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Slightly OT: non-resonant wires

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Lynn W. Taylor, WB6UUT

Slightly OT: non-resonant wires

Only a bit off-topic, since I have a KX3 w/tuner and a 9:1 balun to go
with it.

I know how to trim a resonant antenna to the correct final length. I
also understand why truly "random" wires don't necessarily work.

The recent post about shipboard operations near Antarctica said they're
using a 53' wire.

How do you guys measure an antenna like this? I assume it can be a few
inches off, but....

73 -- Lynn
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N1EU

Re: Slightly OT: non-resonant wires

I think the only important measurement is that it avoids being near a half
wavelength on any bands. Are there really "magic" lengths to be used with
9:1 xfmr into a tuner? I'm skeptical.

73, Barry N1EU

On Tue, Feb 9, 2016 at 1:50 PM, Lynn W. Taylor, WB6UUT <
[hidden email]> wrote:

> Only a bit off-topic, since I have a KX3 w/tuner and a 9:1 balun to go
> with it.
>
> I know how to trim a resonant antenna to the correct final length. I also
> understand why truly "random" wires don't necessarily work.
>
> The recent post about shipboard operations near Antarctica said they're
> using a 53' wire.
>
> How do you guys measure an antenna like this? I assume it can be a few
> inches off, but....
>
> 73 -- Lynn
> ______________________________________________________________
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Lynn W. Taylor, WB6UUT

Re: Slightly OT: non-resonant wires

I don't believe there are magic lengths.

There are however lengths that are decidely non-magical, and if you want
something that works on 40, 30, 20, 17, 15, 12 and 10, there are many
lengths that are non-magical.

That's why I did not ask "what is a good length?" There is a pretty
good reference here: http://udel.edu/~mm/ham/randomWire/

Short of buying a 100 foot tape (or a longer one), what methods do
people use to reasonably accurately measure 53 feet (or 72 feet, or 136
feet)?

Thanks -- Lynn

On 2/9/2016 11:06 AM, Barry N1EU wrote:

> I think the only important measurement is that it avoids being near a half
> wavelength on any bands. Are there really "magic" lengths to be used with
> 9:1 xfmr into a tuner? I'm skeptical.
>
> 73, Barry N1EU
>
> On Tue, Feb 9, 2016 at 1:50 PM, Lynn W. Taylor, WB6UUT <
> [hidden email]> wrote:
>
>> Only a bit off-topic, since I have a KX3 w/tuner and a 9:1 balun to go
>> with it.
>>
>> I know how to trim a resonant antenna to the correct final length. I also
>> understand why truly "random" wires don't necessarily work.
>>
>> The recent post about shipboard operations near Antarctica said they're
>> using a 53' wire.
>>
>> How do you guys measure an antenna like this? I assume it can be a few
>> inches off, but....
>>
>> 73 -- Lynn
>>

Bob McGraw - K4TAX

Re: Slightly OT: non-resonant wires

In reply to this post by N1EU

Start with a sailboat sitting in salt water with the electrical system
and masts bonded and tied to suitable grounding plates on the hull.
This is all normal for most shipboard installations. A random length
of wire can be matched to effectively transfer RF from the transmitter.
Precise length measurements are not necessary. Keep ground loss and
other component loss to a minimum and one has a rather decent antenna.
Thus one uses an insulated back stay on the vessel.

73
Bob, K4TAX

On 2/9/2016 1:06 PM, Barry N1EU wrote:

> I think the only important measurement is that it avoids being near a half
> wavelength on any bands. Are there really "magic" lengths to be used with
> 9:1 xfmr into a tuner? I'm skeptical.
>
> 73, Barry N1EU
>
> On Tue, Feb 9, 2016 at 1:50 PM, Lynn W. Taylor, WB6UUT <
> [hidden email]> wrote:
>
>> >Only a bit off-topic, since I have a KX3 w/tuner and a 9:1 balun to go
>> >with it.
>> >
>> >I know how to trim a resonant antenna to the correct final length. I also
>> >understand why truly "random" wires don't necessarily work.
>> >
>> >The recent post about shipboard operations near Antarctica said they're
>> >using a 53' wire.
>> >
>> >How do you guys measure an antenna like this? I assume it can be a few
>> >inches off, but....
>> >
>> >73 -- Lynn

Heinz Baertschi

Re: Slightly OT: non-resonant wires

In reply to this post by N1EU

The matching range of the KX3ATU is specified as "typ. 20:1".
The ATU has a switchable L/C network, so I understand this as 10:1 up and down, or in other words the KXAT3 matches loads in the range of 5 to 500 ohm?

