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Posted: 11/25/2021 1:20:51 PM EDT
[Last Edit: MK4Mod0]
I finally got my GAP DX Challenger antenna up and connected.
It is located about 60 feet from my entry box.
In the entry box  I have a ground wire to a ground rod directly under the box, as well as a MFJ spake gap where the LMR400 connected to the LMR400 up to the radio.

The question is, Should I add a ground rod and spark gap out t the antenna...would there be any benefit, or worse a down side to doubling up the spark gaps?

Link Posted: 11/25/2021 1:46:38 PM EDT
[Last Edit: aa777888-2] [#1]
No, you don't need an additional stage of lightning protection. You would, however, be well advised to get a better quality arrestor. PolyPhaser or Morgan are the brands you seek.
Link Posted: 11/25/2021 1:57:58 PM EDT
[#2]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By aa777888-2:
No, you don't need an additional stage of lightning protection. You would, however, be well advised to get a better quality arrestor. PolyPhaser or Morgan are the brands you seek.
View Quote
OK , Thanks for the advice !
Link Posted: 11/25/2021 4:49:06 PM EDT
[#3]
Go with MOrgan Mfg protectors. In my opiion, they are superior to Polyphasers. Cheaper too. Besides having ceramic gas discharge tubes, Morgans come with static dissipating coils, quality DC blocking caps and bleed resistors included. Polyphasers don't. Polyphasers only come with ceramic discharge tubes and DC blocking caps. Any time high voltage discharges through a ceramic discharge tube, it generates a strong RF spike in the receiver. It may be a problem during winter storms or other weather conditions that generate a lot of static in the antennas.
This is particularly important in long wire antennas, like dipoles, especially if uninsulated wire is used. Your vertical may be DC grounded at the base. If it is, static should not be a big problem.
Link Posted: 11/25/2021 5:23:25 PM EDT
[Last Edit: Frank_B] [#4]
ARRL has a detailed book on bonding and grounding practices. LINK
Link Posted: 11/25/2021 6:20:38 PM EDT
[#5]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gyprat:
Go with MOrgan Mfg protectors. In my opiion, they are superior to Polyphasers. Cheaper too. Besides having ceramic gas discharge tubes, Morgans come with static dissipating coils, quality DC blocking caps and bleed resistors included. Polyphasers don't. Polyphasers only come with ceramic discharge tubes and DC blocking caps. Any time high voltage discharges through a ceramic discharge tube, it generates a strong RF spike in the receiver. It may be a problem during winter storms or other weather conditions that generate a lot of static in the antennas.
This is particularly important in long wire antennas, like dipoles, especially if uninsulated wire is used. Your vertical may be DC grounded at the base. If it is, static should not be a big problem.
View Quote

+1 on this. I use Morgan suppressors for all these reasons, too.
Link Posted: 11/25/2021 7:11:36 PM EDT
[Last Edit: smullen] [#6]
Who all sells these Morgan Mfg surge suppressors???

I looked on my favorite DXengineeing, checked Amazon as well.. No love...

Link Posted: 11/25/2021 7:13:43 PM EDT
[#7]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Frank_B:
ARRL has a detailed book on bonding and grounding practices.
View Quote


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...
Link Posted: 11/25/2021 7:18:22 PM EDT
[Last Edit: MK4Mod0] [#8]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:
Who all sells these Morgan Mfg surge suppressors???

I looked on my favorite DXengineeing, checked Amazon as well.. No love...
View Quote
https://surgestop.com/coaxial-arrestors/m-303-.html
Link Posted: 11/25/2021 9:09:04 PM EDT
[#9]
The Industrial Communications Engineers surge suppression products are now offered by Array Solutions, they are also DC grounded and work well.

https://www.arraysolutions.com/surge-and-rf-protection
Link Posted: 11/26/2021 2:23:33 AM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:
Originally Posted By Frank_B:
ARRL has a detailed book on bonding and grounding practices.


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...



