Elecraft › [K3]

OCF antennas

Classic

List

Threaded

53 messages Options

123

Guy, K2AV

Re: OCF antennas

Well, I don't think you can blame OCF for TVI/RFI. You can blame radiating
RF for TVI/RFI. Some of the best improvements in RF antennary were
accompanied by increases in TVI/RFI, and that would include cleaning all
that common mode current off the feedline so it only radiated off the
driven element down toward the horizon like it should be. BTDT. Back in
the day of 21 mc TV IF's, just sneezing on fifteen meters would cause TVI.

If one only uses antennas that you don't have to think about, what fun
would that be? Part of the draw of ham radio is making metal stuff work
like an antenna, in spite of itself.

73, Guy

PS, who doesn't know what "mc" is?

On Sat, Mar 10, 2012 at 3:27 AM, Jim Brown <[hidden email]>wrote:

> On 3/9/2012 5:48 PM, Guy Olinger K2AV wrote:
> > OCF antennas, under miscellaneous names, have been working fine, just
> fine,
> > just about as long as radio.
>
> "Working fine" depends on your definition of "the big picture," and your
> ability to diagnose problems. The problem with OCF antennas is COMMON
> MODE FEEDLINE CURRENT, which causes the feedline to receive noise, make
> the shack hot with RF, and radiate RF to the TV and stereoand computer
> in our living room (and our neighbor's living room). Fifty years ago,
> there was relatively little man made noise to be picked up on the
> feedline of our antennas, the equipment in our living room did not have
> Pin One Problems that turned all of the wiring into receiving and
> transmitting antennas, and the equipment in our neighbors' living room
> was not full of noise generators (other than their TV set's horizontal
> flyback system).
>
> Equally important, we had not LEARNED about common mode current on
> feedlines, and its contribution to these problems. We lived in blissful
> ignorance. We called CQ, we got responses, we had fun, but we also had
> TVI! And when the electronics world changed, introducing Pin One
> Problems, digital equipment, and switching power supplies to create
> noise, COMMON MODE CURRENT on feedlines started biting us in the behind,
> WHETHER WE KNEW IT OR NOT.
>
> As Guy and I have both noted, we can get away with unbalanced antennas
> if we choke them to death, but we're going to fry chokes if we run power
> unless we use MULTIPLE chokes. And "choking them to death" means
> multiple turns around ferrite cores (multiple cores and multiple chokes
> for high power).
>
> A FAR better solution, if we can do it, is resonant antennas for each
> band, well choked. If you're limited on space that can be done with fan
> dipoles or traps or loading coils. And there is NO MAGIC to parallel
> wire feedline -- there can be just as much common mode current on
> parallel wire line as on coax if the antenna itself is unbalanced.
> Balance is determined by the entire circuit -- the antenna, the
> feedline, and the transmitter (including the tuner), not ONLY the
> feedline. That's why I object to the words "balanced feedline" -- they
> are are pure fiction.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Ian Kahn, KM4IK

Re: OCF antennas

In reply to this post by David Gilbert

Dave, I wish to disagree with you on this point. Yes, this is a
knowledge-based hobby. However, I learned enough to pass my exams and
got a wire in the trees so I could get on the air. I've spent my time
since then learning. You have the rest of your life to study and
learn. We have no clue how long this sunspot cycle and good propagation
conditions will last.

Just my two cents' worth. I'll shut up now.

