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Earle D Wilkinson (6Y5EW) Home page: Email address: earle.wilkinson@... Echolink: 6Y5RA On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <earle.wilkinson@...> wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960 high
pass filter with 147.360 as the split on the low pass filter, that is minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and 147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
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On 12/20/21 12:27 AM, Earle Wilkinson wrote: Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <earle.wilkinson@...>
wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960 high
pass filter with 147.360 as the split on the low pass filter, that is minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and 147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
Two issues that arise: #1 The NanoVNA only has a limited number of frequency steps (101,201,401, depending on which firmware and model) unless you're using software on an external computer that does multiple scans. So, if you set your span to, say, 147 to 148 MHz, then you'll get a measurement every 10 kHz (with 101 points).? Solution here is to use one of the many software packages that will talk to the NanoVNA and make multiple scans and combine them. #2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate enough.? I don't recall the spec, but let's say it's on the order of 10 ppm (good for a TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
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On Mon, Dec 20, 2021 at 07:21 AM, Jim Lux wrote:
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate enough.? I
don't recall the spec, but let's say it's on the order of 10 ppm (good for a
TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
( #window-197633454 )
My fw allow made internal 26MHz TCXO correction (see CONFIG->EXPERT SETTING->TCXO) Power on device, set 26MHz CW output Wait near 5-10min for device warm Measure output frequency Enter this value as TCXO Save confog. Now as minimum up to 100MHz Nano have only +-2Hz error. (Error bigger on more high frequency)
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Thanks, DiSlord for this! It's awfully close, and granted, for precision accuracy remember that we're comparing a $50-$75 device against oscilloscopes or spectrum analyzers which cost many times that....You get what you pay for, most of the time anyway. Tuning duplexer cans isn't for the faint of heart, but the NanoVNA will get you close enough to get into the ballpark.
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On Monday, December 20, 2021, 10:31:52 AM EST, DiSlord <dislordlive@...> wrote: On Mon, Dec 20, 2021 at 07:21 AM, Jim Lux wrote:
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate enough.? I
don't recall the spec, but let's say it's on the order of 10 ppm (good for a
TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
( #window-197633454 )
My fw allow made internal 26MHz TCXO correction (see CONFIG->EXPERT SETTING->TCXO) Power on device, set 26MHz CW output Wait near 5-10min for device warm Measure output frequency Enter this value as TCXO Save confog. Now as minimum up to 100MHz Nano have only +-2Hz error. (Error bigger on more high frequency)
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Interesting video by W2AEW on this subject
"How to tune a duplexer with a NanoVNA V2plus4 | is it possible?"
Roger
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Thanks for the response will let you know the outcome
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
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On Mon, Dec 20, 2021, 10:21 AM Jim Lux <jim@...> wrote: On 12/20/21 12:27 AM, Earle Wilkinson wrote:
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <earle.wilkinson@...
wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960 high
pass filter with 147.360 as the split on the low pass filter, that is minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and 147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms
impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
Two issues that arise:
#1 The NanoVNA only has a limited number of frequency steps
(101,201,401, depending on which firmware and model) unless you're using
software on an external computer that does multiple scans. So, if you
set your span to, say, 147 to 148 MHz, then you'll get a measurement
every 10 kHz (with 101 points). Solution here is to use one of the many
software packages that will talk to the NanoVNA and make multiple scans
and combine them.
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate
enough. I don't recall the spec, but let's say it's on the order of 10
ppm (good for a TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
|
Remember, the difference between “accuracy” and “precision” is important.
Accuracy has to do with the degree to which an instrument can determine a measured value compared to the actual value, independent of the method of measurement.
Precision is the degree to which an instrument can display the actual value.
For precision, think about measuring a length; does the scale read in 10ths of an inch, 100ths of an inch? And how accurate are those markings on the scale?
DaveD
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On Dec 20, 2021, at 13:18, Earle Wilkinson <earle.wilkinson@...> wrote:
?Thanks for the response will let you know the outcome
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 10:21 AM Jim Lux <jim@...> wrote:
On 12/20/21 12:27 AM, Earle Wilkinson wrote:
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <earle.wilkinson@...
wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960 high
pass filter with 147.360 as the split on the low pass filter, that is minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and 147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms
impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
Two issues that arise:
#1 The NanoVNA only has a limited number of frequency steps
(101,201,401, depending on which firmware and model) unless you're using
software on an external computer that does multiple scans. So, if you
set your span to, say, 147 to 148 MHz, then you'll get a measurement
every 10 kHz (with 101 points). Solution here is to use one of the many
software packages that will talk to the NanoVNA and make multiple scans
and combine them.