I have it

It convinced me to forget about most of the grounding and just leave the entire shack  disconnected  from the rest of the world when not being used.
Link Posted: 11/26/2021 8:56:59 AM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:
Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...
View Quote


No, it is mostly plain English. Very readable. My only (minor) complaint is that the author seems to spend as much time telling you what info he is going to tell you as he does giving you the actual info.
Link Posted: 11/26/2021 9:35:15 AM EDT
[#12]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Emoto:


No, it is mostly plain English. Very readable. My only (minor) complaint is that the author seems to spend as much time telling you what info he is going to tell you as he does giving you the actual info.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Emoto:
Originally Posted By smullen:
Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...


No, it is mostly plain English. Very readable. My only (minor) complaint is that the author seems to spend as much time telling you what info he is going to tell you as he does giving you the actual info.



Tell them what you are going to tell them
tell them
tell them what you told them.

he is probably former military, that is SOP
Link Posted: 11/26/2021 11:14:04 AM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mach:



I have it

It convinced me to forget about most of the grounding and just leave the entire shack  disconnected  from the rest of the world when not being used.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mach:
Originally Posted By smullen:
Originally Posted By Frank_B:
ARRL has a detailed book on bonding and grounding practices.


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...



I have it

It convinced me to forget about most of the grounding and just leave the entire shack  disconnected  from the rest of the world when not being used.


Lol,
Why is that???

Did they just go so far over the top that you felt you could never get it done right or even close to their standards?

Like you could spend 2 million to ground a $200.00 radio?
Link Posted: 11/26/2021 11:44:12 AM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mach:
1. Tell them what you are going to tell them
2. tell them
3. tell them what you told them.

he is probably former military, that is SOP
View Quote


I don't disagree with that structure, but if we consider that to be 3 sections (I inserted numbers in your post), section 1 should not be as large as section 2. Sections 1 and 3 should be concise and brief, and section 2 should be the meat of the sandwich and have the most content.
Link Posted: 11/26/2021 1:51:44 PM EDT
[#15]
For those that have recommended the Morgan arrestors, one question. On the side of them, looks to be at the 239/N connector to radio, there's a smaller threaded pole with a nut on it. Is that for connecting to ground, in the event that the unit itself isn't mounted to it, or is it for something else?

I was looking at the Alpha-Delta ones with the replaceable cores, trying to see if the Polyphaser or Morgan ones have any kind of field service options or if they're a replaceable/disposable unit when activated.
Link Posted: 11/26/2021 5:25:12 PM EDT
[#16]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:


Lol,
Why is that???

Did they just go so far over the top that you felt you could never get it done right or even close to their standards?

Like you could spend 2 million to ground a $200.00 radio?
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:
Originally Posted By Mach:
Originally Posted By smullen:
Originally Posted By Frank_B:
ARRL has a detailed book on bonding and grounding practices.


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...



I have it

It convinced me to forget about most of the grounding and just leave the entire shack  disconnected  from the rest of the world when not being used.


Lol,
Why is that???

Did they just go so far over the top that you felt you could never get it done right or even close to their standards?

Like you could spend 2 million to ground a $200.00 radio?



Yep and Yes.
Link Posted: 11/26/2021 5:49:32 PM EDT
[Last Edit: MK4Mod0] [#17]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MK4Mod0:
OK , Thanks for the advice !
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MK4Mod0:
Originally Posted By aa777888-2:
No, you don't need an additional stage of lightning protection. You would, however, be well advised to get a better quality arrestor. PolyPhaser or Morgan are the brands you seek.
OK , Thanks for the advice !
I bought a Morgan brand, says it shipped today.
So far the antenna receives like a champ...heard Washington and New Mexico yesterday..........have not transmitted voice yet, but tried JT65 and I have some issues to iron out.
Radio goes into transmit , seems to put out the wattage, with a 1:1 on the SWR...but My JT65 software is not decoding and I get no responses to my CQ, even tho I can hear other people transmitting..
That will be the first thing to solve.

I hope to get on the ARFCOM net Tuesday night, and give voice a try.
Link Posted: 12/17/2021 12:24:53 AM EDT
[#18]
Originally Posted By MK4Mod0:
I finally got my GAP DX Challenger antenna up and connected.
It is located about 60 feet from my entry box.
In the entry box  I have a ground wire to a ground rod directly under the box, as well as a MFJ spake gap where the LMR400 connected to the LMR400 up to the radio.