--Ian

Ian Kahn, KM4IK
Roswell, GA
[hidden email]
K3 #281, P3 #688

On 3/10/2012 2:18 AM, David Gilbert wrote:

> Ham radio being a knowledge-based hobby, some people prefer to
> understand what they're doing. Apparently others don't seem to care.
>
> Dave AB7E
>
>
>
> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>> So let me say one thing I know about antennas:
>>
>> PUT SOMETHING UP AND GET ON THE AIR.
>>
>> You can get perfect up, and you can get OK up. You an argue about what
>> works better and what works worse. But when the bands are open, you
>> might be able to work DX with a cantenna under your desk. (I've heard
>> stories.)
>>
>> I used an untuned dipole with a LDG tuner to work my first (and only)
>> DXCC back in the last sunspot cycle.
>>
>> So what I'm saying is put something up FIRST and then start the arguing,
>> I mean, discussion.
>>
>> (But then again there are all sorts of aspects to the hobby and if you're
>> here to argue you can if you want.)
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Hisashi T Fujinaka

Re: OCF antennas

In reply to this post by David Gilbert

I went to MIT. I can analyze the crap out of this if I feel like it.

Or I can work DX and ragchew.

Like I said, you use the hobby for what you want and I'm a proponent of
the proverb that says, "Perfect is the enemy of the good."

On Sat, 10 Mar 2012, David Gilbert wrote:

>
> Ham radio being a knowledge-based hobby, some people prefer to
> understand what they're doing. Apparently others don't seem to care.
>
> Dave AB7E
>
>
>
> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>> So let me say one thing I know about antennas:
>>
>> PUT SOMETHING UP AND GET ON THE AIR.
>>
>> You can get perfect up, and you can get OK up. You an argue about what
>> works better and what works worse. But when the bands are open, you
>> might be able to work DX with a cantenna under your desk. (I've heard
>> stories.)
>>
>> I used an untuned dipole with a LDG tuner to work my first (and only)
>> DXCC back in the last sunspot cycle.
>>
>> So what I'm saying is put something up FIRST and then start the arguing,
>> I mean, discussion.
>>
>> (But then again there are all sorts of aspects to the hobby and if you're
>> here to argue you can if you want.)
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Hisashi T Fujinaka

Re: OCF antennas

In reply to this post by Jim Brown-10

On Sat, 10 Mar 2012, Jim Brown wrote:

> And there is NO MAGIC to parallel wire feedline

I think the advantage (not magic) is that you get less loss in ladder
line than you do through the dielectric of coax.

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bob Nielsen-2

Re: OCF antennas (OT)

In reply to this post by Hisashi T Fujinaka

That reminds me of a couple of sayings:

Good enough is perfect.

There comes a time in any project when you need to shoot the engineers and start production.

Bob N7XY

On Mar 10, 2012, at 5:10 PM, Hisashi T Fujinaka wrote:

> I went to MIT. I can analyze the crap out of this if I feel like it.
>
> Or I can work DX and ragchew.
>
> Like I said, you use the hobby for what you want and I'm a proponent of
> the proverb that says, "Perfect is the enemy of the good."
>
> On Sat, 10 Mar 2012, David Gilbert wrote:
>
>>
>> Ham radio being a knowledge-based hobby, some people prefer to
>> understand what they're doing. Apparently others don't seem to care.
>>
>> Dave AB7E
>>
>>
>>
>> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>>> So let me say one thing I know about antennas:
>>>
>>> PUT SOMETHING UP AND GET ON THE AIR.
>>>
>>> You can get perfect up, and you can get OK up. You an argue about what
>>> works better and what works worse. But when the bands are open, you
>>> might be able to work DX with a cantenna under your desk. (I've heard
>>> stories.)
>>>
>>> I used an untuned dipole with a LDG tuner to work my first (and only)
>>> DXCC back in the last sunspot cycle.
>>>
>>> So what I'm saying is put something up FIRST and then start the arguing,
>>> I mean, discussion.
>>>
>>> (But then again there are all sorts of aspects to the hobby and if you're
>>> here to argue you can if you want.)
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>
> --
> Hisashi T Fujinaka - [hidden email]
> BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

_____
N7XY DX Cluster Node - telnet to n7xy.net, port 7300

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: OCF antennas

In reply to this post by Hisashi T Fujinaka

And I went to CIT (Case Institute of Technology) - way back when -
which was back in the '60s a rival for MIT in the forefront of
engineering cutting edge technology. After suffering through "Geunter's
Green Book" which was an attempt of an author promoting and refining
his book advancing his math theories surrounding set theory, I think I
got a decent math foundation. That was back in 1959, so conditions have
changed and the focus has morphed to a software related analysis, I
remain well entrenched in the hardware approach. While I can believe
the software solution, I cannot devise a hardware parallel, and that is
my problem. I have become a "user" of software solutions which include
SDR.

