Date   

Running ZOOM on UBUNTU 16.04 18.04 ++

Doug - W2VX
 

Hello,

For the group meetings and having zoom features for voting and polling it is
recommended to download and install the ZOOM app.

Running from FireFox or Chrome did not provide this functionality in our testong.

To install the app -

use this URL

https://support.zoom.us/hc/en-us/articles/204206269-Installing-or-updating-Zoom-on-Linux#h_89c268b4-2a68-4e4c-882f-441e374b87cb

I installed "Using the terminal" section of the instructions.

Hope that helps.

W2VX - Doug

73


--

Call sign W2VX
Digital PSK31 FT8 FT8call 20Mtr 40Mtr
D-Star XRF002a APRS northwest.aprs2.net
DMR monitoring TG310
70cm 2,6,10,20,40Mtr
Monitor W6EK Repeater - 145.430 -600, PL162.2
Rigs IC7100,IC7300
Location : Near Sacramento CA



--
Doug W2VX
w2vx@...
message 530 368 5703
Auburn CA


SFARC Net - Thu, 10/29/2020 #cal-notice

sfarc@w6ek.groups.io Calendar <noreply@...>
 

SFARC Net

When:
Thursday, 29 October 2020
7:30pm to 8:30pm
(GMT-07:00) America/Los Angeles

Where:
W6EK Repeater - 145.430 -600, PL162.2

Description:
Check-in for Club updates from Officers and members, QSTs and more. Everyone is welcome!


NVIS and Happy Hour Propagation with Ben Witvliet PE5B

Jef - N5JEF
 

Forwarding this link (below) to a 20-minute video because NVIS, and because the presenter, Dr. Ben Witvliet, is probably the best researcher on NVIS that I know of. 

- Jef

---------- Forwarded message ---------
From: Dr. Nathaniel A. Frissell Ph.D. via TangerineSDR <tangerinesdr@...>
Date: Thu, Oct 29, 2020 at 4:58 PM
Subject: Re: [TangerineSDR] HamSCI Bi-Weekly Telecon this Thursday - NVIS and Happy Hour Propagation with Ben Witvliet PE5B
To: hamsci@... <hamsci@...>, TangerineSDR Listserv <tangerinesdr@...>
Cc: Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell@...>


Hi all,

 

Here is the recording of Ben’s excellent NVIS talk:

https://scranton.zoom.us/rec/share/NvIUF1scpQYsjjEn76ThEPyn_kkdiEz_hnTVI3va4C8as7_5owVxXipkGBR2CEVM.FW6KY-VxBCC96u6i?startTime=1603998147000

 

73 de Nathaniel W2NAF

 

From: Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell@...>
Sent: Tuesday, October 27, 2020 10:40 AM
To: hamsci@...; TangerineSDR Listserv <tangerinesdr@...>
Subject: HamSCI Bi-Weekly Telecon this Thursday - NVIS and Happy Hour Propagation with Ben Witvliet PE5B

 

Hi HamSCI,
 
This Thursday, October 29th is our bi-weekly HamSCI Zoom telecon at 1900z / 3 PM Eastern.

If you are asked for a password, it is “hamsci”.

 

Dr. Ben Witvliet, PE5B will give a presentation on Near Vertical Incidence Skywave (NVIS) propagation. Ben will explain the propagation mechanism, related elevation angles, and the splitting of NVIS waves into two fully independent circularly polarized waves, the ordinary (O) and extraordinary (X) waves. Contrary to popular belief, circular polarization is very important on 3.5 and 7 MHz! To prove that this is not just theory, he provides elevation angle measurements and O and X polarization measurements. He will explain the intriguing 'Happy Hour' propagation interval. Also, Ben will demonstrate through simulation and measurement that the optimum antenna height for NVIS is neither 'as low aspossible' and nor 'a quarter wave length'. And that there is a difference between optimum height for transmission and reception. Duration 20-30 minutes, questions after the presentation.

