Re: cut/lengthen vertical antenna wire
Hi Doug,
Lots of good advice has already been given about the antenna feedpoint impedance.
Here are some important questions about your measurement:
1. Did you measure at the feedpoint?
2. If not, and you measured through some length of coax, did you calibrate your NanoVNA at the end of that coax?
3. If you are measuring through some length of coax, do you have a choke balun on the coax near the antenna feedpoint?
Dave NU8A
|
On 7/26/2022 9:05 PM, Jim Lux wrote: But yeah, if you're throwing a dipole for 40m up in a tree, measurement to the nearest inch/cm is probably good enough. This brings me to a thought that I have had for many years.? Just to nit pick a bit more for science, I hear people say that they "cut the dipole to 50 ohm resonance" when in actuality I believe that they are cutting the dipole to an impedance match.? I've never taken the time to model the antenna in software (on my bucket list to learn this skill) but I really wonder what that does to the radiation pattern.? Probably insignificant on HF frequencies but it would be interesting to put a measurement on the difference. 73, Joe, K1ike
|
I too was once a slide rule user, the Pickett / Collins C-19T. Microwave Path calculation rule. Used it up until the advent of computer calculation programs. Anything's an improvement on doing it manually!! By the way vh2, the link you provided has really good info. But if you really want to get a super slide rule fix, try the following link to an all electronic virtual slide rule program (with multiple variations of slide rules) using full graphics and movable slide. Really neat. Also, Roger, I was most interested in your detailed description of the phase and timing of space communications. Not many of us have been privileged to work in that world. Ted......(KD7AQO) -----------------------------------------From: "vh2" To: " [email protected]" Cc: Sent: Tuesday July 26 2022 7:12:48PM Subject: Re: [nanovna-users] Antennas I have one: a Hemmi 153: />
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of D. Scott MacKenzie via groups.io Sent: Tuesday, July 26, 2022 9:47 PM To: [email protected] Subject: Re: [nanovna-users] Antennas I also have some 8' Pickett and K&E instructional sliderules and a dietzen transparent one that goes on an overhead projector - old school all the way ,:) On Tue, Jul 26, 2022, 21:23 Zack Widup wrote: > I have a large K&E slide rule that must have 26 or so scales on it. I > also have a 6 inch Pickett that we used to call the "Pocket Pickett" > :-) > > Zack W9SZ > > On Tue, Jul 26, 2022 at 6:22 PM Stephen W9SK wrote: > > > I have two different Post slide rules from back in the day, but my > > most valued one is specifically designed for electronics formula use > > by Picket (reactance, resonance, resistance, etc). > > > > Stephen W9SK > > > > > > -----Original Message----- > > From: [email protected] On Behalf Of > KENT > > BRITAIN > > Sent: Tuesday, July 26, 2022 4:04 PM > > To: [email protected] > > Subject: Re: [nanovna-users] Antennas > > > > One must wonder if you ever owned a slide rule? hihi > > > > (Still own my eye saving yellow one by Picket) > > > > I recently saw an article for a 20 Meter beam with dimensions in > > 1/10,000ths of an inch. > > Someone needs to slap that lad up side of the head with a K&E slide > > rule!Guess he also needed to establish the exact temp the Aluminum > > should be at for that measurement. > > "Why be approximately correct when you can be precisely wrong!" Tom > Clark > > W3IWI > > > > > > For what it's worth, at last count I own 8 Network Analyzers. 3 > > Nano's > on > > various work benches and the big one is a 40 GHz HP 8510. That's > > about > 100 > > kg of analyzer. > > On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm > > loads. I had those loads on the 8510 and they were pretty bad above a > few > > Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load > > for your calibrations. The short and open seemed fine. Kent > > > > > > > > > > > > > > On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list < > > list@...> wrote: > > > > And forgets to say whether these are Imperial Gallons (defined as > > 4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 > cubic > > inches-whatever an inch might have been at the time, though today > > the US and UK agree that an inch is 25.4 mm by definition-which is > > 3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.] > > > > Yours terribly pedantically, > > > > Robin, G8DQX > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Links: ------ [1] /g/nanovna-users/files[2] /g/nanovna-users/leave/11119600/4866111/1865567994/xyzzy
|
I had a college Slide Rule class after the USAF (1970). The instructor took a full-sized K&E DeciLon and pulled the slide 2/3 out.