73.
Don W3FPR

On 3/10/2012 8:10 PM, Hisashi T Fujinaka wrote:

> I went to MIT. I can analyze the crap out of this if I feel like it.
>
> Or I can work DX and ragchew.
>
> Like I said, you use the hobby for what you want and I'm a proponent of
> the proverb that says, "Perfect is the enemy of the good."
>
> On Sat, 10 Mar 2012, David Gilbert wrote:
>
>> Ham radio being a knowledge-based hobby, some people prefer to
>> understand what they're doing. Apparently others don't seem to care.
>>
>> Dave AB7E
>>
>>
>>
>> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>>> So let me say one thing I know about antennas:
>>>
>>> PUT SOMETHING UP AND GET ON THE AIR.
>>>
>>> You can get perfect up, and you can get OK up. You an argue about what
>>> works better and what works worse. But when the bands are open, you
>>> might be able to work DX with a cantenna under your desk. (I've heard
>>> stories.)
>>>
>>> I used an untuned dipole with a LDG tuner to work my first (and only)
>>> DXCC back in the last sunspot cycle.
>>>
>>> So what I'm saying is put something up FIRST and then start the arguing,
>>> I mean, discussion.
>>>
>>> (But then again there are all sorts of aspects to the hobby and if you're
>>> here to argue you can if you want.)
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>

Bill K9YEQ

Re: OCF antennas

In reply to this post by Hisashi T Fujinaka

Great humor, Hisashi!!!! Isn't it just so? So many years, so much
experience, but the operations matter so much more. With my KX3 I am
hauling out all my old self-made antennas, including a super flex multiband
dipole in a 35 mm camera film can. Love to play.

73,
Bill
K9YEQ

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Hisashi T Fujinaka
Sent: Saturday, March 10, 2012 7:10 PM
To: David Gilbert
Cc: [hidden email]
Subject: Re: [Elecraft] OCF antennas

I went to MIT. I can analyze the crap out of this if I feel like it.

Or I can work DX and ragchew.

Like I said, you use the hobby for what you want and I'm a proponent of the
proverb that says, "Perfect is the enemy of the good."

On Sat, 10 Mar 2012, David Gilbert wrote:

>
> Ham radio being a knowledge-based hobby, some people prefer to
> understand what they're doing. Apparently others don't seem to care.
>
> Dave AB7E
>
>
>
> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>> So let me say one thing I know about antennas:
>>
>> PUT SOMETHING UP AND GET ON THE AIR.
>>
>> You can get perfect up, and you can get OK up. You an argue about
>> what works better and what works worse. But when the bands are open,
>> you might be able to work DX with a cantenna under your desk. (I've
>> heard
>> stories.)
>>
>> I used an untuned dipole with a LDG tuner to work my first (and only)
>> DXCC back in the last sunspot cycle.
>>
>> So what I'm saying is put something up FIRST and then start the
>> arguing, I mean, discussion.
>>
>> (But then again there are all sorts of aspects to the hobby and if
>> you're here to argue you can if you want.)
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html
>

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bill K9YEQ

Re: OCF antennas

In reply to this post by Don Wilhelm-4

Don,

This explains much about your excellent approach to issues. I started in EE
and changed to Economics in the 60's. I love electronics but the theories
and dedication to such intricacies bored me to death. I love to play with
radios, learn what I actually need and leave the rest to those who do best
at the theory and studies. Building stuff is my love, including PC's with
the software.

