Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

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Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

wayne burdick
Administrator
Hi all,

I've been using an MFJ-1820T telescoping 20-meter whip for a few months. Considering its length (48"), results have been excellent. I typically use it with the KX3 on a picnic table at 15 W (with an external battery), or hand-held at 3 to 5 W (internal battery).

During the ARRL DX contest I worked many countries in CW and RTTY modes, and have also had a number of longer QSOs on 20-meter SSB. Of course at these power levels, with an electrically short whip, good band conditions can't hurt.

I prefer a 25' or so wire-in-a-tree antenna when there's time. But when I need a quick deployment antenna that weighs very little, I pull out the 1820T. Note that you *must* use at least one counterpose wire. More than one helps, but all of the QSOs I described were made with a single 13'-long wire laid out on the ground. With no ground wire, you'll be down some 15 to 20 dB in transmit mode.

Since the 20-meter results were so good, I also bought the whips for 40, 17, 15, and 10 meters. 40 meters is a rough ride at 48", but I was still able to check into daytime SSB nets all over the west coast running 10 W. On the higher bands, results improve as you go higher in frequency. I worked a few JAs on 15 meter SSB running just 1 watt.

A traditional problem with such antennas is that the the SWR can sometimes be unexpectedly high, requiring that you micro-adjust the telescoping length and/or adjust the length of the counterpoise wire. This is completely unnecessary if you have an auto-tuner available. In particular, the KX3's ATU can quickly match any of these whips over their full target band. In a pinch the ATU can also match a given whip on adjacent bands. In the DX contest mentioned I tuned up the 20-meter whip on 17 and 15 meters as well, and made a few Q's there, despite the losses due to off-resonance operation.

These whips can handle a surprising amount of power. They're rated to 25 W, but I ran 50 W through the 20-meter version for several minutes without damaging it. Some other compact whips I've tried overheated quickly even at 10 W, including some of the Maldol models. When this happens, the SWR goes up and stays up until the coil cools down.

Caveat: Always use a full-size antenna when possible. But if you've just crested a new hill and only have a couple of minutes to see if the RF really is greener on the other side, this is an excellent choice.

73,
Wayne
N6KR


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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Tom Crayner
Wayne,

Funny you should bring this up, I just received an MFJ-1899T today. Slapped
a counterpoise on it and at 6 watts running JT9 (in New Jersey) was able to
be heard (watching PSK Reporter) all the way in CA and Alberta.  Just
worked a station in MN.

I'm not even giving the whip a fair chance... I'm sitting in a basement
with it cranked up to the floor joist over my head, nestled between 4 foot
fluorescent tubes and metal duct work. It tuned 1.2:1... counterpoise is
connected to ground thumb screw next to antenna jack.

I did groove a small piece of 2x4 for the right angle BNC connector to be
cradled on so all that weight of the telescopic whip doesn't damage the
jack...

Can't wait to take this down to the shore in a few weeks and see what it
can really do without all the disadvantages I've placed on it tonight....
:-)

Tom, W2YF


On Wed, Mar 23, 2016 at 10:12 PM, Wayne Burdick <[hidden email]> wrote:

> Hi all,
>
> I've been using an MFJ-1820T telescoping 20-meter whip for a few months.
> Considering its length (48"), results have been excellent. I typically use
> it with the KX3 on a picnic table at 15 W (with an external battery), or
> hand-held at 3 to 5 W (internal battery).
>
> During the ARRL DX contest I worked many countries in CW and RTTY modes,
> and have also had a number of longer QSOs on 20-meter SSB. Of course at
> these power levels, with an electrically short whip, good band conditions
> can't hurt.
>
> I prefer a 25' or so wire-in-a-tree antenna when there's time. But when I
> need a quick deployment antenna that weighs very little, I pull out the
> 1820T. Note that you *must* use at least one counterpose wire. More than
> one helps, but all of the QSOs I described were made with a single 13'-long
> wire laid out on the ground. With no ground wire, you'll be down some 15 to
> 20 dB in transmit mode.
>
> Since the 20-meter results were so good, I also bought the whips for 40,
> 17, 15, and 10 meters. 40 meters is a rough ride at 48", but I was still
> able to check into daytime SSB nets all over the west coast running 10 W.
> On the higher bands, results improve as you go higher in frequency. I
> worked a few JAs on 15 meter SSB running just 1 watt.
>
> A traditional problem with such antennas is that the the SWR can sometimes
> be unexpectedly high, requiring that you micro-adjust the telescoping
> length and/or adjust the length of the counterpoise wire. This is
> completely unnecessary if you have an auto-tuner available. In particular,
> the KX3's ATU can quickly match any of these whips over their full target
> band. In a pinch the ATU can also match a given whip on adjacent bands. In
> the DX contest mentioned I tuned up the 20-meter whip on 17 and 15 meters
> as well, and made a few Q's there, despite the losses due to off-resonance
> operation.
>
> These whips can handle a surprising amount of power. They're rated to 25
> W, but I ran 50 W through the 20-meter version for several minutes without
> damaging it. Some other compact whips I've tried overheated quickly even at
> 10 W, including some of the Maldol models. When this happens, the SWR goes
> up and stays up until the coil cools down.
>
> Caveat: Always use a full-size antenna when possible. But if you've just
> crested a new hill and only have a couple of minutes to see if the RF
> really is greener on the other side, this is an excellent choice.
>
> 73,
> Wayne
> N6KR
>
>
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

wayne burdick
Administrator
"Walter Underwood [hidden email] [KX3]" <[hidden email]> wrote:

> I got the whip for 17m. I figure there is not much difference between a coil at the base of the whip and a coil inside the ATU. Neither one will radiate. So get a whip for the highest band you want to use and let the ATU provide loading for lower bands.

That is not my experience. A high-Q loading coil, combined with the whip, is resonant near a given band and provides much lower loss than a whip of the same length with no coil, matched using the internal ATU. So while the ATU *can* match the whip on bands other than the design band, the farther you get from the design band, the greater the loss.

That said, a 17-meter whip is a good choice if you want to occasionally use it on 20 and 15 meters and you're willing to accept the comopromise. I'll try to put some numbers this. I have whips for all three bands for comparison.

When I operate mobile I use a 17-meter whip for this reason. A mobile whip with a larger tunable coil would work much better outside the design band, but my XYL (when she's riding in my CRV) prefers the svelte look of that skinny, single-band radiator :)

Wayne
N6KR


>
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)



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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Bill Frantz
I'm glad my XYL is happy with the Little Tarheel antenna on the
4Runner. My high point with it was driving over I40 from Barstow
and contacting 5Q4B in Denmark on 15M SSB. It was a good day and
he was working stations all over North and South America. DX at
100 KPH. (She was driving.)

73 Bill AE6JV

On 3/23/16 at 10:02 PM, [hidden email] (Wayne Burdick) wrote:

>When I operate mobile I use a 17-meter whip for this reason. A
>mobile whip with a larger tunable coil would work much better
>outside the design band, but my XYL (when she's riding in my
>CRV) prefers the svelte look of that skinny, single-band
>radiator :)

-----------------------------------------------------------------------
Bill Frantz        | Since the IBM Selectric, keyboards have gotten
408-356-8506       | steadily worse. Now we have touchscreen keyboards.
www.pwpconsult.com | Can we make something even worse?

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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

John Pitz
In reply to this post by wayne burdick
Hello All,

Please excuse the amateurishness of this question, but could you get one
of these whips for a low band such as 40M and use it on say 20M if you
don't extend it fully?  