The question is, Should I add a ground rod and spark gap out t the antenna...would there be any benefit, or worse a down side to doubling up the spark gaps?

https://www.ar15.com/media/mediaFiles/25600/thumbnail_IMG_2739-2180683.jpg
View Quote

@MK4Mod0

I forgot to ask, what bands are you getting able to work with that antenna?

What is it?

How are you liking it so far
and how long is the run from the antenna to your radio???

Link Posted: 12/17/2021 6:01:33 PM EDT
[#19]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By smullen:

@MK4Mod0

I forgot to ask, what bands are you getting able to work with that antenna?

What is it?

How are you liking it so far
and how long is the run from the antenna to your radio???

View Quote
I've been working mostly on 40 made a contact on JT65 and had a rag chew with a guy in Michigan via voice.
I was shooting 40 watts and I got a 5-9 from him, and said I sounded good.
I was also listening to some guys on 160.

I still haven't figured my JT65 issue...even tho I did the one QSO, my propagation via PSK Reporter does not look good.

The antenna seems to receive very well, I've heard a lot of guys all over the country, But I've done mostly listening .
The GAP Challenger is good for 80, 40, 20, 15, 12,10, and 6 and you choose the Cap from a drop down menu with 5 choices from 3.5-3.9 MHZ.

So far I like it a lot.
I haven't put the radials on yet and that could be part of the problem.
I chose to mount it on a post and want to call them to see if and how they suggest  running the radial.
I have limited ground space and that part of the reason I went with a vertical.
I was told it would work well without the radial, but if I can get them run that would be a huge plus.

The run to the house is 75 feet of LMR400 buried  to an entry box on the side of the house.
I have a lightning suppressor there and a ground wire hook to the suppressor down to a 4 foot ground rod completely driven into the ground.
From the entry box to my radio is about 25 more feet of LMR400 to a switch so that I can choose either my TS-590S or TS440S.

Band conditions as they are makes things a little difficult and without a panadapter or frequency scope it a lot of hunt and peck, scanning.

I am looking at options for the TS590 to add a panadapter..................the wife will love this one !!!




Link Posted: 12/17/2021 7:52:28 PM EDT
[#20]
KF7P has a great webstore with a broad selection of grounding components, among other things like the Morgan arrestors.  His entrance panels are sweet though pricey (IMO).
Link Posted: 12/17/2021 8:08:21 PM EDT
[#21]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By JimmyFallon:
KF7P has a great webstore with a broad selection of grounding components, among other things like the Morgan arrestors.  His entrance panels are sweet though pricey (IMO).
View Quote


Yea, his boxes are a bit pricey for me.
I just ordered the one off DXengineering a few lightning arrestors and some LMR400...

Next week or so I hope to order an antenna or at least pick up a bunch ground rods and other grounding shit...  My God do the little goodies add up..

This might be worse than all the electrical shit I bought for my car audio system...
Link Posted: 12/17/2021 9:10:54 PM EDT
[#22]
Link Posted: 12/18/2021 1:29:38 PM EDT
[#23]
I'm thinking of rehanging my G5RV as well, just to have another antenna and something that I can switch back and forth to see  just how the Challenger is for comparison.
The Wife will love this !!!
Link Posted: 12/19/2021 12:39:25 AM EDT
[Last Edit: RED_5] [#24]
Link Posted: 1/26/2022 12:01:11 AM EDT
[#25]
Speaking of coax lightning surpe protectors, what about Alpha Delta?  Specifically the ATT3G500 version.  This is the brand that Dave Casler recommends - FWIW.  He says the PolyPhaser type are not professional vs the ADs.

https://www.dxengineering.com/parts/alf-att3g50uhp


Link Posted: 1/26/2022 6:50:55 AM EDT
[#26]
Link Posted: 1/26/2022 6:59:27 AM EDT
[#27]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Merlin:
Speaking of coax lightning surpe protectors, what about Alpha Delta?  Specifically the ATT3G500 version.  This is the brand that Dave Casler recommends - FWIW.  He says the PolyPhaser type are not professional vs the ADs.

https://www.dxengineering.com/parts/alf-att3g50uhp

https://static.dxengineering.com/global/images/prod/xlarge/alf-att3g50uhp_xl.jpg
View Quote


I don't have enough experience to say which brand is best, but that is exactly what I ended up with for the coax before it goes into my house. Might have been due to a Casler video; I can't remember.