Then he flexed the two ends down so that it looked like a bow. He released it and it worked perfectly.
Then he said, “OK, try that with a Pickett!”
Larry
AC9OX
|
I have one: a Hemmi 153:
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of D. Scott MacKenzie via groups.io Sent: Tuesday, July 26, 2022 9:47 PM To: [email protected]Subject: Re: [nanovna-users] Antennas I also have some 8' Pickett and K&E instructional sliderules and a dietzen transparent one that goes on an overhead projector - old school all the way ,:) On Tue, Jul 26, 2022, 21:23 Zack Widup <w9sz.zack@...> wrote: I have a large K&E slide rule that must have 26 or so scales on it. I
also have a 6 inch Pickett that we used to call the "Pocket Pickett"
:-)
Zack W9SZ
On Tue, Jul 26, 2022 at 6:22 PM Stephen W9SK <stephen@...> wrote:
I have two different Post slide rules from back in the day, but my
most valued one is specifically designed for electronics formula use
by Picket (reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum
should be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3
Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's
about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches-whatever an inch might have been at the time, though today
the US and UK agree that an inch is 25.4 mm by definition-which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
My sister teaches math at the University of Wisconsin. She has one of those
8 foot slide rules in her office and was taking it to a classroom to
demonstrate. A student passed her and said "You know, they make calculators
now that are a lot smaller."
:-)
Zack W9SZ
<>
Virus-free.
www.avast.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
toggle quoted message
Show quoted text
On Tue, Jul 26, 2022 at 8:47 PM D. Scott MacKenzie <kb0fhp@...> wrote: I also have some 8' Pickett and K&E instructional sliderules and a dietzen
transparent one that goes on an overhead projector - old school all the way
,:)
On Tue, Jul 26, 2022, 21:23 Zack Widup <w9sz.zack@...> wrote:
I have a large K&E slide rule that must have 26 or so scales on it. I also
have a 6 inch Pickett that we used to call the "Pocket Pickett"
:-)
Zack W9SZ
On Tue, Jul 26, 2022 at 6:22 PM Stephen W9SK <stephen@...> wrote:
I have two different Post slide rules from back in the day, but my most
valued one is specifically designed for electronics formula use by Picket
(reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum
should
be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm
load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches—whatever an inch might have been at the time, though today the
US
and UK agree that an inch is 25.4 mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
I also have some 8' Pickett and K&E instructional sliderules and a dietzen
transparent one that goes on an overhead projector - old school all the way
,:)
toggle quoted message
Show quoted text
On Tue, Jul 26, 2022, 21:23 Zack Widup <w9sz.zack@...> wrote: I have a large K&E slide rule that must have 26 or so scales on it. I also
have a 6 inch Pickett that we used to call the "Pocket Pickett"
:-)
Zack W9SZ
On Tue, Jul 26, 2022 at 6:22 PM Stephen W9SK <stephen@...> wrote:
I have two different Post slide rules from back in the day, but my most
valued one is specifically designed for electronics formula use by Picket
(reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum should
be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches—whatever an inch might have been at the time, though today the US
and UK agree that an inch is 25.4 mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
One more slide rule off-topic, please. I have in my possession a slide rule picked up on the trashbin at Ames Lab IA State.? It is bamboo, and has the note 'This slide rule has been furnished as a replacement due to the War effort.? A fee of $1 can be sent with this slide rule for a new slide rule before July 31, 1942'.Needless to say I still have it on my 'In Case of Emergency ' shelf. WA0VYU? Sent from the all new AOL app for Android On Tue, Jul 26, 2022 at 8:06 PM, Jim Lux<jimlux@...> wrote: On 7/26/22 4:03 PM, KENT BRITAIN wrote: ? One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in 1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide rule!Guess he also needed to establish the exact temp the Aluminum should be at for that measurement. You may laugh, but sometimes, small changes in dimensions are important, and therefore so is temperature. For Aluminum, one might see a length change of 0.2% (and corresponding resonant frequency change) for a temperature change of 100C.? 100C sounds like a lot, but between a cold night in Winter, and a hot day in Summer (particularly if the aluminum is shiny), that's not an unreasonable temperature delta. If your antenna is in space, a 100 degree change from full sun to full shade is pretty common. But on the ground, maybe a 50C swing is more likely - that is a 0.1% length change, the gain doesn't change much (0.2%) but more important is the phase change of 0.2 degrees (due to the rapid change in reactance). 