John Pitz
KD8CIV



On Wed, 2016-03-23 at 22:02 -0700, Wayne Burdick wrote:

> "Walter Underwood [hidden email] [KX3]" <[hidden email]> wrote:
>
> > I got the whip for 17m. I figure there is not much difference between a coil at the base of the whip and a coil inside the ATU. Neither one will radiate. So get a whip for the highest band you want to use and let the ATU provide loading for lower bands.
>
> That is not my experience. A high-Q loading coil, combined with the whip, is resonant near a given band and provides much lower loss than a whip of the same length with no coil, matched using the internal ATU. So while the ATU *can* match the whip on bands other than the design band, the farther you get from the design band, the greater the loss.
>
> That said, a 17-meter whip is a good choice if you want to occasionally use it on 20 and 15 meters and you're willing to accept the comopromise. I'll try to put some numbers this. I have whips for all three bands for comparison.
>
> When I operate mobile I use a 17-meter whip for this reason. A mobile whip with a larger tunable coil would work much better outside the design band, but my XYL (when she's riding in my CRV) prefers the svelte look of that skinny, single-band radiator :)
>
> Wayne
> N6KR
>
>
> >
> >
> > wunder
> > K6WRU
> > Walter Underwood
> > CM87wj
> > http://observer.wunderwood.org/ (my blog)
>
>
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>
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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Bruce Nourish
Most of the electrical length of these physically-short whips is in the
loading coal. Adjusting the length of the 40m whip as you describe would
only move the resonance point around within the 40m band. To move the
resonance point between bands, you'd need to tap the coil. MFJ makes such a
whip; scroll to page 2 of this doc and read about the 1899T:

http://www.mfjenterprises.com/support.php?productid=MFJ-1810T

On Thu, Mar 24, 2016 at 6:55 AM John Pitz <[hidden email]> wrote:

> Hello All,
>
> Please excuse the amateurishness of this question, but could you get one
> of these whips for a low band such as 40M and use it on say 20M if you
> don't extend it fully?
>
> John Pitz
> KD8CIV
>
>
>
> On Wed, 2016-03-23 at 22:02 -0700, Wayne Burdick wrote:
>
> > "Walter Underwood [hidden email] [KX3]" <
> [hidden email]> wrote:
> >
> > > I got the whip for 17m. I figure there is not much difference between
> a coil at the base of the whip and a coil inside the ATU. Neither one will
> radiate. So get a whip for the highest band you want to use and let the ATU
> provide loading for lower bands.
> >
> > That is not my experience. A high-Q loading coil, combined with the
> whip, is resonant near a given band and provides much lower loss than a
> whip of the same length with no coil, matched using the internal ATU. So
> while the ATU *can* match the whip on bands other than the design band, the
> farther you get from the design band, the greater the loss.
> >
> > That said, a 17-meter whip is a good choice if you want to occasionally
> use it on 20 and 15 meters and you're willing to accept the comopromise.
> I'll try to put some numbers this. I have whips for all three bands for
> comparison.
> >
> > When I operate mobile I use a 17-meter whip for this reason. A mobile
> whip with a larger tunable coil would work much better outside the design
> band, but my XYL (when she's riding in my CRV) prefers the svelte look of
> that skinny, single-band radiator :)
> >
> > Wayne
> > N6KR
> >
> >
> > >
> > >
> > > wunder
> > > K6WRU
> > > Walter Underwood
> > > CM87wj
> > > http://observer.wunderwood.org/ (my blog)
> >
> >
> >
> > ______________________________________________________________
> > 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
> > Message delivered to [hidden email]
> >
> ______________________________________________________________
> Elecraft mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

lstavenhagen
In reply to this post by John Pitz
You can, but the better compromise if you can do it is the longest possible radiating element with the least amount of added inductance in the coil.

Reason being, a very short radiating element, even when tuned to resonance with a lot of coil will have, among other things, a very low radiation resistance. In the field this will have two results that will make you tear your hair out: one, an extremely narrow bandwidth, which will make adjustments to resonance extremely touchy and two a high swr even at resonance. So you may still only be able to get it to 2:1 at resonance, depending on how short your element actually is. And even so, the performance will be significantly reduced due to the low radiation resistance.

I do a lot of /p with my Buddipole and have found this through experimentation. For example, with its stock 5 1/2' whips, it's only enjoyable to deploy on 10,12 and 15. On 17 and 20, it gets really touchy to adjust and the 2:1 bandwidth just barely covers the CW portion once tuned. Also, raising the antenna on my 19' mast raises the resonance enough to really be annoying to get it setup on 20 meters.