73,
Bill
K9YEQ

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Saturday, March 10, 2012 7:40 PM
To: Hisashi T Fujinaka
Cc: [hidden email]
Subject: Re: [Elecraft] OCF antennas

And I went to CIT (Case Institute of Technology) - way back when - which was
back in the '60s a rival for MIT in the forefront of engineering cutting
edge technology. After suffering through "Geunter's Green Book" which was
an attempt of an author promoting and refining his book advancing his math
theories surrounding set theory, I think I got a decent math foundation.
That was back in 1959, so conditions have changed and the focus has morphed
to a software related analysis, I
remain well entrenched in the hardware approach. While I can believe
the software solution, I cannot devise a hardware parallel, and that is my
problem. I have become a "user" of software solutions which include SDR.

73.
Don W3FPR

On 3/10/2012 8:10 PM, Hisashi T Fujinaka wrote:

> I went to MIT. I can analyze the crap out of this if I feel like it.
>
> Or I can work DX and ragchew.
>
> Like I said, you use the hobby for what you want and I'm a proponent
> of the proverb that says, "Perfect is the enemy of the good."
>
> On Sat, 10 Mar 2012, David Gilbert wrote:
>
>> Ham radio being a knowledge-based hobby, some people prefer to
>> understand what they're doing. Apparently others don't seem to care.
>>
>> Dave AB7E
>>
>>
>>
>> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>>> So let me say one thing I know about antennas:
>>>
>>> PUT SOMETHING UP AND GET ON THE AIR.
>>>
>>> You can get perfect up, and you can get OK up. You an argue about
>>> what works better and what works worse. But when the bands are open,
>>> you might be able to work DX with a cantenna under your desk. (I've
>>> heard
>>> stories.)
>>>
>>> I used an untuned dipole with a LDG tuner to work my first (and
>>> only) DXCC back in the last sunspot cycle.
>>>
>>> So what I'm saying is put something up FIRST and then start the
>>> arguing, I mean, discussion.
>>>
>>> (But then again there are all sorts of aspects to the hobby and if
>>> you're here to argue you can if you want.)
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net Please help support this
>> email list: http://www.qsl.net/donate.html
>>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: OCF antennas

In reply to this post by Hisashi T Fujinaka

On 3/10/2012 5:14 PM, Hisashi T Fujinaka wrote:
> I think the advantage (not magic) is that you get less loss in ladder
> line than you do through the dielectric of coax.

FALSE! For all practical purposes, there is NO dielectric loss in coax
below about 500 MHz, where it just BEGINS to show up. Virtually all the
loss in any dry transmission line at HF and VHF is due to simple Ohm's
Law in the copper (including the increase in resistance due to skin
effect). It's all I squared R loss.

The advantage of open wire line is solely the result of their higher
IMPEDANCE, which means that for a given power level, the CURRENT is much
less. For the same reason, 75 ohm coax has a bit less loss than 50 ohm
coax for the same conductor size. So-called WINDOW line loses this
advantage when it gets wet, because then it DOES have dielectric loss.

BTW -- when you're analyzing these things, you must consider the heat
produced in a common mode choke when the antenna has a lot of imbalance.
An off-center fed antenna has a LOT of imbalance.

73, Jim Brown K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Hisashi T Fujinaka

Re: OCF antennas

On Sat, 10 Mar 2012, Jim Brown wrote:

> On 3/10/2012 5:14 PM, Hisashi T Fujinaka wrote:
>> I think the advantage (not magic) is that you get less loss in ladder
>> line than you do through the dielectric of coax.
>
> FALSE! For all practical purposes, there is NO dielectric loss in coax
> below about 500 MHz, where it just BEGINS to show up. Virtually all the
> loss in any dry transmission line at HF and VHF is due to simple Ohm's
> Law in the copper (including the increase in resistance due to skin
> effect). It's all I squared R loss.
>
> The advantage of open wire line is solely the result of their higher
> IMPEDANCE, which means that for a given power level, the CURRENT is much
> less. For the same reason, 75 ohm coax has a bit less loss than 50 ohm
> coax for the same conductor size. So-called WINDOW line loses this
> advantage when it gets wet, because then it DOES have dielectric loss.
>
> BTW -- when you're analyzing these things, you must consider the heat
> produced in a common mode choke when the antenna has a lot of imbalance.
> An off-center fed antenna has a LOT of imbalance.