 

dr. ing. Ben Witvliet [pronounce 'Wit-fleet’] (PE5B) is a radio amateur since the age of 13 in 1974. He lived in New Guinea, The Netherlands, Monaco, Israel, Madagascar and England, where he held the callsigns PA3BXC,PA3BXC/3A2, 4X/PA3BXC, PA5BW, 5R8DS and M0IJQ. He loves CW DX, especially on the low bands. He holds 5BDXCC, obtainedwith 100 Watts and simple antennas. Since the beginning of his radio hobby he has been intrigued by antennas and propagation. He worked in high power broadcast engineering in The Netherlands and was chief engineer of the Radio Netherlands shortwave station in Madagascar, operating two 300 kW transmitters with 17 to23 dBi antennas. He currently works as a technical expert of the Radio Communications Agency of The Netherlands and continues his research in part-time at the University of Twente. Ben obtained his PhD - and the Anton Veder award - in 2015 for his research on NVIS antennas and propagation.

 

Thanks and 73 de Nathaniel W2NAF

 

— 
Dr. Nathaniel A. Frissell, Ph.D., W2NAF

HamSCI Lead
Assistant Professor
Department of Physics and Electrical Engineering
University of Scranton
(973) 787-4506

 

--
TangerineSDR mailing list
TangerineSDR@...
http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Okay, I suppose you mean Sierra Hotel India Tango, but whatever...

Congrats on the General.  Now you can build some seriously big antennas. :-)

- Jef

On Thu, Oct 29, 2020 at 3:33 PM Joshua - KK6VHH <besneatte@...> wrote:
 Jef., thanks! You are the Sam Ham In Town! 

FCC now shows my General class! wooooot! Anyway...........


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Joshua - KK6VHH
 

 Jef., thanks! You are the Sam Ham In Town! 

FCC now shows my General class! wooooot! Anyway...........

Next time I pull it down I will redo the choke.... for now I am just waiting for the next net so I can dial in the azimuth. 

Thanks again everyone! 73z^10
--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


[pr:15000] Episode #2 What Hams Do - Minorities in Amateur Radio

carl.wf6j@gmail.com
 

FYI...

Begin forwarded message:

From: "Jay Silber" <jay@...>
Subject: [pr:15000] Episode #2 What Hams Do - Minorities in Amateur Radio
Date: October 29, 2020 at 6:53:03 AM PDT
To: <pr@...>
Reply-To: jaysilber@...

For Immediate Release: 

Set your alarms for Sunday evening, November 1st, at 8 PM ET for the Premiere of “What Hams Do – Minorities in Amateur Radio.” 

This is a YouTube Premiere Presentation at: https://youtu.be/H6zVgGGn6N4. 

Click the link now to get a reminder. Subscribe to the EPA-ARRL YouTube channel and click the notification bell so you don’t miss future uploads.

In a YouTube Premiere, chat is live, and the video will be available exactly at 8 PM, November 1st. Individuals featured in the program will be available to join in conversations as the program plays. The video will be permanently available after the premiere event.

This second TV show in the What Hams Do series by the Eastern Pennsylvania Section of the ARRL focuses on minority participation in Amateur Radio in America.

Minorities are not only a vibrant part of American life, but they are also a dynamic force in Amateur Radio. This episode of What Hams Do explores the myths and facts about race in ham radio. Four minority Amateur Radio operators in Southeastern Pennsylvania describe how they've connected to this amazing hobby and discuss their view of racism in ham radio. Expanding ham radio among members of minority communities is crucial to growth in the hobby and its membership. How do we do that? Four excellent ideas from four unique ham radio operators provide a roadmap to growth.

 

Meet our guests:

Keith Perry, N3QQZ, an engineer by training and tech company owner, Keith explores his deep relationship with Amateur Radio and the events in his life that pushed him to greater achievement in the hobby.

Clint Beckett, WB3EHB, a Marine Corps veteran, describes early childhood experiences that led him into the hobby as well as well as a career in electronic communications. Clint, as an officer of the predominantly African American Delaware Valley OMIK club (founded nationally in 1952 to promote Amateur Radio in African American communities) has a very positive view of Amateur Radio when it comes to racism.

Janice Winston, KC3ORH, a recently licensed Amateur Radio operator reports on her 17 years of service to the Red Cross. Her service minded philosophy is carrying over into her role in ham radio, which she finds a very welcoming community. Janice also has a blueprint for expanding diversity in our Amateur Radio organizations.