73, Heinz HB9BCB

> Am 09.02.2016 um 20:06 schrieb Barry N1EU <[hidden email]>:
>
> I think the only important measurement is that it avoids being near a half
> wavelength on any bands. Are there really "magic" lengths to be used with
> 9:1 xfmr into a tuner? I'm skeptical.
>
> 73, Barry N1EU
>
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N1EU

Re: Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

A 53ft end-fed wire has a radiation pattern that varies all over the map as
you go up in frequency above 10MHz.

For 40-10M, I much prefer a 44ft center-fed doublet which has a broadside
pattern on all bands.

Barry N1EU

On Tue, Feb 9, 2016 at 2:38 PM, Lynn W. Taylor, WB6UUT <
[hidden email]> wrote:

> I don't believe there are magic lengths.
>
> There are however lengths that are decidely non-magical, and if you want
> something that works on 40, 30, 20, 17, 15, 12 and 10, there are many
> lengths that are non-magical.
>
> That's why I did not ask "what is a good length?" There is a pretty good
> reference here: http://udel.edu/~mm/ham/randomWire/
>
> Short of buying a 100 foot tape (or a longer one), what methods do people
> use to reasonably accurately measure 53 feet (or 72 feet, or 136 feet)?
>
> Thanks -- Lynn
>
>
> On 2/9/2016 11:06 AM, Barry N1EU wrote:
>
>> I think the only important measurement is that it avoids being near a half
>> wavelength on any bands. Are there really "magic" lengths to be used with
>> 9:1 xfmr into a tuner? I'm skeptical.
>>
>> 73, Barry N1EU
>>
>> On Tue, Feb 9, 2016 at 1:50 PM, Lynn W. Taylor, WB6UUT <
>> [hidden email]> wrote:
>>
>> Only a bit off-topic, since I have a KX3 w/tuner and a 9:1 balun to go
>>> with it.
>>>
>>> I know how to trim a resonant antenna to the correct final length. I also
>>> understand why truly "random" wires don't necessarily work.
>>>
>>> The recent post about shipboard operations near Antarctica said they're
>>> using a 53' wire.
>>>
>>> How do you guys measure an antenna like this? I assume it can be a few
>>> inches off, but....
>>>
>>> 73 -- Lynn
>>>
>>>
> ______________________________________________________________
> Elecraft mailing list
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>
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>

Bob McGraw - K4TAX

Re: Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

I use a BOSCH laser tape obtained from the local hardware supply store.
It measures to 250 ft, +/- 1/16". The only challenge is to estimate
the wire sag in measuring a long length of wire. The laser is always
measuring straight line. For shorter lengths, I stretch the wire tight
on the floor of the shop or laying over reasonably level ground and
shoot the laser along side.

In general hams will construct the antenna and then trim the length {add
or subtract length} to get the SWR value to 1:1 or such.

73
Bob, K4TAX

On 2/9/2016 1:38 PM, Lynn W. Taylor, WB6UUT wrote:
>
> Short of buying a 100 foot tape (or a longer one), what methods do
> people use to reasonably accurately measure 53 feet (or 72 feet, or
> 136 feet)?
>

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Lynn W. Taylor, WB6UUT

Re: Slightly OT: non-resonant wires

Which works great if the antenna is supposed to be resonant on one or
more bands.

On 2/9/2016 12:22 PM, Bob McGraw K4TAX wrote:
> In general hams will construct the antenna and then trim the length
> {add or subtract length} to get the SWR value to 1:1 or such.

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Lynn W. Taylor, WB6UUT

Re: Slightly OT: non-resonant wires

In reply to this post by N1EU

I asked the best way to measure a piece of wire 53' long.

On 2/9/2016 11:58 AM, Barry N1EU wrote:
> A 53ft end-fed wire has a radiation pattern that varies all over the map as
> you go up in frequency above 10MHz.

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Lynn W. Taylor, WB6UUT

Re: Slightly OT: non-resonant wires

In reply to this post by Heinz Baertschi

I shouldn't have said anything about antennas, or how I was feeding it.

How would you measure a string 53 feet long?

On 2/9/2016 11:56 AM, Heinz Bärtschi wrote:
> The matching range of the KX3ATU is specified as "typ. 20:1".
>

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k6dgw

Re: Slightly OT: non-resonant wires

In reply to this post by Bob McGraw - K4TAX

http://www.engineeringtoolbox.com/cable-loads-d_1816.html

A wire supported at the ends and loaded uniformly only by its own weight
will form a catenary, and mid-span sag is a function of mid-span
tension. Zero sag = infinite tension. Unfortunately, center-fed
dipoles are not uniformly loaded.