0.2 degrees isn't a lot, but if you're trying to form nulls, 0.2 degrees turns a perfect null into a -40dB null.? Large arrays forming a radio telescope care about this kind of thing. You don't want the apparent source to be in a different place in the sky. In a more extreme case - When measuring the range to a spacecraft, we send a signal to the spacecraft, which transmits it back, and we compare the phase of the outgoing and the incoming signal. A properly designed system can make this measurement to about 1 part in 10^15.? Let's put that into context - it's about 10^9 km to Jupiter (at opposition). So that's 10^12 meters.? We're making that measurement to 1 mm.? (it's about 36 degrees phase difference at Ka-band - 32 GHz). So we need to know not only the temperature of the antennas at both ends, but the temperatures of the waveguide and feedlines.? (and the gravitational and thermal distortion of the DSN antenna, etc.). As for *why* - by making precise measurements of range (to cm) and velocity (to mm/2) we can very accurately measure the orbit/trajectory of a spacecraft, and from that, we can measure the gravitational field of Jupiter, and from that we can infer what Jupiter's internal structure might be. But yeah, if you're throwing a dipole for 40m up in a tree, measurement to the nearest inch/cm is probably good enough.
|
I have a large K&E slide rule that must have 26 or so scales on it. I also
have a 6 inch Pickett that we used to call the "Pocket Pickett"
:-)
Zack W9SZ
toggle quoted message
Show quoted text
On Tue, Jul 26, 2022 at 6:22 PM Stephen W9SK <stephen@...> wrote: I have two different Post slide rules from back in the day, but my most
valued one is specifically designed for electronics formula use by Picket
(reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum should
be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches—whatever an inch might have been at the time, though today the US
and UK agree that an inch is 25.4 mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
On 7/26/22 4:03 PM, KENT BRITAIN wrote: One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in 1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide rule!Guess he also needed to establish the exact temp the Aluminum should be at for that measurement. You may laugh, but sometimes, small changes in dimensions are important, and therefore so is temperature. For Aluminum, one might see a length change of 0.2% (and corresponding resonant frequency change) for a temperature change of 100C. 100C sounds like a lot, but between a cold night in Winter, and a hot day in Summer (particularly if the aluminum is shiny), that's not an unreasonable temperature delta. If your antenna is in space, a 100 degree change from full sun to full shade is pretty common. But on the ground, maybe a 50C swing is more likely - that is a 0.1% length change, the gain doesn't change much (0.2%) but more important is the phase change of 0.2 degrees (due to the rapid change in reactance). 0.2 degrees isn't a lot, but if you're trying to form nulls, 0.2 degrees turns a perfect null into a -40dB null. Large arrays forming a radio telescope care about this kind of thing. You don't want the apparent source to be in a different place in the sky. In a more extreme case - When measuring the range to a spacecraft, we send a signal to the spacecraft, which transmits it back, and we compare the phase of the outgoing and the incoming signal. A properly designed system can make this measurement to about 1 part in 10^15. Let's put that into context - it's about 10^9 km to Jupiter (at opposition). So that's 10^12 meters. We're making that measurement to 1 mm. (it's about 36 degrees phase difference at Ka-band - 32 GHz). So we need to know not only the temperature of the antennas at both ends, but the temperatures of the waveguide and feedlines. (and the gravitational and thermal distortion of the DSN antenna, etc.). As for *why* - by making precise measurements of range (to cm) and velocity (to mm/2) we can very accurately measure the orbit/trajectory of a spacecraft, and from that, we can measure the gravitational field of Jupiter, and from that we can infer what Jupiter's internal structure might be. But yeah, if you're throwing a dipole for 40m up in a tree, measurement to the nearest inch/cm is probably good enough.
|
Hi Scott,
As an aside, I have used talc as a lube for bamboo slide rules over the decades. My old Post Versalog II, (with leather case, and both in MINT condition), had small amounts of talc placed in the groves, (by myself), of the bamboo, over the years I used it, and it works very well to this day, still slides like butter...