Anyway, HRO has them for a little less than DXE: https://www.hamradio.com/detail.cfm?pid=H0-005102
Link Posted: 1/26/2022 12:14:33 PM EDT
[Last Edit: smullen] [#28]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By RED_5:


whatever.  there are probably more PP's in use commercially than any other brand.

not that there are not better out there, PP were (are?) an industry standard.
View Quote
No matter what brand you pick, I'm sure there are always better..  

I don't have them in place yet, but I picked up 3 Poly Phasers  to put in an enclosure that will go about face height on my Tower, then be grounded and bonded.  

Between Sub freezing temps, having both Covid and Pneumonia for the last month or so, I've kinda been on a project pause....

When the temps get back in the 40s/50s, I'll get back at it.  As for now, I'm just stocking up parts needed for the job.
Link Posted: 3/26/2022 6:38:45 AM EDT
[#29]
This seems like the right thread to ask this question:

Are the lightning suppressors totally weatherproof? In other words, it is ok to have them outside, exposed to all the elements?
Link Posted: 3/26/2022 7:27:47 AM EDT
[#30]
The Morgan units are not waterproof. I use a plastic container dropped over the top of the ground rod they are mounted on to keep the rain off. It's not fancy, but it's worked for ten years.
Link Posted: 4/3/2022 2:39:20 PM EDT
[#31]
Originally Posted By Emoto:
This seems like the right thread to ask this question:

Are the lightning suppressors totally weatherproof? In other words, it is ok to have them outside, exposed to all the elements?
View Quote

Originally Posted By aa777888-2:
The Morgan units are not waterproof. I use a plastic container dropped over the top of the ground rod they are mounted on to keep the rain off. It's not fancy, but it's worked for ten years.
View Quote


I did write to the people at Alpha Delta, who said:

The units themselves are weatherproofed, however the mating male connectors
are not.  You will need to either put the units in a weathertight enclosure
or seal the mating male connectors with a product such as Coax Seal which is
available from any ham dealer such as HRO, DX Eng, R&L, etc.
Link Posted: 4/3/2022 3:24:35 PM EDT
[#32]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bric2000:



Yep and Yes.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bric2000:
Originally Posted By smullen:
Originally Posted By Mach:
Originally Posted By smullen:
Originally Posted By Frank_B:
ARRL has a detailed book on bonding and grounding practices.


Probably a lot of really dry reading and overly head scientific theory, but I ordered this book Wednesday...



I have it

It convinced me to forget about most of the grounding and just leave the entire shack  disconnected  from the rest of the world when not being used.


Lol,
Why is that???

Did they just go so far over the top that you felt you could never get it done right or even close to their standards?

Like you could spend 2 million to ground a $200.00 radio?



Yep and Yes.


Exactly

The only thing most hams do with all the grounding they do is prevent RF spikes from damaging radios when there is a strike in the proximity of the station. They do not protect from lightning strikes even though many think they do.

I get better protection by having the equipment, the antenna feed lines, the station ground, and the AC power AND AC grounds all disconnected from the rest of the world when not in use.

My coax is connected to nothing
My 600 ohm ladder line is disconnected with a big knife switch
My station ground bar is disconnected from the ground rod with a big knife switch
And all the station AC plugs ( except the 240 v amp ) is on the same big power strip that is unplugged thereby unplugging the AC ground too.
The amp is unplugged from the 240v receptacle


Link Posted: 4/4/2022 4:22:39 PM EDT
[#33]
Since this is kind of an antenna thread, I thought I'd put this in here.

Last night I was having a bit of a rag-chew QSO with someone in NYS and a guy from MI called break so we had him join the conversation. All 3 of us have only been hams for about a year. The MI guy says how he has worked in electronics for 28 years, etc., and then tells how he put up this dipole he made and was getting high SWR where he wanted to be, so he and his buddy folded back the ends onto themselves and re-measured SWR and it made no difference. I think he said they did this a couple of times with the same "no change" result. He was going to go out and buy some other wire but the expense was a problem.