Frank (Francisco) Rodriguez, KC3HRS, leads a ham radio on-the-air network that carries messages from disaster impacted Spanish language communities to the rest of the US. The organization, the Pennsylvania Society of Latin American Radio Operators (PASOLA) was born in the midst of Hurricane Maria's devastating impact on the island of Puerto Rico. Beyond that, Frank is a church pastor who has lost close friends and a brother to the COVID-19 pandemic. Caring for the health and welfare not only of his congregants but also of his ham radio community is an essential part of who he is. 

 

Links mentioned in TV Show #2 of What Hams Do - Minorities in Amateur Radio are:

TV Show #1 What Hams Do - Youth in Amateur Radio

https://youtu.be/8T3JmUze7JQ

Send news items about Ham Radio activities in the EPA ARRL section to:

jaysilber@...

Getting Started in Ham Radio

http://www.arrl.org/what-is-ham-radio

Checking Health and Welfare of Amateur Radio Operators, a discussion in:

https://youtu.be/WBWoN_qYEo0 or search your favorite podcast service for "What Hams Do - We're Ready"

______________________________________________

Contact info:

Jay Silber, PIC ARRL EPA Section

 




Avast logo

This email has been checked for viruses by Avast antivirus software. 
www.avast.com


_______________________________________________
pr mailing list
pr@...
To unsubscribe or change your email reflector settings, visit: https://reflector.arrl.org/mailman/listinfo/pr


[pr:15001] W PA Hams commemorate birth of commercial broadcasting - KDKA Story

carl.wf6j@gmail.com
 

FYI...

Begin forwarded message:

From: NU3Q <nu3q@...>
Subject: [pr:15001] W PA Hams commemorate birth of commercial broadcasting
Date: October 29, 2020 at 7:38:05 AM PDT
To: pr@...

_______________________________________________
pr mailing list
pr@...
To unsubscribe or change your email reflector settings, visit: https://reflector.arrl.org/mailman/listinfo/pr

73,
Carl,
WF6J
ARRL PIO


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

10 tight winds around the boom, non-overlapping, should make a good choke for this band.

- Jef

On Thu, Oct 29, 2020 at 1:52 PM Joshua - KK6VHH <besneatte@...> wrote:
Hey Jef, thanks!!!!!!

I have been wondering about that since I started this build and kept forgetting to ask!

So this will be similar to existing baulin but just wrapped around the boom instead, correct... 10 tight winds, non overlapping????

That would certainly look nicer. I feel like Harry Potter deciding on a magic wand. Magical talismans should always look nice.

I feel more like I constructed a magical wizard staff than a scientific instrument. Anyway, I digress.... 

We should do an antenna building workshop.

--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Joshua - KK6VHH
 

J pole in a tree is the next one on the list. Just need to acquire some robust aluminum angle bracket....
--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Joshua - KK6VHH
 

Hey Jef, thanks!!!!!!

I have been wondering about that since I started this build and kept forgetting to ask!

So this will be similar to existing baulin but just wrapped around the boom instead, correct... 10 tight winds, non overlapping????

That would certainly look nicer. I feel like Harry Potter deciding on a magic wand. Magical talismans should always look nice.

I feel more like I constructed a magical wizard staff than a scientific instrument. Anyway, I digress.... 

We should do an antenna building workshop.

--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Joshua -

Very nice to see someone putting this kind of effort into antenna building (and experimenting.)

You could probably make a neater, and somewhat more effective choke if you coiled the coax tightly around the boom instead of making a larger diameter offboard coil.

Another thought—With all those tall pines, you might find that you do better with an omnidirectional antenna suspended high up a tree, rather than a gain antenna on a mast.  Height is often more effective than watts.

- Jef

On Thu, Oct 29, 2020 at 12:54 PM Joshua - KK6VHH <besneatte@...> wrote:
Soooo cool! Thanks for all the photos and info/insight everyone!

I really like the hairpin match... looks much cleaner than the baulin

I ended up redoing my baulin with some longer and thicker coax (RG8X) and routing it out the back of the boom.

This worked like a charm... now my driven elements are short enough to incorporate my slide in tuning bits... got this tuned up to 145mhz ISH
with an SWR of about 1.8.... NICE... I painted it green hoping it would blend in with the trees and that worked really well ( if you're wondering what 
that pick of "nothing" is)





--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Joshua - KK6VHH
 

Soooo cool! Thanks for all the photos and info/insight everyone!

