Well ... define "correctly." All simulation is an approximation of
reality. NEC-4 adds capabilities such as buried radial fields, and is
more faithful for tiny antennas than NEC-2. It treats lumped circuit
constants pretty much the same as NEC-2, however.
Last time I checked, a US
I hope you mean NEC4.
Wes N7WS
On 5/28/2018 4:19 PM, Clay Autery wrote:
Mmmm... are you saying that NEC2 handles the phsae shift through inductors
correctly/better?
"Looking for reasons to pay the license fee for NEC2)
73,
__
On 5/28/2018 5:03 PM, Clay Autery wrote:
Does NEC-4 handle the phase shift through inductors correctly?
I doubt it, but I don't know. I believe the issue is the result of the
computational model.
73, Jim K9YC
__
Elecraft mailing
Clay,
NEC-2 is public domain. NEC-4 is not, it is licensed and not free. I
believe that all flavors of EZNEC Ver 4.0 EXCEPT EZNEC/4 use the NEC-2
engine. NEC-2, as a simulator, has some deviations from reality ...
inductor modeling is one of them, conductors connected at small angles,
My mistake... doh! I meant 4.
Increment version by 2... same question... Does NEC-4 handle the phase
shift through inductors correctly?
It's a big chunk of change to get the NEC-4 license and upgrade the
front end license... need to compile multiple reasons to justify it.
Appreciate
There is no license fee for NEC2, and EZNEC and 4NEC2 both use it freely.
NEC4 is another matter ...
Dave AB7E
On 5/28/2018 4:19 PM, Clay Autery wrote:
Mmmm... are you saying that NEC2 handles the phsae shift through
inductors correctly/better?
"Looking for reasons to pay the license
Mmmm... are you saying that NEC2 handles the phsae shift through
inductors correctly/better?
"Looking for reasons to pay the license fee for NEC2)
73,
__
Clay Autery, KY5G
(318) 518-1389
On 05/28/18 15:18, Jim Brown wrote:
and is unrelated to the user interface like
On 5/28/2018 10:39 AM, John Oppenheimer wrote:
An EZNEC model using 30 feet AGL and Q=200 for the coils, has a very
close match the the reported values.
While SWR and driving Z values may be correct, there was an excellent
piece 2-part piece in QEX 3-4 years ago showing that NEC does not
Thank you very much John.
Very 73 - Mike - k9JRI
> On May 28, 2018, at 1:39 PM, John Oppenheimer wrote:
>
> Hi Mike,
>
> An EZNEC model using 30 feet AGL and Q=200 for the coils, has a very
> close match the the reported values.
>
> 20M, the antenna does not seem to degrade form a
Hi Mike,
An EZNEC model using 30 feet AGL and Q=200 for the coils, has a very
close match the the reported values.
20M, the antenna does not seem to degrade form a simple dipole with a
Gain of about 6 dBi at about 30 degrees elevation.
80M, it's about 5 dBi at 90 degrees elevation. Expected
While off topic this antenna supports an all Elecraft station.
I have very limited antenna space and my 80M/20M shortened dipole consists of
17’ center sections connected to approximately 44uH, 2.5” OD inductors with 10’
end wire sections past the inductors and terminated in end insulators.
ant
>> on 40m. If you have elevated radials you would have to put one there also
>> or just lay the radials on the ground.
>>
>> John KK9A
>>
>> [Elecraft] [OT] Antenna Question
>>
>> rick jones n3ikq
>> Sat Aug 6 22:58:39 EDT 2016
>>
&g
. Assuming that the portable 20m vertical is easily
assessable I would just clip on an inductor at the base to make it resonant
on 40m. If you have elevated radials you would have to put one there also
or just lay the radials on the ground.
John KK9A
[Elecraft] [OT] Antenna Question
rick jones n3ikq
Sat
That is a huge mismatch. Assuming that the portable 20m vertical is easily
assessable I would just clip on an inductor at the base to make it resonant
on 40m. If you have elevated radials you would have to put one there also
or just lay the radials on the ground.
John KK9A
[Elecraft] [OT
Rick,
You have been getting very good answers. You are right, the internal
ATU helps match the rig to the antenna and/or loss is negligible when
you feed the antenna directly or with low loss line (open wire).
However, I have operated with bad setups and still made contacts. I
actually
On Sat,8/6/2016 7:58 PM, rick jones via Elecraft wrote:
Ok sorry for not providing enough info! Consider this scenario: I have a
portable vertical with 4 counterpoise wires that is resonant on 20. Lets say I
want to tune the antenna up on 40.