So... I asked him... does the wire have insulation on it? The answer was yes.

I suggested that he strip off a bunch of the insulation and then try folding it back so that the folded back part is bare and the part it is folded back onto is also bare.

All of his years "working in electronics" and somehow this did not click for him.
Link Posted: 4/4/2022 4:50:34 PM EDT
[Last Edit: Mach] [#34]
Folding antenna wire back on itself will resonate at the new folded length, it will have a slightly larger bandwidth because it acts like a thicker wire

SWR is really meaningless. he needed to measure resonance to see what was happening

the original wire had a high impedance for the freq he used and when he folded it back it still had a high impedance. He cant tell anything other than that with SWR

What was he trying to do or show?

having insulation on the wire will add a bit of capacitance  compared to bare wire touching and that will affect resonance but not really any more than a single insulated wire compared to a single bare wire. The added capacitance chances the velocity factor of the wire.

More than likely he probably cut the dipole to the 468/freq  formula which is for 14 gauge bare wire so his SWR was high because it was insulated wire  and it was resonating at a lower frequency and he just wasnt folding enough of the wire tip. All my antennas  have the insulated wire, folding insulated wire, I twist it, adds some capacitance at the end which means you need an even shorter length. Or he folded too much back and missed the resonance length because he was doing too much at a time and ended up on the other side of the resonance with the wire being too short
Link Posted: 4/4/2022 5:02:18 PM EDT
[#35]
I didn't know you could measure resonance. How does one do that?
Link Posted: 4/4/2022 5:03:29 PM EDT
[#36]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Emoto:
I didn't know you could measure resonance. How does one do that?
View Quote


with an antenna analyzer or a VNA
Link Posted: 4/4/2022 5:06:14 PM EDT
[#37]
at resonance the antenna will have zero inductance and zero capacitance ( not really zero but they both zero out with each other )  with a pure resistive reading.
Link Posted: 4/4/2022 5:09:19 PM EDT
[Last Edit: Mach] [#38]
an example would be the screwdriver you made

a short vertical ( mobile antenna not 1/4 wave )   is very capacitive

the screw driver adds inductance, it is a variable inductor, and you adjust it so the inductance cancels out the capacitance of the short vertical to put the vertical in resonance .
Link Posted: 4/4/2022 5:16:12 PM EDT
[#39]
resonance is simply the current and the voltage are in phase

capacitance makes the current lag the voltage

inductance makes the voltage lag the current

when the inductance and capacitance cancel each other the voltage and current are in phase

that is what you are doing when loading an antenna say with a base coil.

an in phase current and voltage means they peak at the same time in the same place on the wire maximizing the radiation of the energy peak
Link Posted: 4/4/2022 7:09:38 PM EDT
[#40]
Thanks for all that! I need to find that on the NanoVNA...
Link Posted: 4/4/2022 8:47:55 PM EDT
[#41]
Well said Mach!  @ Emoto If the frequency sweep is wide enough the resonant point can be spotted, the negative information is that the antenna could be resonant with an "R" value of ( for example) 250 Ohms which would be a VSWR of 5:1. Sometimes it's easier with a broad sweep to look for the low VSWR point and work from there. The correct point will be at resonance and a VSWR of 1:1 Resonance at a high VSWR will be far from the desired frequency. HTH
73,
Rob
Link Posted: 4/4/2022 9:59:22 PM EDT
[#42]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By robmkivseries70:
Resonance at a high VSWR will be far from the desired frequency. HTH
View Quote

Not necessarily. An antenna could be resonant at the desired frequency, but with a resistance of say 300 ohms, leading to a high SWR in a 50 ohm system.