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate
enough. I don't recall the spec, but let's say it's on the order of 10
ppm (good for a TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
|
Think of it in golfing terms. It's like trying to putt with a 'mashie'. (personally I prefer a #2 wood to putt)
Mike C.
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On 12/20/2021 1:48 PM, Dave Daniel wrote: Remember, the difference between “accuracy” and “precision” is important.
Accuracy has to do with the degree to which an instrument can determine a measured value compared to the actual value, independent of the method of measurement.
Precision is the degree to which an instrument can display the actual value.
For precision, think about measuring a length; does the scale read in 10ths of an inch, 100ths of an inch? And how accurate are those markings on the scale?
DaveD
On Dec 20, 2021, at 13:18, Earle Wilkinson <earle.wilkinson@...> wrote:
?Thanks for the response will let you know the outcome
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 10:21 AM Jim Lux <jim@...> wrote:
On 12/20/21 12:27 AM, Earle Wilkinson wrote:
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <earle.wilkinson@...
wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960 high
pass filter with 147.360 as the split on the low pass filter, that is minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and 147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms
impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
Two issues that arise:
#1 The NanoVNA only has a limited number of frequency steps
(101,201,401, depending on which firmware and model) unless you're using
software on an external computer that does multiple scans. So, if you
set your span to, say, 147 to 148 MHz, then you'll get a measurement
every 10 kHz (with 101 points). Solution here is to use one of the many
software packages that will talk to the NanoVNA and make multiple scans
and combine them.
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate
enough. I don't recall the spec, but let's say it's on the order of 10
ppm (good for a TCXO) - at 147 MHz, that means it could be off by 1470 Hz.
|
Can someone please help me. Which of the following is correct
I would figure the one that has a 50 ohm impedance but the pattern looks
wrong. What am I doing wrong.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
toggle quoted message
Show quoted text
On Mon, Dec 20, 2021, 3:01 PM Mike C. <mg@...> wrote: Think of it in golfing terms. It's like trying to putt with a 'mashie'.
(personally I prefer a #2 wood to putt)
Mike C.
On 12/20/2021 1:48 PM, Dave Daniel wrote:
Remember, the difference between “accuracy” and “precision” is important.
Accuracy has to do with the degree to which an instrument can determine a measured value compared to the actual value, independent of the method of
measurement.
Precision is the degree to which an instrument can display the actual
value.
For precision, think about measuring a length; does the scale read in 10ths of an inch, 100ths of an inch? And how accurate are those markings on
the scale?
DaveD
On Dec 20, 2021, at 13:18, Earle Wilkinson <earle.wilkinson@...>
wrote:
?Thanks for the response will let you know the outcome
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 10:21 AM Jim Lux <jim@...> wrote:
On 12/20/21 12:27 AM, Earle Wilkinson wrote:
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
On Mon, Dec 20, 2021, 3:18 AM Earle Wilkinson <
earle.wilkinson@...
wrote:
New at this.
I got myself an NanoVNA 2 version 4.
Everyone says best thing ever happened.
Better than sliced cheese.
My problem is that I a sticular when it comes to accuracy.
I would like to check my club stations duplexer accuracy on 147.960
high
pass filter with 147.360 as the split on the low pass filter, that is
minus
600 kc split.
Now her is my problem I can only set my markers at 147.300 and
147.900.
Not the exact repeater frequency.
Will the difference of 60 hz make a difference in the accuracy of the
tuning insertion loss etc.
I realise that I need to be accurate at least with the 50 ohms
impedance.
Thanks for your response.
Earle D Wilkinson
(6Y5EW)
Home page:
Email address: earle.wilkinson@...
Echolink: 6Y5RA
Two issues that arise:
#1 The NanoVNA only has a limited number of frequency steps
(101,201,401, depending on which firmware and model) unless you're
using
software on an external computer that does multiple scans. So, if you
set your span to, say, 147 to 148 MHz, then you'll get a measurement
every 10 kHz (with 101 points). Solution here is to use one of the
many
software packages that will talk to the NanoVNA and make multiple scans
and combine them.
#2 The 28 MHz oscillator in the NanoVNA isn't necessarily accurate
enough. I don't recall the spec, but let's say it's on the order of 10
ppm (good for a TCXO) - at 147 MHz, that means it could be off by 1470
Hz.
|
Roger Need
Mike C.
