Could you forward a link to the $1.65 strippers please?
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
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On 9/23/21 10:01 AM, Larry Macionski via groups.io wrote: I have bought strip tools from Banggood.com instead of Ham Radio Outlet. Granted they take 3-4 weeks but they were like $1.65 USD.. I always order multiples as if ordering one and waiting a month it's broken is counterproductive.
The ones i get have a "plug" you can rotate for RG-174, RG-58/59, RG-6U/RG8X, or RG8/9913 that sets razor blade depth..
I surplus my extras- at ham fests for a $1 more. or as "door prizes" at Club meetings trading them for tickets in the 50/50 raffle.. winner gets a whole, not a half of the stripper..
Always demand the whole stripper... This is true even if not a ham..
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Hi, Larry,
Any chance of a link or name? I've looked on Bangood and found a "universal" coax stripper which could be useful but only goes down to 3.2mm. I use a lot of RG176/4 which is much thinner. The one you describe with the plug seems ideal for my use.
Thanks - Michael.
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On 23/09/2021 18:01, Larry Macionski via groups.io wrote: I have bought strip tools from Banggood.com instead of Ham Radio Outlet. Granted they take 3-4 weeks but they were like $1.65 USD.. I always order multiples as if ordering one and waiting a month it's broken is counterproductive.
The ones i get have a "plug" you can rotate for RG-174, RG-58/59, RG-6U/RG8X, or RG8/9913 that sets razor blade depth..
I surplus my extras- at ham fests for a $1 more. or as "door prizes" at Club meetings trading them for tickets in the 50/50 raffle.. winner gets a whole, not a half of the stripper..
Always demand the whole stripper... This is true even if not a ham..
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Got a link to those Coax Strippers ? I searched Banggood and all I got were a lot more expensive !! 73, Dick, W1KSZ ________________________________ From: [email protected] < [email protected]> on behalf of Larry Macionski via groups.io <am_fm_radio@...> Sent: Thursday, September 23, 2021 10:01 AM To: [email protected] < [email protected]> Subject: Re: [nanovna-users] Stripping Coax I have bought strip tools from Banggood.com instead of Ham Radio Outlet. Granted they take 3-4 weeks but they were like $1.65 USD.. I always order multiples as if ordering one and waiting a month it's broken is counterproductive. The ones i get have a "plug" you can rotate for RG-174, RG-58/59, RG-6U/RG8X, or RG8/9913 that sets razor blade depth.. I surplus my extras- at ham fests for a $1 more. or as "door prizes" at Club meetings trading them for tickets in the 50/50 raffle.. winner gets a whole, not a half of the stripper.. Always demand the whole stripper... This is true even if not a ham..
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Re: PC Boards for QEX Step Attenuator Available
If you are asking about my design, it is -1dB at 500MHz and -2dB at 1GHz.
73, Mike AF7KR
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I have bought strip tools from Banggood.com instead of Ham Radio Outlet. Granted they take 3-4 weeks but they were like $1.65 USD.. I always order multiples as if ordering one and waiting a month it's broken is counterproductive.
The ones i get have a "plug" you can rotate for RG-174, RG-58/59, RG-6U/RG8X, or RG8/9913 that sets razor blade depth..
I surplus my extras- at ham fests for a $1 more. or as "door prizes" at Club meetings trading them for tickets in the 50/50 raffle.. winner gets a whole, not a half of the stripper..
Always demand the whole stripper... This is true even if not a ham..
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Re: Antenna / VNA Question
Looks like TLDetails:
Vince N2JRS
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Chris K2STP Sent: Thursday, September 23, 2021 12:06 PM To: [email protected]Subject: Re: [nanovna-users] Antenna / VNA Question Roger, What software are you using with those screen shots showing "Transmission Line Details"? I have never seen that display before....? Thanks in advance.... -- Regards, Chris K2STP
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Re: Antenna / VNA Question
Roger,
What software are you using with those screen shots showing ¡°Transmission Line Details¡±? I have never seen that display before¡.? Thanks in advance¡.
--
Regards,
Chris K2STP
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Re: Antenna / VNA Question
Very good explanation Roger.
I might add to get ride of USB interference I put a choke on the USB cable and it kept it isolated and the Nano VNA calculated the same values on HF frequencies with no ground issues with it plugged in or not.
Of course if you have your hand on the VNA it does affect it.