30 and 40 meters, forget it lol....

So I ordered the longer 9' whips for mine and that all but solves the problem. on 20 meters, for example, only a few turns of each coil is needed, but the SWR at resonance is commonly 1.2:1 or even 1:1 depending on where I deploy out in the woods. It's reasonable to tune on 30 meters (and haven't tried 40 yet). On 10, 12, 15 it can go to full length and no coils are required at all. There the bandwidth is very wide with a low SWR across almost the entire 15 meter band for example.

When I really need to "boom in" somewhere with my 10 watts, I setup a resonant antenna with the long whips and just accept having to adjust the antenna when I change bands.

When I'm lazy, I just use a 100' wire inverted V centered on my 19' mast and just use the tuners in my rigs (all my K's have the antenna tuners in them). That works pretty good, especially on the higher bands, but not quite as good as resonant setups...

Anyway, just my experience since I operate /p almost 100% of the time now, out in the mountains here in northern NM. At 10,000' I'm almost a SOTA operation lol...

73,
LS
W5QD
John Pitz wrote
Hello All,

Please excuse the amateurishness of this question, but could you get one
of these whips for a low band such as 40M and use it on say 20M if you
don't extend it fully?  

John Pitz
KD8CIV
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

W8JH
This post has NOT been accepted by the mailing list yet.
In reply to this post by wayne burdick
Wayne,

I also have used a MFJ telescoping whip with my KX3 and have stolen a few good ideas to go with it.

I have the whip that can extend to 17 feet in length (MFJ-1979) so I can telescope out a quarter wave vertical for any band 6m through 20m.  To be extra lazy you can print out a chart with the lengths (and number of sections to telescope out) at this website:  http://www.kd5fx.com/FXportable/fx_portable_antenna.htm

In addition to stealing that idea I was inspired by the CrankIR antenna concept to come up with a way to telescope in/out the appropriate length of radials.  I got a 34 foot length of Davis SuperFlex wire and a cheap fly fishing reel (the bigger the better).  I pulled through a small loop of the DavisFlex at the center of the wire (17 feet) and pulled this through the center of the fly fishing reel being careful to have each of the remaining 17 foot lengths sticking out of opposite sides of the fly fishing reel.  With this arrangement I can reel in or out to two equal sized elevated radials.  I then used some shrink tubing to mark the appropriate length for each of the six bands from 6m-20m.  After the radials are set I use alligator clips to jumper the small loop sticking out of the center of the reel to the base of the vertical.

I use a jaws type clamp on mount for the MFJ-1979 whip to mount on something a couple feet off the ground (usually a short ground rod).  I then unreel the appropriate amount of radial wire for the band I wish to work and I use a couple wooden arrows from a children's bow and arrow set to stick in the ground the appropriate distance from my mount which keeps the two elevated radials at the same height as the the vertical base (a couple feet off the ground).

Just one ham's way of getting it done.  YMMV.

73,
Joe
W8JH
73,

Joe, W8JH

K3s, KPA 500, KAT 500 and  KX3 happy user.
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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

wayne burdick
Administrator
In reply to this post by lstavenhagen

On Mar 24, 2016, at 7:35 AM, lstavenhagen <[hidden email]> wrote:

> I do a lot of /p with my Buddipole and have found this through
> experimentation. For example, with its stock 5 1/2' whips, it's only
> enjoyable to deploy on 10,12 and 15. On 17 and 20, it gets really touchy to
> adjust and the 2:1 bandwidth just barely covers the CW portion once tuned.
> Also, raising the antenna on my 19' mast raises the resonance enough to
> really be annoying to get it setup on 20 meters.

Hi LS,

You may want to try an ATU. In that case, all you need to do is roughly peak the coil tap in RX mode, then let the ATU match the antenna across a full band for TX purposes. I do this all the time, with excellent results, at least with the ATUs in the K3/KX3/etc.

73,
Wayne
N6KR


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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Tom Crayner
In reply to this post by Bruce Nourish
John,

Just like Bruce said regarding the 1899...