I really like the hairpin match... looks much cleaner than the baulin

I ended up redoing my baulin with some longer and thicker coax (RG8X) and routing it out the back of the boom.

This worked like a charm... now my driven elements are short enough to incorporate my slide in tuning bits... got this tuned up to 145mhz ISH
with an SWR of about 1.8.... NICE... I painted it green hoping it would blend in with the trees and that worked really well ( if you're wondering what 
that pick of "nothing" is)





--
KK6VHH - Joshua

piratesinteepees.org
youtube.com/piratesinteepees


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Oh, and it's a good idea to form a choke at the feedpoint with several turns of coax tightly wrapped together around the boom, to reduce the inevitable common-mode current you'll get due to feeding a balanced antenna with unbalanced feedline.  You don't want your coaxial cable to have current on the outside of the shield, trying to be part of the antenna.

- Jef


On Thu, Oct 29, 2020 at 11:19 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Greg -

At work so gotta keep this brief.

The hairpin, or beta match, has some advantages in this application—mainly that it is symmetrical so it doesn't distort the pattern as a gamma match would at these shorter wavelengths, and it is easy to tune by adjusting the distance between the parallel legs of the transmission line stub that it creates.  Efficiency is excellent due to its electrical simplicity.

Slight disadvantage compared to the gamma match is that it requires that the driven element be split at the middle, so mechanical simplicity and strength might be slightly reduced.

Generally speaking, I think the gamma match can be a good choice for larger, HF Yagis, and the hairpin (or beta) match is a very good choice for VHF-UHF Yagis.  However, most commercial VHF Yagis that I have seen use a gamma match, and then you're supposed to pay attention to whether the antenna, vertically polarized, has the gamma match up, or down (usually down) due to the distortion of the pattern.  Of course, if the antenna is up high on a mountain-top, then tilting the pattern down could be good…

The length of wire is important, but not critical in this application, since the match is obtained by cutting your two quarter-wave monopoles slightly shorter than calculated resonance length, and then moving the parallel sides slightly inward or outward for best impedance match. You can see that with my construction, using the standard dimensions given in the drawing, the legs are pretty close to parallel and I got a good match (something less than 1.5:1 if I remember correctly.)  I don't remember whether that was at 144.830, or 146 MHz.

How much a good match matters, depends mostly on your coax—how long and how lossy.  Then, as long as your transmitter can deal with any mismatch, it doesn't really matter.

The antenna itself doesn't care at all about a feedline mismatch.  It will radiate as it always does, based on its structure in relation to operating wavelength (less any resistive losses, which should be insignificant here), whatever power it is fed.  

- Jef


On Thu, Oct 29, 2020 at 10:49 AM Greg D <ko6th.greg@...> wrote:
Hi Jef,

Thanks for the photo on the Hairpin match.  To fill in a detail, the instruction text linked to specifies the length of the wire at 5 inches, though it doesn't say if that's the exposed part, or whether the 1/8" or so that is "consumed" with the solder at the ends makes a difference.  As a percentage of 5", that 1/8" might be significant.  How critical is the length of the wire, and how it is shaped and tuned?

Interesting that they "tune" the antenna by adjusting the distance between the two halves of the driven element, instead of trimming the length of them.  I hadn't seen that technique before.

A question on this morning's coffee break net, perhaps you could offer an opinion on...  Is there a preference on the sort of match being used?  Some just attach the coax to the two sides of the dipole, and call it good.  Some use the hairpin, some a Gamma match (feeding one side some distance out on the driven element), some a Delta match (feeding both sides some distance out).  I can see how the Gamma and Delta matches would be unwieldy with a flexible antenna such as this, but how much does the hairpin really contribute to the antenna's performance?

Thanks,

Greg  KO6TH

p.s.  To anyone interested, the club has had a pair of 2m beam construction projects, for which we have videos posted.  For entertainment purposes, take a look:

February 2012:  https://www.youtube.com/watch?v=4itu5xuiJoE
August, 2017:  https://www.youtube.com/watch?v=Gf7ils0Xf0o


Jef - N5JEF wrote:
Here's a closeup of the hairpin match on the one I built:

image.png

On Thu, Oct 29, 2020 at 6:24 AM Jef Allbright <jef@...> wrote:
Joshua -

Back in January 2015 we held an antenna-building party at my place and six of us built "tape measure" 3-element Yagis for 2 meters. Quick and easy to make, and the flexible elements fold up for easy transport. About 7.2 dB gain, optimized for front-to-back ratio, and used a simple "hairpin" match for impedance matching.


image.png







On Wed, Oct 28, 2020 at 10:06 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Greg -

At work so gotta keep this brief.