I also have my VNA on plexiglass
Kinda reminder not to be holding on to it when making a measuremnt. Also keeps stuff away from the VNA.
De K8HTB Joe
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Re: PC Boards for QEX Step Attenuator Available
What is the throughput loss with all attenuators bypassed by the
switches, at 500 MHz?
*Clyde K. Spencer*
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On Thu, Sep 23, 2021 at 10:31 AM vbifyz <3ym3ym@...> wrote: For a poor ham's step attenuator design, look here:
Works well up to about 500MHz. The blowback is very small because of the
type of "switches" used.
Feel free to order on JLCPCB. The design is under CC license.
73, Mike AF7KR
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Re: PC Boards for QEX Step Attenuator Available
For a poor ham's step attenuator design, look here:
Works well up to about 500MHz. The blowback is very small because of the type of "switches" used.
Feel free to order on JLCPCB. The design is under CC license.
73, Mike AF7KR
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Re: Antenna / VNA Question
On Wed, Sep 22, 2021 at 05:49 PM, Andrew Kurtz wrote:
Wow, I didn¡¯t realize that! Thanks...
Getting - and using - a NanoVNA really starts a learning curve! And - there's SO much to learn . . . . . -- Doug, K8RFT
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Yes the center conductor...
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Re: PC Boards for QEX Step Attenuator Available
Good evening All. Dick K9IVB, is there any chance that you could email me a copy of that article? Fred - N4CLA If you want to send it direct, it is n40cla@.... On Wed, Sep 22, 2021 at 3:11 PM Roger Need via groups.io <sailtamarack= [email protected]> wrote: On Tue, Sep 21, 2021 at 11:11 PM, dick faust wrote:
The author discusses this some and there are numerous response graphs in
the
QEX supp files. Can you read the article or do you need a copy
Dick K9IVB
I am not an ARRL member so I don't have access to the article.
Roger
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Re: Antenna / VNA Question
Wow, I didn¡¯t realize that! Thanks...
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On Sep 22, 2021, at 3:49 PM, Roger Need via groups.io <sailtamarack@...> wrote:
I have attached some example that illustrate this point. Lets say your antenna measured 75 ohms resistance and 0 ohms reactance at 9 MHz. You installed 43.5 feet of generic 300 ohm tubular cable (away from nearby objects). You measured with your NanoVNA and got an SWR of 1.58 with R=0 and X near 0. Looks good because this corresponds to 1/2 wavelength of cable at 9 MHz. It was then shorted to 32.6 feet or 3/8 wavelengths. Now the SWR is 12.78 with R = 144 and X = -263. Next it is shortened to 21.8 feet or 1/4 wavelength. SWR increases to 23.6 with R=1179 an X = -9.857. It is clear that length has a dramatic effect on what you measure. These values were all calculated with the downloadable Transmission Line Details program. Annotated screenshots attached
However if we used RG-59 or RG-6 which has a characteristic impedance of 75 ohms the SWR measured at the NanoVNA would be close to 1.5 for all cable lengths above.
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Re: Antenna / VNA Question
On Wed, Sep 22, 2021 at 11:00 AM, Andrew Kurtz wrote:
Just measured dipole directly without twin-lead; right on expectations!
Reactance was 0 at 9, 18.3, 27.8, 37.8, 47.3, 58.5, 67, 77.6, and 86 MHz.
Alternate ones, when X moved from capacitive to inductive, had lowest R and
SWR.
Begs a question: for practical use, isn¡¯t the gratifying direct measurement
on the dipole less ¡°real¡± or useful than the measurement downstairs using
the feedline?
I mentioned in another post that the transmission line acts as an impedance transformer. What you see at the end of your 300 ohm twin line will depend on the following factors: antenna feedpoint impedance, characteristics of transmission line and transmission line length. I have attached some example that illustrate this point. Lets say your antenna measured 75 ohms resistance and 0 ohms reactance at 9 MHz. You installed 43.5 feet of generic 300 ohm tubular cable (away from nearby objects). You measured with your NanoVNA and got an SWR of 1.58 with R=0 and X near 0. Looks good because this corresponds to 1/2 wavelength of cable at 9 MHz. It was then shorted to 32.6 feet or 3/8 wavelengths. Now the SWR is 12.78 with R = 144 and X = -263. Next it is shortened to 21.8 feet or 1/4 wavelength. SWR increases to 23.6 with R=1179 an X = -9.857. It is clear that length has a dramatic effect on what you measure. These values were all calculated with the downloadable Transmission Line Details program. Annotated screenshots attached However if we used RG-59 or RG-6 which has a characteristic impedance of 75 ohms the SWR measured at the NanoVNA would be close to 1.5 for all cable lengths above. Roger
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Re: PC Boards for QEX Step Attenuator Available
On Tue, Sep 21, 2021 at 11:11 PM, dick faust wrote:
The author discusses this some and there are numerous response graphs in the
QEX supp files. Can you read the article or do you need a copy
Dick K9IVB
I am not an ARRL member so I don't have access to the article. Roger
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Re: PC Boards for QEX Step Attenuator Available
If you are interested in a board, at $3.00 ppd CONUS, please reply off line [click the ¡°Private¡± button].
