above) and that didn't work either. The STM site also recommended using their Cube program (also listed above) , but that also fails to find the Nano, although the COM port is OK.
And I think I tried the NanoVNA-APP, and that failed also.
--
Doug, K8RFT
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Re: ST Driver goes thru install but does not connect or show up in device manager
#firmware
Yes, I made sure a driver was installed.
And I installed both
en.stsw-stm32080_v3.0.6
and
en.stm32cubeprg-win64_v2-8-0_v2.8.0
Neither of those programs finds the Nano, but Device Manager shows that the correct COM port exists.
My system did work a several weeks ago, but recently I wanted to try a new firmware, and my DFUseDemo no longer worked. So I tried the newer version (listed above) and that didn't work either. The STM site also recommended using their Cube program (also listed above) , but that also fails to find the Nano, although the COM port is OK.
And I think I tried the NanoVNA-APP, and that failed also.
--
Doug, K8RFT
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Re: Sweep and stimulus timing
On 9/4/21 12:07 PM, Kent AA6P wrote: Thanks for running the test and posting the three images. Were you using a NanoVNA-H with 101 data points? I was not able to correlate the images with the operation of my two devices as I understand them. Yes, NanoVNA-H, 101 data points.
In listening to the signals on a radio receiver, my NanoVNA-H4 appears to do a sweep in slightly less than 1 second. With 401 data points, that would allow a little less than 2.5 milliseconds per data point.
My NanoVNA-H appears to do a sweep of 101 data points in roughly 300 milliseconds. That would allow approximately 3 milliseconds for each data point.
You're right.. sweep3 shows a sweep interval is about 1 second (2 div at 500 ms/div), of which half seems to be "dead time". Sweep 1 and 2, show a pretty consistent pulsing with the pulses being ~80 ms long, which with 101 points would be an 8 second sweep. Looks like I need to get some better measurement tools. Maybe the pulse length is more like the ~5 ms, of the gaps, and I'm seeing some sort of beat frequency between scope and detected RF. 5ms and 101 points *is* more consistent with a total sweep duration of ~second. This is where an old style analog scope would be nice.
I don't know for certain if my observations listening to the radio receiver were correct.
Thanks, Kent
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On Sat, Sep 4, 2021 at 11:54 AM, Rainer Schaack wrote:
My assumption is that this comes from the voltage divider R40/R39 for
detection of USB voltage.
This not used in code. Need check: Si5351 start work - generate 8MHz clock for aic3204 codec aic3204 start work - send data over i2s bus to CPU
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Re: Sweep and stimulus timing
H/H4 in my firmware work more faster. It use 4x faster ADC for measure/faster i2c bus for control si5351 chip/improved timings
I made lot of code optimization for allow get good sweep speed.
H4 use DSP processing and faste CPU (this allow little faster processing) on it measure ~600-765 points / sec (depend form frequency range) if need measure only one port speed ~1.5x faster (need enable only measured port trace)
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Re: Sweep and stimulus timing
Thanks for running the test and posting the three images. Were you using a NanoVNA-H with 101 data points? I was not able to correlate the images with the operation of my two devices as I understand them.
In listening to the signals on a radio receiver, my NanoVNA-H4 appears to do a sweep in slightly less than 1 second. With 401 data points, that would allow a little less than 2.5 milliseconds per data point.
My NanoVNA-H appears to do a sweep of 101 data points in roughly 300 milliseconds. That would allow approximately 3 milliseconds for each data point.
I don't know for certain if my observations listening to the radio receiver were correct.
Thanks, Kent
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Roger Need
Richard Clemens