I think you're wrong here. The high SWRs generated along the feedline
are extremely high voltages (with low currents) and there is significant
loss in the dielectric of the coax. The reason that ladder line is
better is because of the air in the dielectric. The best is the old
school ladder line with the ceramic insulators. There is very little I
squared R loss because there is very low current.

That's why people see better performance with ladder line and think it's
magic.

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Gary Ferdinand

Re: OCF antennas

>I think you're wrong here. The high SWRs generated along the feedline
>are extremely high voltages (with low currents) and there is significant
>loss in the dielectric of the coax. The reason that ladder line is
>better is because of the air in the dielectric. The best is the old
>school ladder line with the ceramic insulators. There is very little I
>squared R loss because there is very low current.
>
>That's why people see better performance with ladder line and think it's
>magic.
>

I think in today's parlance many use the term ladder line to mean any flavor
of non-coax, 2 conductor feedline. I distinguish between ladder line
(insulated twin lead with holes) and open wire line (OWL) no insulating
material other than the occasional spacer. Ceramic, plastic, etc. The OWL
does not suffer from the dreaded detuning in the rain nearly to the extent
of ladder line.

73, Gary W2CS

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: OCF antennas

In reply to this post by Hisashi T Fujinaka

On 3/10/2012 8:40 PM, Hisashi T Fujinaka wrote:
> I think you're wrong here.

The math is VERY well known. There's are a couple of excellent technical
papers about this in one of the ARRL Antenna Compendiums. Another
place to see this is on the Times data sheets for their LMR cables. Look
below the graph of loss vs frequency, where there is an equation for
loss as a function of frequency. The first term is resistive loss and
increases as the square root of frequency, the second is dielectric
loss, and increases linearly with frequency. Put the equation in a
spreadsheet and plot the curve. The square root term is skin effect.

73, Jim Brown K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: OCF antennas

In reply to this post by Gary Ferdinand

On 3/10/2012 9:05 PM, Gary Ferdinand wrote:
> The OWL does not suffer from the dreaded detuning in the rain nearly to the extent of ladder line.

Right. And while there is some change in the impedance, the primary
effect is dielectric loss due to moisture on the "solid" portions of the
window "frame."

73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

hf4me

Re: OCF antennas

In reply to this post by Ian Kahn, KM4IK

Ian, I am with you on this. jmho that starting with whatever you can put up
and for whatever reason that is all you can do at the time. If a new person
doesn't get on the air "fast" he will soon lose interest. He is interested
NOW, get him up and running and not next month or even next week if
possible, NOW.

I have also seen people with the location and resources who were excited and
able to build an optimal station as their first station and do it all at
once. Wrong thing to do. He built it, could talk anywhere and mostly
anytime and within a year he was totally bored with it and never used it
again and not long after sold it all.

Coming up through "all the pains" of not having it all at once and learning
what is better and why, trying to determine what will fit within the
restrictions they are saddled with and taking the next step, making that
better and then moving on is a great way to grow in knowledge and experience
in building antennas. Another way to gain experience is to assist in the
antenna parties in the area.