Rick,
You're asking the wrong questions. The
A lot depends on the band. For example, your 20m vertical would have an
SWR of only 8:1 on 17m. Loss with 50' of RG-58 would be about 2 dB.
That's not insignificant, but a lot better than not being able to
operate on 17m at all. The built-in K3 tuner would have no trouble
matching it.
I am
Rick,
The usefulness of an internal tuner is highly dependent on the matched
line loss of the feedline.
If you have a feedline that has a relatively high matched line loss -
and you specified 50 feet of RG-58, then the feedline losses will be
high in the case of the antenna you propose.
A
OK a very good reality check when you look at the numbers! So I'm still trying
to figure out the usefulness of a built in tuner. Two situations come to mind:
You have no feedline and are driving a wire right out of your rig with a
counterpoise (KX3 portable operations) OR you are using it to
The SWR on the coax when you are using a 20m vertical on 40 would be
astronomical. I ran a quick EZNEC analysis of a 1/4 wave 20m vertical
with its base on the ground and got an impedance of 6.9 - j348. This
comes out to an SWR of about 187:1, which you would measure at the rig
as only 18:1
Ok sorry for not providing enough info! Consider this scenario: I have a
portable vertical with 4 counterpoise wires that is resonant on 20. Lets say I
want to tune the antenna up on 40. I can have a tuner right at the base of the
antenna OR I can just use a balun at the base of the antenna
Rick,
It "all depends" on what you did not communicate.
Is the vertical resonant? What frequency? I assume not resonant if a
remote tuner might be required.
If the SWR is high, then the loss in the RG-58 can be significant if a
tuner is not used at that base of the vertical. The loss depends
Hello Rick,
What you consider efficient. What amount of loss are you willing to tolerate?
If you give me the particulars on the installation I can run a model and stick
it into SimSmith and get an answer for you if you like.
Myron WV0H
Printed on Recycled Data
From: rick jones via Elecraft
In terms of efficiency, is there a substantial difference between having a
remote tuner at the feedpoint of a vertical vs having a balun at the feedpoint
and the tuner in the rig? Assume a less then 50 ft run of RG58 and at least 4
counterpoise being used in a portable situation with a
ill have them. They might make good target practice subjects. Buyer
> beware.
>
> K1WHS
>
> - Original Message -
> From: "Bob McGraw K4TAX" <rmcg...@blomand.net>
> To: <wb5...@centurytel.net>; <elecraft@mailman.qth.net>
> Sent: Thursday, J
n.qth.net>
Sent: Thursday, January 14, 2016 2:47 PM
Subject: Re: [Elecraft] OT antenna question
When I updated my 2 tuners, I used some doorknob style capacitors, of
Russian source I presume, which I purchased via E-Bay. Something like 5
for $20.These were 470pf units rated
I would like to thank the numerous hams who responded to my plea for help.
The problem that was causing my SWR to rise with high power was not in
my shack. The tuner, balun, coax and open wire line were all 100%. The
trouble was at the connection of the feedline to the antenna.
The
-
From: "Bob McGraw K4TAX" <rmcg...@blomand.net>
To: "Dave Olean" <k1...@metrocast.net>; <wb5...@centurytel.net>;
<elecraft@mailman.qth.net>
Sent: Thursday, January 14, 2016 8:56 PM
Subject: Re: [Elecraft] OT antenna question
First I'd say 6
Bob,
Are silver(ed)/dipped micas (CDE etc.) the preferred type for a tuner, or is
there a superior newer technology available?
TNX/73, Al
On Wed January 13 2016 2:52:52 pm Bob McGraw K4TAX wrote:
>
> If your tuner uses disk ceramic caps, as many do, these can be heating thus
> not being able
- From: "Bob McGraw K4TAX"
<rmcg...@blomand.net>
To: <wb5...@centurytel.net>; <elecraft@mailman.qth.net>
Sent: Thursday, January 14, 2016 2:47 PM
Subject: Re: [Elecraft] OT antenna question
When I updated my 2 tuners, I used some doorknob style capacitors, of
Russia
I asked my XYL to press the key and watch the SWR meter, and to let go
when it hit 3:1. Then she ran out and waved to me on the roof, at which
point I went up the ladder and felt the bolts. Very high tech.
If I'm right that it's the bolt material, just changing to brass bolts
should work.
I meant to reply to this query earlier, but got sidetracked. What I was going
to suggest was that you look at the interfaces between stainless steel and
aluminum. They are potentially problematic, because SS and aluminum have very
different galvanic potentials, and “in the presence of an
Interesting. My SWAG was the obvious transmission line/feed point
impedance mismatch, but I would have never thought about the fasteners
being the issue.