I started at one tap position for 20M and then changed the coil tap to
another for 40M. When I wrote my original note that was my 40M testing... I
failed to mention in my earlier email. In this case the whip length itself
isn't adjusted, just the tap, and I guess to be optimal the length of
counterpoise should be as well, but I cut corners and didn't do that.

I got lazy and after getting it close enough I switched on the ATU of the
KX3 and it tuned to 1.2:1. That ATU is a great feature for use with
antennas such as these where bandwidth is going to be narrow and tuning can
be a pain without a good ATU. Cannot imagine life without one when doing
portable stuff with compromised antennas... I'd spend all day tuning up...

Tom, W2YF


On Thu, Mar 24, 2016 at 10:21 AM, Bruce Nourish <[hidden email]> wrote:

> Most of the electrical length of these physically-short whips is in the
> loading coal. Adjusting the length of the 40m whip as you describe would
> only move the resonance point around within the 40m band. To move the
> resonance point between bands, you'd need to tap the coil. MFJ makes such a
> whip; scroll to page 2 of this doc and read about the 1899T:
>
> http://www.mfjenterprises.com/support.php?productid=MFJ-1810T
>
> On Thu, Mar 24, 2016 at 6:55 AM John Pitz <[hidden email]>
> wrote:
>
> > Hello All,
> >
> > Please excuse the amateurishness of this question, but could you get one
> > of these whips for a low band such as 40M and use it on say 20M if you
> > don't extend it fully?
> >
> > John Pitz
> > KD8CIV
> >
> >
>
>
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Jim Brown-10
In reply to this post by wayne burdick
On Wed,3/23/2016 7:12 PM, Wayne Burdick wrote:
> I've been using an MFJ-1820T telescoping 20-meter whip for a few months. Considering its length (48"), results have been excellent. I typically use it with the KX3 on a picnic table at 15 W (with an external battery), or hand-held at 3 to 5 W (internal battery).

As Tom Schiller, N6BT, famously noted, EVERYTHING WORKS, sort of. He
demonstrated this by working all continents loading a lightbulb that he
fed with coax. Tom is the designer of the excellent Force 12 antennas.

I just did a quick NEC model of a 4 ft vertical with loading coil and a
single quarter-wave radial laying on the ground, and compared it with a
quarter-wave vertical (16.7 ft) with the same single radial. The model
is for poor soil, which is typical of most mountainous QTHs. The
full-size quarter-wave will be 7.4 dB louder than the shortened one.
That's equivalent to reducing a 15W signal to 3W. The difference is
slightly greater over better than average ground. The reduced efficiency
is due to the greatly reduced radiation resistance of the shortened
antenna.

Bottom line -- yes, shortened antennas work, sort of, but full-size
antennas work BETTER. If you can afford the weight of a means to support
the longer antenna (typically a telescoping fiberglass pole), it's well
worth it! And if a shorter antenna MUST be used, LONGER antenna, LESS
coil is better.

73, Jim K9YC
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Re: [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

lstavenhagen
In reply to this post by wayne burdick
Hi Wayne,
Yes, I do that too especially on the low bands like 30 on down. I have found, though, that with the long 9' whips, the bandwidth and SWR is low enough on 20 and up that I don't even need to use my tuners, especially since I'm normally down in the CW portions. On 15 and below the overall length is long enough to form a full sized dipole without the coils. I can go around the entire globe on 15 with the Buddipole at my selected /p spots I've found in my local area. One is outside of town on top of a really high hill (probably about 7100' above sea level) and another is in a state park in the Sangre De Christo mountains back behind town. The campground I deploy at there is around 10,000 feet, so with the Buddipole setup as a full length dipole, I have no trouble working the world on 10 watts if the bands are good.

And with the tuners, I can be lazy and use my 100' center-fed random wire in inverted V for everything. The only band the tuners have to hunt around on with it is 17 meters and they usually can only get down to about 1.7 SWR (there's probably a current node at the feed point at 18mhz which I could probably reduce by tweaking the wire length a little bit).