In the beginning, waiting is wrong. Just DO it, operate, and ask questions,
read, participate, join a club, BE where other hams are, LISTEN, learn,
grow, modify, add, ask for help, try other antennas.

as I said, jmho,
73, de Jim KG0KP

----- Original Message -----
From: "Ian Kahn - Ham" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 10, 2012 4:14 PM
Subject: Re: [Elecraft] OCF antennas

> Dave, I wish to disagree with you on this point. Yes, this is a
> knowledge-based hobby. However, I learned enough to pass my exams and
> got a wire in the trees so I could get on the air. I've spent my time
> since then learning. You have the rest of your life to study and
> learn. We have no clue how long this sunspot cycle and good propagation
> conditions will last.
>
> Just my two cents' worth. I'll shut up now.
>
> --Ian
>
> Ian Kahn, KM4IK
> Roswell, GA
> [hidden email]
> K3 #281, P3 #688
>
>
> On 3/10/2012 2:18 AM, David Gilbert wrote:
>> Ham radio being a knowledge-based hobby, some people prefer to
>> understand what they're doing. Apparently others don't seem to care.
>>
>> Dave AB7E
>>
>>
>>
>> On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote:
>>> So let me say one thing I know about antennas:
>>>
>>> PUT SOMETHING UP AND GET ON THE AIR.
>>>
>>> You can get perfect up, and you can get OK up. You an argue about what
>>> works better and what works worse. But when the bands are open, you
>>> might be able to work DX with a cantenna under your desk. (I've heard
>>> stories.)
>>>
>>> I used an untuned dipole with a LDG tuner to work my first (and only)
>>> DXCC back in the last sunspot cycle.
>>>
>>> So what I'm saying is put something up FIRST and then start the arguing,
>>> I mean, discussion.
>>>
>>> (But then again there are all sorts of aspects to the hobby and if
>>> you're
>>> here to argue you can if you want.)
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Hisashi T Fujinaka

Re: OCF antennas

In reply to this post by Jim Brown-10

On Sat, 10 Mar 2012, Jim Brown wrote:

> On 3/10/2012 8:40 PM, Hisashi T Fujinaka wrote:
>> I think you're wrong here.
>
> The math is VERY well known. There's are a couple of excellent technical
> papers about this in one of the ARRL Antenna Compendiums. Another
> place to see this is on the Times data sheets for their LMR cables. Look
> below the graph of loss vs frequency, where there is an equation for
> loss as a function of frequency. The first term is resistive loss and
> increases as the square root of frequency, the second is dielectric
> loss, and increases linearly with frequency. Put the equation in a
> spreadsheet and plot the curve. The square root term is skin effect.

Misapplied math is the worst of all. It's not the frequency you need to
worry about, it's the high voltage breakdown.

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Guy, K2AV

Re: OCF antennas

In reply to this post by Jim Brown-10

I have a 425 foot run of "window line", specifically Wireman #554 down to
my 160 antenna base. The "detuning" that is referred to is really a change
in the dielectric: from PE to PE+water. That changes the loss (change =
.5 dB at 1.830), but more particularly the velocity factor, which changes
the electrical length and MOVES nodes and nulls. Here are the particulars
from the line loss calculator in VK1OD's excellent collection of
calculators at http://vk1od.net/calc/tl/tllc.php .

Transmission Line Wireman 554
Code W554
Data source Wireman / N7WS
Frequency 1.830 MHz
Length 425.000 ft
Results
Zo 360.01-j1.74 Ω
Velocity Factor, VF -2 0.928, 1.161
Length 306.76 °, 0.852 λ, 129.540 m
Line Loss (matched) 0.251 dB

Transmission Line Wireman 554 wet
Code W554w
Data source N7WS
Frequency 1.830 MHz
Length 425.000 ft
Results
Zo 344.94+j3.02 Ω
Velocity Factor, VF -2 0.887, 1.271
Length 320.94 °, 0.892 λ, 129.540 m
Line Loss (matched) 0.780 dB

73, Guy.