I'll be reading up on eddy currents now and how they apply to impedance.
Is it possible that it's not actually the ferrous materials and the
This is good advice. Ceramic capacitors can have very low loss - it
depends on the dielectric used. Smaller value NPO (zero temperature
coefficient) types tend to have the lowest loss. Large value X7R, Z5U,
etc. types have very high loss and are generally unsuitable for any
high-current RF
When I updated my 2 tuners, I used some doorknob style capacitors, of
Russian source I presume, which I purchased via E-Bay. Something like 5
for $20.These were 470pf units rated at 16KV.Don't be mislead
with the voltage rating, as it the current handling ability being the
key for RF
I'm always fascinated by those which use of a 4:1 balun when 450 ohm
line is used. In most all cases, the 450 ohm line is operated at a
known high SWR. The nature of 450 ohm line {or other line such as 300
ohm or 600 ohm, etc.} is that it exhibits much lower loss when operated
at a high SWR
Generally good info snipped:
Actually at *any* length, other than multiples of one-half wavelength, there is
always some impedance transformation in a mismatched line.
On 1/13/2016 5:40 AM, Bob McGraw K4TAX wrote:
The feed-line basically reflects the impedance of the antenna from the feed
Vic,
Your antenna has a very low feedpoint impedance on 40 meters. The 30
feet of open wire line plus the 3 feet of 450 ohm is close to a quarter
wavelength on 40 meters. That feedline length should transform the low
impedance of the dipole to a higher impedance, so the choice of a 4:1
If your tuner uses disk ceramic caps, as many do, these can be heating thus not
being able to handle the RF current. They heat and cool and change value which
in turn changes tuning.
Replacing them with suitable RF current rated units is the solution.
Bob, K4TAX
Sent from my iPhone
> On
On 1/12/2016 10:57 PM, Bob McGraw K4TAX wrote:
> If your tuner uses disk ceramic caps, as many do, these can be
> heating thus not being able to handle the RF current. They heat
> and cool and change value which in turn changes tuning.
Particularly if you are using a 4:1 balun! On 40 meters
senthal 4X6GP/K2VCO
Subject: Re: [Elecraft] OT antenna question
On 1/12/2016 10:57 PM, Bob McGraw K4TAX wrote:
> If your tuner uses disk ceramic caps, as many do, these can be > heating
thus not being able to handle the RF current. They heat > and cool and
change value which
I'm having a problem which has me stumped. I'm going to describe my
complete antenna and feed system because something in it is misbehaving
and I don't know what!
My system works on all bands from 40 to 10 (or it should).
The antenna is a full-size 20m rotary dipole. It is all aluminum
; From: k2vco@gmail.com
> Date: Tue, 12 Jan 2016 23:24:12 +0200
> Subject: [Elecraft] OT antenna question
>
> I'm having a problem which has me stumped. I'm going to describe my
> complete antenna and feed system because something in it is misbehaving
> and I don't know what!
>
thal 4X6GP/K2VCO <k2vco@gmail.com>
Cc: Elecraft Reflector <elecraft@mailman.qth.net>
Sent: Tuesday, January 12, 2016 3:27 PM
Subject: Re: [Elecraft] OT antenna question
Hi Vic,
Your story does suggest trouble at very high current points. Just a list of
things below I've heard o
January 12, 2016 9:24 PM
Subject: [Elecraft] OT antenna question
I'm having a problem which has me stumped. I'm going to describe my
complete antenna and feed system because something in it is misbehaving
and I don't know what!
My system works on all bands from 40 to 10 (or it should).
The a
Hi Vic,
Your story does suggest trouble at very high current points. Just a list of
things below I've heard or seen to stir up a new idea or two. No opinion on
which if any makes any sense in your situation.
-
Insect nests in tubular spacers on open wire.
Spacers have carbon tracks.
Harlan,
I did not see any responses on the reflector, although you may have gotten
off-reflector comments.
For best results you should have the wire spaced a bit from the supporting
stucture - while it will likely work stapled to the eaves, it will likely
change tuning on you as the weather
Harlan,
Loops tend to couple well to other things within the loop. One problem you may
experience running a loop around the eves of your house will be that you're
antenna will pick up any noise sources within the house very well, and will
couple very well to electronics in the house ... i.e.
I'm sure there is a wealth of info here on the reflector. I am
planning on putting up a loop antenna around the eves of my house. I
am running the K2 without external amplifier. Two questions:
1. Do I need to run the antenna wire using insulators, or can I just
use insulated staples and staple
49 matches
Mail list logo