Just lay the wire out on the ground in a straight-ish line and measure
it. I use a 50' steel tape. Lots of things will affect its ultimate
electrical length when installed, you'll need to prune it some anyway.
I just fold the ends back on the wire until I've got the right length
and then cut it and belay it to the insulator(s).

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

On 2/9/2016 12:22 PM, Bob McGraw K4TAX wrote:

> The only challenge is to estimate
> the wire sag in measuring a long length of wire.
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Don Wilhelm-4

Re: Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

Lynn,

It depends on what kind of measuring sticks you have.

If you have a 100 foot tape measure, just pull out 53 feet and match the
wire to that length - that is the way I do it.
If you only have a 50 foot tape, measure 25feet, 6 inches and double it
back on itself.
If you have only a 25 foot tape, measure 18 inches from the end, put the
end of the 25 foot tape at that point and measure out the remaining 25
feet, then double it back on itself.

73,
Don W3FPR

On 2/9/2016 4:12 PM, Lynn W. Taylor, WB6UUT wrote:
> I shouldn't have said anything about antennas, or how I was feeding it.
>
> How would you measure a string 53 feet long?

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Charlie T, K3ICH

Re: Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

Measure (accurately) the length of your foot,
preferably both of them if they're different, then
walk putting one foot directly in front of, and
touching the one behind it with the wire laying
along the ground under your feet.
Multiply the number of steps times the length of
your foot (or feet if necessary).

This is very similar to how to count the number of
cows in a field.
You simply count the legs and divide by four.

73, Charlie k3ICH

-----Original Message-----
From: Elecraft
[mailto:[hidden email]] On
Behalf Of Lynn W. Taylor, WB6UUT
Sent: Tuesday, February 09, 2016 2:38 PM
To: [hidden email]
Subject: Re: [Elecraft] Slightly OT: non-resonant
wires

I don't believe there are magic lengths.

There are however lengths that are decidely
non-magical, and if you want something that works
on 40, 30, 20, 17, 15, 12 and 10, there are many
lengths that are non-magical.

That's why I did not ask "what is a good length?"
There is a pretty good reference here:
http://udel.edu/~mm/ham/randomWire/

Short of buying a 100 foot tape (or a longer one),
what methods do people use to reasonably
accurately measure 53 feet (or 72 feet, or 136
feet)?

Thanks -- Lynn

On 2/9/2016 11:06 AM, Barry N1EU wrote:
> I think the only important measurement is that
it avoids being near a
> half wavelength on any bands. Are there really
"magic" lengths to be
> used with
> 9:1 xfmr into a tuner? I'm skeptical.
>
> 73, Barry N1EU
>
> On Tue, Feb 9, 2016 at 1:50 PM, Lynn W. Taylor,
WB6UUT <
> [hidden email]> wrote:
>
>> Only a bit off-topic, since I have a KX3
w/tuner and a 9:1 balun to
>> go with it.
>>
>> I know how to trim a resonant antenna to the
correct final length. I
>> also understand why truly "random" wires don't
necessarily work.
>>
>> The recent post about shipboard operations near
Antarctica said
>> they're using a 53' wire.
>>
>> How do you guys measure an antenna like this?
I assume it can be a
>> few inches off, but....
>>
>> 73 -- Lynn
>>

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Bill Frantz

Re: Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

Well, a 100 foot tape isn't too expensive. Companies dealing in
survey gear, such as Inner Mountain Outfitters
<http://www.innermountainoutfitters.com/keson-survey-tapes/>
carry ones graduated in feet and 1/10s on one side plus meters
on the other side. Perfect for Antenna work (and cave surveying).

73 Bill AE6JV

On 2/9/16 at 11:38 AM, [hidden email] (Lynn W.
Taylor, WB6UUT) wrote:

>Short of buying a 100 foot tape (or a longer one), what methods
>do people use to reasonably accurately measure 53 feet (or 72
>feet, or 136 feet)?

-----------------------------------------------------------------------
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cheng076

Slightly OT: non-resonant wires

In reply to this post by Lynn W. Taylor, WB6UUT

There is/was quite a long discussion and lots of experimentation with 9:1 unun and random wire lengths on the pQRP group in the last month or so. Check it out.
PJH, N7PXY
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