The hairpin, or beta match, has some advantages in this application—mainly that it is symmetrical so it doesn't distort the pattern as a gamma match would at these shorter wavelengths, and it is easy to tune by adjusting the distance between the parallel legs of the transmission line stub that it creates.  Efficiency is excellent due to its electrical simplicity.

Slight disadvantage compared to the gamma match is that it requires that the driven element be split at the middle, so mechanical simplicity and strength might be slightly reduced.

Generally speaking, I think the gamma match can be a good choice for larger, HF Yagis, and the hairpin (or beta) match is a very good choice for VHF-UHF Yagis.  However, most commercial VHF Yagis that I have seen use a gamma match, and then you're supposed to pay attention to whether the antenna, vertically polarized, has the gamma match up, or down (usually down) due to the distortion of the pattern.  Of course, if the antenna is up high on a mountain-top, then tilting the pattern down could be good…

The length of wire is important, but not critical in this application, since the match is obtained by cutting your two quarter-wave monopoles slightly shorter than calculated resonance length, and then moving the parallel sides slightly inward or outward for best impedance match. You can see that with my construction, using the standard dimensions given in the drawing, the legs are pretty close to parallel and I got a good match (something less than 1.5:1 if I remember correctly.)  I don't remember whether that was at 144.830, or 146 MHz.

How much a good match matters, depends mostly on your coax—how long and how lossy.  Then, as long as your transmitter can deal with any mismatch, it doesn't really matter.

The antenna itself doesn't care at all about a feedline mismatch.  It will radiate as it always does, based on its structure in relation to operating wavelength (less any resistive losses, which should be insignificant here), whatever power it is fed.  

- Jef


On Thu, Oct 29, 2020 at 10:49 AM Greg D <ko6th.greg@...> wrote:
Hi Jef,

Thanks for the photo on the Hairpin match.  To fill in a detail, the instruction text linked to specifies the length of the wire at 5 inches, though it doesn't say if that's the exposed part, or whether the 1/8" or so that is "consumed" with the solder at the ends makes a difference.  As a percentage of 5", that 1/8" might be significant.  How critical is the length of the wire, and how it is shaped and tuned?

Interesting that they "tune" the antenna by adjusting the distance between the two halves of the driven element, instead of trimming the length of them.  I hadn't seen that technique before.

A question on this morning's coffee break net, perhaps you could offer an opinion on...  Is there a preference on the sort of match being used?  Some just attach the coax to the two sides of the dipole, and call it good.  Some use the hairpin, some a Gamma match (feeding one side some distance out on the driven element), some a Delta match (feeding both sides some distance out).  I can see how the Gamma and Delta matches would be unwieldy with a flexible antenna such as this, but how much does the hairpin really contribute to the antenna's performance?

Thanks,

Greg  KO6TH

p.s.  To anyone interested, the club has had a pair of 2m beam construction projects, for which we have videos posted.  For entertainment purposes, take a look:

February 2012:  https://www.youtube.com/watch?v=4itu5xuiJoE
August, 2017:  https://www.youtube.com/watch?v=Gf7ils0Xf0o


Jef - N5JEF wrote:
Here's a closeup of the hairpin match on the one I built:

image.png

On Thu, Oct 29, 2020 at 6:24 AM Jef Allbright <jef@...> wrote:
Joshua -

Back in January 2015 we held an antenna-building party at my place and six of us built "tape measure" 3-element Yagis for 2 meters. Quick and easy to make, and the flexible elements fold up for easy transport. About 7.2 dB gain, optimized for front-to-back ratio, and used a simple "hairpin" match for impedance matching.


image.png







On Wed, Oct 28, 2020 at 10:06 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Rob Newburn
 

Hi Josh,

Here are pics of the hairpin match and whatever the coax match is called. 

Good luck with yours!