Just thought I would pass that on to you, as you collect them... My father taught me that trick.
I have no idea if it harms the sliderule, but mine seems to have survived use of talc as a lube...
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
toggle quoted message
Show quoted text
On 7/26/22 17:30, D. Scott MacKenzie wrote: I collect sliderules. I have approximately 300. Pickets. Post, K&E,
Dietzen, Chavez Roos, as well as some unique Russian and Chinese
sliderules. My favorite is a K&E 6" Deci-Lon.
On Tue, Jul 26, 2022, 19:22 Stephen W9SK <stephen@...> wrote:
I have two different Post slide rules from back in the day, but my most
valued one is specifically designed for electronics formula use by Picket
(reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum should
be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches—whatever an inch might have been at the time, though today the US
and UK agree that an inch is 25.4 mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
I collect sliderules. I have approximately 300. Pickets. Post, K&E,
Dietzen, Chavez Roos, as well as some unique Russian and Chinese
sliderules. My favorite is a K&E 6" Deci-Lon.
toggle quoted message
Show quoted text
On Tue, Jul 26, 2022, 19:22 Stephen W9SK <stephen@...> wrote: I have two different Post slide rules from back in the day, but my most
valued one is specifically designed for electronics formula use by Picket
(reactance, resonance, resistance, etc).
Stephen W9SK
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of KENT
BRITAIN
Sent: Tuesday, July 26, 2022 4:04 PM
To: [email protected]
Subject: Re: [nanovna-users] Antennas
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in
1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide
rule!Guess he also needed to establish the exact temp the Aluminum should
be at for that measurement.
"Why be approximately correct when you can be precisely wrong!" Tom Clark
W3IWI
For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on
various work benches and the big one is a 40 GHz HP 8510. That's about 100
kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm
loads. I had those loads on the 8510 and they were pretty bad above a few
Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load
for your calibrations. The short and open seemed fine. Kent
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <
list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic
inches—whatever an inch might have been at the time, though today the US
and UK agree that an inch is 25.4 mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
|
|
I have two different Post slide rules from back in the day, but my most valued one is specifically designed for electronics formula use by Picket (reactance, resonance, resistance, etc).
Stephen W9SK
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of KENT BRITAIN Sent: Tuesday, July 26, 2022 4:04 PM To: [email protected]Subject: Re: [nanovna-users] Antennas One must wonder if you ever owned a slide rule? hihi (Still own my eye saving yellow one by Picket) I recently saw an article for a 20 Meter beam with dimensions in 1/10,000ths of an inch. Someone needs to slap that lad up side of the head with a K&E slide rule!Guess he also needed to establish the exact temp the Aluminum should be at for that measurement. "Why be approximately correct when you can be precisely wrong!" Tom Clark W3IWI For what it's worth, at last count I own 8 Network Analyzers. 3 Nano's on various work benches and the big one is a 40 GHz HP 8510. That's about 100 kg of analyzer. On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm loads. I had those loads on the 8510 and they were pretty bad above a few Hundred MHz. If you can, I suggest getting a higher quality 50 Ohm load for your calibrations. The short and open seemed fine. Kent On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <list@...> wrote: And forgets to say whether these are Imperial Gallons (defined as 4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic inches—whatever an inch might have been at the time, though today the US and UK agree that an inch is 25.4?mm by definition—which is 3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.] Yours terribly pedantically, Robin, G8DQX
|
One must wonder if you ever owned a slide rule? hihi
(Still own my eye saving yellow one by Picket)
I recently saw an article for a 20 Meter beam with dimensions in 1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide rule!Guess he also needed to establish the exact temp the Aluminum should be at for that measurement.