The first order is sold out and there is sufficient additional interest for a second order.
I will be making a second order next week.
I expect to receive the second set boards near the end of October.
Dick K9IVB
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Re: Antenna / VNA Question
On 9/22/21 11:00 AM, Andrew Kurtz via groups.io wrote: Just measured dipole directly without twin-lead; right on expectations! Reactance was 0 at 9, 18.3, 27.8, 37.8, 47.3, 58.5, 67, 77.6, and 86 MHz. Alternate ones, when X moved from capacitive to inductive, had lowest R and SWR.
Begs a question: for practical use, isn¡¯t the gratifying direct measurement on the dipole less ¡°real¡± or useful than the measurement downstairs using the feedline? Well, sometimes you can't get to the antenna (or your being close to it perturbs its behavior) There are two approaches to this: 1) calibrate the VNA with the feedline inside the calibration plane (i.e. put the open, short, load at the end of the feedline) 2) Measure the feedline by itself, and mathematically remove it from the measurement. Both have their strong/weak points. For instance, if you measure the antenna and today it measures differently than it did last time, you still have the "is it the feedline or the antenna that changed". One interesting approach is that with antennas with distinct resonances, off resonance, it usually presents a pretty big mismatch.? So you can run your TDR sweep and get a decent measurement (since, usually, TDR is done with a short or open at the far end), and if your feedline has changed, you'll see it in the TDR
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Re: Antenna / VNA Question
Hi Andrew,
? ? The 468/f formula is based on (a) a perfect conductor and (b) a dipole antenna in free space.? In the real world, antenna systems are affected by the environment, such as a height above ground, metal objects near the antenna, the type of wire, whether it's insulated, and a host of other factors. Also, did you calibrate your NanoVNA for the frequency range of interest?? That too may play a part in what you're seeing.
Generally, 468/f will get you in the ballpark; it's best to cut a little bit long, test your antenna in its operational configuration (i.e. installed in your attic) and then adjust from there.? Also, keep in mind that it's not just about SWR and reactance...A dummy load will have a 1:1 SWR.? If it tunes up well and works well with your radio, that's all the proof you need; it's called 'antenna theory' for a reason.? A balun won't hurt either, but if it works without one then you don't need one.? Feel free to keep us updated!
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On Wednesday, September 22, 2021, 02:00:51 PM EDT, Andrew Kurtz via groups.io <adkurtz@...> wrote: Just measured dipole directly without twin-lead; right on expectations!? Reactance was 0 at 9, 18.3, 27.8, 37.8, 47.3, 58.5, 67, 77.6, and 86 MHz. Alternate ones, when X moved from capacitive to inductive, had lowest R and SWR. Begs a question: for practical use, isn¡¯t the gratifying direct measurement on the dipole less ¡°real¡± or useful than the measurement downstairs using the feedline? On Sep 22, 2021, at 1:33 PM, alan victor <avictor73@...> wrote:
?You have the antenna in the attic so I assume you can reach its center point. Maybe not. But if you can, just clip your vna to the feed point and take a measure. I had a 66 foot NVIS 40 meter antenna flat at 15 feet above the ground. Clipped the vna onto the wires, let hang, stepped away and observed its display with my spy glasses!!! Just kidding. Held, read it and it was spot on.
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Re: Antenna / VNA Question
Hooray! No... now you have divided the problem. Divide and conquer.
NOW read all of those prior emails and begin to get your head wrapped around the issue of HOW DO I GET MY ANTENNA CONNECTED TO MY TRANSMITTER?
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Dick
Larry Macionski
vh2
Chris K2STP
Roger Need