With an analyzer generally you can look at resistance (R) and reactance (X) separately which is very helpful in some kinds of measurements. Tuning an off-center fed dipole for example is an exercise in futility without separate R and X.
Link Posted: 4/4/2022 10:57:58 PM EDT
[#43]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MK4Mod0:
I bought a Morgan brand, says it shipped today.
So far the antenna receives like a champ...heard Washington and New Mexico yesterday..........have not transmitted voice yet, but tried JT65 and I have some issues to iron out.
Radio goes into transmit , seems to put out the wattage, with a 1:1 on the SWR...but My JT65 software is not decoding and I get no responses to my CQ, even tho I can hear other people transmitting..
That will be the first thing to solve.

I hope to get on the ARFCOM net Tuesday night, and give voice a try.
View Quote


Are you running software in the bakground which syncs your computer clock?  If not, do so. That will fix your decoding issue.
Link Posted: 4/5/2022 6:27:37 AM EDT
[#44]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By robmkivseries70:
Well said Mach!  @ Emoto If the frequency sweep is wide enough the resonant point can be spotted, the negative information is that the antenna could be resonant with an "R" value of ( for example) 250 Ohms which would be a VSWR of 5:1. Sometimes it's easier with a broad sweep to look for the low VSWR point and work from there. The correct point will be at resonance and a VSWR of 1:1 Resonance at a high VSWR will be far from the desired frequency. HTH
73,
Rob
View Quote


Link Posted: 4/5/2022 10:10:06 AM EDT
[Last Edit: robmkivseries70] [#45]
@Emoto
Which antenna is this? It looks good enough for 20M and up in frequency with a tuner, depending upon the feed line.
@Gamma762
I can agree, no problem. I do see feeding a folded dipole, for example, with 50 Ohm coax as more of a design problem.
73,
Rob
Link Posted: 4/5/2022 10:35:37 AM EDT
[#46]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By robmkivseries70:
@Emoto
Which antenna is this? It looks good enough for 20M and up in frequency with a tuner, depending upon the feed line.
@Gamma762
I can agree, no problem. I do see feeding a folded dipole, for example, with 50 Ohm coax as more of a design problem.
73,
Rob
View Quote


End-fed that was supposed to get me onto 160, LOL.
Link Posted: 4/5/2022 11:18:55 AM EDT
[#47]
I remember that, did you send the antenna back? I remember we discussed adding more wire to the length.
73,
Rob
Link Posted: 4/5/2022 11:53:22 AM EDT
[#48]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gamma762:

Not necessarily. An antenna could be resonant at the desired frequency, but with a resistance of say 300 ohms, leading to a high SWR in a 50 ohm system.

With an analyzer generally you can look at resistance (R) and reactance (X) separately which is very helpful in some kinds of measurements. Tuning an off-center fed dipole for example is an exercise in futility without separate R and X.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gamma762:
Originally Posted By robmkivseries70:
Resonance at a high VSWR will be far from the desired frequency. HTH

Not necessarily. An antenna could be resonant at the desired frequency, but with a resistance of say 300 ohms, leading to a high SWR in a 50 ohm system.

With an analyzer generally you can look at resistance (R) and reactance (X) separately which is very helpful in some kinds of measurements. Tuning an off-center fed dipole for example is an exercise in futility without separate R and X.


a simple center fed dipole should have  a resonant impedance of somewhere close to 50-74  ohms or so depending on height above ground and conductivity of the ground

A folded dipole will have an impedance at resonance of around 300  ohms which is why people feed them with 300 ohm  or other open line

it just depends on the type of antenna and how you want to feed it
Link Posted: 4/5/2022 12:38:59 PM EDT
[#49]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By robmkivseries70:
I remember that, did you send the antenna back? I remember we discussed adding more wire to the length.
73,
Rob
View Quote


Not yet. That is on the table and may end up being what happens. They are communicating with me in a reasonable manner, so it may end up turning out well. We shall see.
Link Posted: 4/5/2022 1:50:21 PM EDT
[#50]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Emoto:


Not yet. That is on the table and may end up being what happens. They are communicating with me in a reasonable manner, so it may end up turning out well. We shall see.
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Originally Posted By Emoto:
Originally Posted By robmkivseries70:
I remember that, did you send the antenna back? I remember we discussed adding more wire to the length.
73,
Rob


Not yet. That is on the table and may end up being what happens. They are communicating with me in a reasonable manner, so it may end up turning out well. We shall see.


How long is the wire?
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