73,
Rob KM6YKX


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Greg D
 

Hi Jef,

Thanks for the photo on the Hairpin match.  To fill in a detail, the instruction text linked to specifies the length of the wire at 5 inches, though it doesn't say if that's the exposed part, or whether the 1/8" or so that is "consumed" with the solder at the ends makes a difference.  As a percentage of 5", that 1/8" might be significant.  How critical is the length of the wire, and how it is shaped and tuned?

Interesting that they "tune" the antenna by adjusting the distance between the two halves of the driven element, instead of trimming the length of them.  I hadn't seen that technique before.

A question on this morning's coffee break net, perhaps you could offer an opinion on...  Is there a preference on the sort of match being used?  Some just attach the coax to the two sides of the dipole, and call it good.  Some use the hairpin, some a Gamma match (feeding one side some distance out on the driven element), some a Delta match (feeding both sides some distance out).  I can see how the Gamma and Delta matches would be unwieldy with a flexible antenna such as this, but how much does the hairpin really contribute to the antenna's performance?

Thanks,

Greg  KO6TH

p.s.  To anyone interested, the club has had a pair of 2m beam construction projects, for which we have videos posted.  For entertainment purposes, take a look:

February 2012:  https://www.youtube.com/watch?v=4itu5xuiJoE
August, 2017:  https://www.youtube.com/watch?v=Gf7ils0Xf0o


Jef - N5JEF wrote:

Here's a closeup of the hairpin match on the one I built:

image.png

On Thu, Oct 29, 2020 at 6:24 AM Jef Allbright <jef@...> wrote:
Joshua -

Back in January 2015 we held an antenna-building party at my place and six of us built "tape measure" 3-element Yagis for 2 meters. Quick and easy to make, and the flexible elements fold up for easy transport. About 7.2 dB gain, optimized for front-to-back ratio, and used a simple "hairpin" match for impedance matching.


image.png







On Wed, Oct 28, 2020 at 10:06 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Here's a closeup of the hairpin match on the one I built:

image.png

On Thu, Oct 29, 2020 at 6:24 AM Jef Allbright <jef@...> wrote:
Joshua -

Back in January 2015 we held an antenna-building party at my place and six of us built "tape measure" 3-element Yagis for 2 meters. Quick and easy to make, and the flexible elements fold up for easy transport. About 7.2 dB gain, optimized for front-to-back ratio, and used a simple "hairpin" match for impedance matching.


image.png







On Wed, Oct 28, 2020 at 10:06 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef


Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Joshua -

Back in January 2015 we held an antenna-building party at my place and six of us built "tape measure" 3-element Yagis for 2 meters. Quick and easy to make, and the flexible elements fold up for easy transport. About 7.2 dB gain, optimized for front-to-back ratio, and used a simple "hairpin" match for impedance matching.


image.png







On Wed, Oct 28, 2020 at 10:06 AM Jef - N5JEF via groups.io <jef=jefallbright.net@groups.io> wrote:
Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef


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Re: Three Element Yagi / Beam built with gifted/salvaged parts. #antennas

Jef - N5JEF
 

Joshua -

Nice work.

Keep in mind that the length of the driven elements (plural) should each be a quarter wave at the geometric mean of the frequency range of interest.  It's not the tip to tip length of the two elements that matters.  it's the length of each element that you are pushing current into.  You put current in, and it takes a certain amount of time, depending on frequency, for the current to reach the end of the quarter wave element.  It looks like you used a pretty thick boom, so maybe that accounts for the measurement discrepancy.

Also note that a Yagi does not present 50 ohms at its input.  The input impedance will always be something less, so the SWR will always be greater than the 1:1 you might be hoping for.  If the Yagi driven elements are showing 35 about ohms, for example, then your SWR will be about 1.5, for example.  (By the way, that's about the best you can every get, in theory, from a mobile quarter wave whip, which has an input impedance, in theory, of 36 ohms.  I always makes me wonder when people claim to get 1:1 on their mobile quarter wave whip...

Normally, if you want to get a better impedance match to a Yagi, you use a hairpin, or gamma match at the antenna.  But depending on your cable type and length, an SWR of 1.5 or even 2 to 1, is not a really a problem at VHF.

- Jef

On Wed, Oct 28, 2020 at 9:50 AM Joshua - KK6VHH <besneatte@...> wrote:
Here's my test setup... waiting on 239 barrel connector for tuning, reception on this thing is amazing even at ground level!



--
KK6VHH - Joshua

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