But even the tuner in the K2 can handle the wire antenna on all bands with no trouble. So I always buy tuners for all my K's....

Tnx es 73,
LS
W5QD
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Brendon Whateley
In reply to this post by Jim Brown-10
Jim,

Can you toss a capacitive hat on the top of the shorter vertical and see
what difference that makes? I've not figured out how to use the modeling
software yet!

- Brendon
KK6AYI

On Thu, Mar 24, 2016 at 11:14 AM, Jim Brown <[hidden email]>
wrote:

> On Wed,3/23/2016 7:12 PM, Wayne Burdick wrote:
>
>> I've been using an MFJ-1820T telescoping 20-meter whip for a few months.
>> Considering its length (48"), results have been excellent. I typically use
>> it with the KX3 on a picnic table at 15 W (with an external battery), or
>> hand-held at 3 to 5 W (internal battery).
>>
>
> As Tom Schiller, N6BT, famously noted, EVERYTHING WORKS, sort of. He
> demonstrated this by working all continents loading a lightbulb that he fed
> with coax. Tom is the designer of the excellent Force 12 antennas.
>
> I just did a quick NEC model of a 4 ft vertical with loading coil and a
> single quarter-wave radial laying on the ground, and compared it with a
> quarter-wave vertical (16.7 ft) with the same single radial. The model is
> for poor soil, which is typical of most mountainous QTHs. The full-size
> quarter-wave will be 7.4 dB louder than the shortened one. That's
> equivalent to reducing a 15W signal to 3W. The difference is slightly
> greater over better than average ground. The reduced efficiency is due to
> the greatly reduced radiation resistance of the shortened antenna.
>
> Bottom line -- yes, shortened antennas work, sort of, but full-size
> antennas work BETTER. If you can afford the weight of a means to support
> the longer antenna (typically a telescoping fiberglass pole), it's well
> worth it! And if a shorter antenna MUST be used, LONGER antenna, LESS coil
> is better.
>
> 73, Jim K9YC
>
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Jim Brown-10
On Thu,3/24/2016 3:15 PM, Brendon Whateley wrote:
> Jim,
>
> Can you toss a capacitive hat on the top of the shorter vertical and
> see what difference that makes? I've not figured out how to use the
> modeling software yet!

Now's a good time to learn. :)  Modeling software like NEC is a great
way to learn about antennas.

I don't have time to do a model, but almost any top-loading is better
than bottom loading.  My guess is that ONLY a cap hat won't bring a 4 ft
vertical to resonance without a loading coil, but depending on how big
the coil and hat are, it could be as much as 2-3 dB better than the coil
only.

73, Jim K9YC
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Don Wilhelm-4
In reply to this post by Brendon Whateley
Brendon,

A capacity hat can work on bringing the frequency downward, but how much
depends on the size of the capacity hat and the inductance of the
loading coil.

If you are not comfortable with modeling software, but have an antenna
analyzer, you can still experiment.  Try a capacity hat and see how far
it brings the resonant frequency down.  If it is not far enough, try a
bigger hat.

The fact that you can lower the resonant frequency does not indicate
efficiency (it only indicates the ability to properly load the transceiver).
Efficiency and lower SWR are not equal.  A 4 foot radiator is still a 4
foot radiator and will have full efficiency at about 50 MHz. Using it
with loading coil and/or top hat on lower frequencies will allow it to
be used, but will not compare with a full size vertical radiator.

73,
Don W3FPR

On 3/24/2016 6:15 PM, Brendon Whateley wrote:
> Jim,
>
> Can you toss a capacitive hat on the top of the shorter vertical and see
> what difference that makes? I've not figured out how to use the modeling
> software yet!
>
>

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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Josh Fiden
Not all 4ft radiators are equal! Top loading vs bottom loading changes the current distribution and raises radiation resistance of the vertical radiator. Top loading can substantially improve efficiency.