On Sun, Mar 11, 2012 at 12:16 AM, Jim Brown <[hidden email]>wrote:

> On 3/10/2012 9:05 PM, Gary Ferdinand wrote:
> > The OWL does not suffer from the dreaded detuning in the rain nearly to
> the extent of ladder line.
>
> Right. And while there is some change in the impedance, the primary
> effect is dielectric loss due to moisture on the "solid" portions of the
> window "frame."
>
> 73, Jim K9YC
>
>

Pete Michaelis - N8TR

Re: OCF antennas-Now way off Topic

In reply to this post by Don Wilhelm-4

Don,

When I started work at NASA's Lewis Research Center in the early 60's
we often went to seminars at Case. Local legend had it that in one of
Dr Green's classes he presented a research problem that he himself
was working on and told the class that anyone solving it would be
awarded a master's degree along with his BS. Donald E Knuth
(author of the famous "The Art of Computer Programming" series of books)
was in the class and solved the problem ( and got his BS & MS in 1960).
Did that happen while you were there? I know that this is way off topic but I
have always been curious if that actually occurred.

73 Pete - N8TR

At 08:40 PM 3/10/2012, Don Wilhelm wrote:
>And I went to CIT (Case Institute of Technology) - way back when -
>which was back in the '60s a rival for MIT in the forefront of
>engineering cutting edge technology. After suffering through "Geunter's
>Green Book" which was an attempt of an author promoting and refining
>his book advancing his math theories surrounding set theory, I think I
>got a decent math foundation.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Hisashi T Fujinaka

Can anyone give me pointers to Sherwood reports?

I'm fantasizing about a new radio and I do know how much I like my K2. A
K3 would be the obvious progression. But a friend told me how much he
liked the Icom 7600 and wow are there some nice bells and whistles on
it.

I want to know tech specs. I trust that I could email Elecraft and get
much better support than any other big rig manufacturer, but have you
seen how pretty the Icom is? :) My biggest complaint about the Elecraft
is the UI and I think the Icom might have a better one (though I only
stared and drooled for a minute or so).

--
Hisashi T Fujinaka - [hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: Can anyone give me pointers to Sherwood reports?

On 3/10/2012 11:09 PM, Hisashi T Fujinaka wrote:
> But a friend told me how much he liked the Icom 7600 and wow are there some nice bells and whistles on it.

I used one on Field Day a year and a half ago. Yes, it was pretty, but
it put out enough trash to bother other stations in our group. One of my
neighbors has a 7600. He's quite active, drives an amp with it, and
makes quite a mess of phase noise and IMD when he transmits. I've heard
a similar report from a member of our club who was on a big DX trip that
had them because ICOM gave them a lot of radios for free. The K3 is MUCH
cleaner, and the RX has much better strong signal handling.

73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Scott Manthe-2

Re: Can anyone give me pointers to Sherwood reports?

In reply to this post by Hisashi T Fujinaka

Here's a link the the Sherwood specs. The IC-7600 is a decent radio, but
you can get nicely appointed K3 and you'll have a better radio in all
respects, excepting the fish-finder.

http://www.sherweng.com/table.html

Notice that the IC-7600 has the 25th ranked receiver in that table. The
Icom's menu system is easier to navigate, but I just got my K3 three
days ago, I got it up and running with just a cursory reading of the
manual. And while the K3 is complex there is a benefit in that you can
configure it to fit almost any operating style or situation.

The K3 is the best performing rig I've ever owned and while I guess it'd
be nice if it looked a little more like an FT2000/5000, there is a great
deal to be said for the styling of the K3 and the relatively small size
and light weight.

Good luck making the choice that's right for you!

73,
Scott, N9AA

On 3/11/12 3:09 AM, Hisashi T Fujinaka wrote:

> I'm fantasizing about a new radio and I do know how much I like my K2. A
> K3 would be the obvious progression. But a friend told me how much he
> liked the Icom 7600 and wow are there some nice bells and whistles on
> it.
>
> I want to know tech specs. I trust that I could email Elecraft and get
> much better support than any other big rig manufacturer, but have you
> seen how pretty the Icom is? :) My biggest complaint about the Elecraft
> is the UI and I think the Icom might have a better one (though I only
> stared and drooled for a minute or so).
>

123