"Why be approximately correct when you can be precisely wrong!"? Tom Clark W3IWI
For what it's worth, at last count I own 8 Network Analyzers.? 3 Nano's on various work benches and the big one is a 40 GHz HP 8510.? That's about 100 kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm loads.?? I had those loads on the 8510 and they were pretty bad above a few Hundred MHz.? If you can, I suggest getting a higher quality 50 Ohm load for your calibrations.?? The short and open seemed fine.? Kent
toggle quoted message
Show quoted text
On Tuesday, July 26, 2022 at 05:00:08 PM CDT, G8DQX list <list@...> wrote:
And forgets to say whether these are Imperial Gallons (defined as
4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231
cubic inches—whatever an inch might have been at the time, though today
the US and UK agree that an inch is 25.4?mm by definition—which is
3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
|
Re: cut/lengthen vertical antenna wire
And forgets to say whether these are Imperial Gallons (defined as 4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic inches—whatever an inch might have been at the time, though today the US and UK agree that an inch is 25.4?mm by definition—which is 3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]
Yours terribly pedantically,
Robin, G8DQX
PS: Back on topic, the joy of a wire-built antenna is that it is cheap and easy to build and *experiment* with, and one can learn a lot by just trying and seeing what happens.
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On 26/07/2022 02:54, KENT BRITAIN wrote: Much like the lad who puts 7 gal of petrol in his car, drives 243 miles,and says he got 34.71428532 miles per gallon.
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On Mon, Jul 25, 2022 at 11:26 PM, Roger Need wrote:
The ini file for NanoVNA Saver is stored in this location in Windows.
C:\Users\Your user name here\AppData\Roaming\NanoVNASaver\NanoVNASaver.ini
Thanks Roger. Using Linux Mint here. Found the file though ~/.config/NanoVNASaver/NanoVNASaver.ini But there don't appear to be any sweep settings in that file except SweepColor=@Variant(\0\0\0\x43\x1\xff\xff\xef\xef))))\0\0) Please could you look at your NanoVNASaver.ini file to see if it's different on Windows.
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On 7/26/22 3:09 AM, Ho-Ro wrote: In a .S1P file it is not an impedance that is described but S11
If you want the impedances you have to recalculate them from S11 Did you see the example 9 and 10 from my posting below (out of touchstone rev 2.0 spec)?
Example 9 (Version 1.0):
!1-port Z-parameter file, multiple frequency points Example 10 (Version 2.0):
!1-port Z-parameter file, multiple frequency points You can for sure store also impedance in a s1p file if you calculate the Z-parameter from S-parameter - this is what my tool does, fetching S11-parameter, taking a line for line with S-parameter (freq S11.re S11.im) and creating lines of normalized Z-parameter (freq R/Z0 X/Z0) preceded by a header for Z-parameter (# HZ Z RI R 50).
While the file format spec may define formats for things other than S parameters, they're not particularly common. Not to say that they don't exist, but every tool I've used only uses S parameters. They are, after all, called SnP files <grin>
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Re: cut/lengthen vertical antenna wire
Hey guys,
Bringing the? reactance to zero (if you really want that for your antenna), don't forget that there might be a coax cable involved in the measurement set-up.? That coax can move the Z of the antenna around the Smith Chart if the Z of the antenna is not exactly 50 ohms (ohmic).
Of course there are ways to solve that :-)
73
Arie PA3A
Op 26-7-2022 om 13:52 schreef Donald S Brant Jr:
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I agree with W0LEV 100% on using the phase information to guide one's tuning efforts. That valuable phase information is what puts the "Vector" in "vector network analyzer"(VNA) and is what makes it so much more useful than just a VSWR bridge or reflectometer. Having phase information is also what allows the amazing error correction to do its magic and permit such accurate measurements in such an inexpensive instrument. The ability to do so over a swept frequency range is icing on the cake, it helps you to get a feel of the behavior of the network you are measuring.
Folks who just look at an SWR number at a single frequency are missing out on much of the capability of this tool.
73, Don N2VGU
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Re: cut/lengthen vertical antenna wire
I agree with W0LEV 100% on using the phase information to guide one's tuning efforts. That valuable phase information is what puts the "Vector" in "vector network analyzer"(VNA) and is what makes it so much more useful than just a VSWR bridge or reflectometer. Having phase information is also what allows the amazing error correction to do its magic and permit such accurate measurements in such an inexpensive instrument. The ability to do so over a swept frequency range is icing on the cake, it helps you to get a feel of the behavior of the network you are measuring.
Folks who just look at an SWR number at a single frequency are missing out on much of the capability of this tool.
73, Don N2VGU
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Larry McElhiney
vh2
Stephen W9SK
Arie Kleingeld PA3A
Donald S Brant Jr