73
Josh W6XU

Sent from my mobile device

>
> <snip> ...A 4 foot radiator is still a 4 foot radiator and will have full efficiency at about 50 MHz. Using it with loading coil and/or top hat on lower frequencies will allow it to be used, but will not compare with a full size vertical radiator.
>
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Brendon Whateley
In reply to this post by Jim Brown-10
Jim,

Is there a suitable modeling software for the Mac? I've not had a Windows
machine in the house since XP was shiny and new...

- Brendon

On Thu, Mar 24, 2016 at 6:11 PM, Jim Brown <[hidden email]>
wrote:

> On Thu,3/24/2016 3:15 PM, Brendon Whateley wrote:
>
>> Jim,
>>
>> Can you toss a capacitive hat on the top of the shorter vertical and see
>> what difference that makes? I've not figured out how to use the modeling
>> software yet!
>>
>
> Now's a good time to learn. :)  Modeling software like NEC is a great way
> to learn about antennas.
>
> I don't have time to do a model, but almost any top-loading is better than
> bottom loading.  My guess is that ONLY a cap hat won't bring a 4 ft
> vertical to resonance without a loading coil, but depending on how big the
> coil and hat are, it could be as much as 2-3 dB better than the coil only.
>
>
> 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
> Message delivered to [hidden email]
>
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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Jim Brown-10
Don't know. I have never been able to get my feeble brain around Apple's
"super logical" UI.

73, Jim

On Thu,3/24/2016 10:01 PM, Brendon Whateley wrote:
> Jim,
>
> Is there a suitable modeling software for the Mac? I've not had a
> Windows machine in the house since XP was shiny and new.

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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Bill Frantz
In reply to this post by Brendon Whateley
The place to look for Mac ham radio stuff is <http://www.machamradio.com/>.

I have used Koc Chen's cocoaNEC
<http://www.w7ay.net/site/Applications/cocoaNEC/index.html> for
antenna modelling. It is quite usable.

[Unlike Jim, I haven't been able to recover from developing
software for Windows at work in the late 1990s. The only way I
survived was using Cygwin -- a Unix shell and environment for Windows.]

73 Bill AE6JV

On 3/24/16 at 10:01 PM, [hidden email] (Brendon Whateley) wrote:

>Is there a suitable modeling software for the Mac? I've not had a Windows
>machine in the house since XP was shiny and new...

---------------------------------------------------------------------------
Bill Frantz        | "I wish there was a knob on the TV to turn
up the
408-356-8506       | intelligence.  There's a knob called
"brightness", but
www.pwpconsult.com | it doesn't work. -- Gallagher

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Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

Brendon Whateley
Thanks for the Mac pointer and advice. Now to see if I can find enough time
to do some modeling.

I do software stuff and spend a lot of time in the "Console" -- Windows
version of that is just so clunky... shudder -- At least the mac is Unix
like so matches all the servers with run Linux. Don't forget Windows has
been training users on their version of UI for 20 odd years. It may take
more than 5 minutes to figure out Mac or Linux. But neither is too hard to
pick up. In fact, Linux has a "Redmond" mode if you really need it to look
similar.

- Brendon

On Thu, Mar 24, 2016 at 11:10 PM, Bill Frantz <[hidden email]> wrote:

> The place to look for Mac ham radio stuff is <http://www.machamradio.com/
> >.
>
> I have used Koc Chen's cocoaNEC <
> http://www.w7ay.net/site/Applications/cocoaNEC/index.html> for antenna
> modelling. It is quite usable.
>
> [Unlike Jim, I haven't been able to recover from developing software for
> Windows at work in the late 1990s. The only way I survived was using Cygwin
> -- a Unix shell and environment for Windows.]
>
> 73 Bill AE6JV
>
> On 3/24/16 at 10:01 PM, [hidden email] (Brendon Whateley) wrote:
>
> Is there a suitable modeling software for the Mac? I've not had a Windows
>> machine in the house since XP was shiny and new...
>>
>
> ---------------------------------------------------------------------------
> Bill Frantz        | "I wish there was a knob on the TV to turn up the
> 408-356-8506       | intelligence.  There's a knob called "brightness",
> but
> www.pwpconsult.com | it doesn't work. -- Gallagher
>
>
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