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

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wayne burdick

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

Administrator

Jim,

Like I implied in my posting, portable operation is often more about convenience than signal strength.

Your estimate of around 7 dB sounds reasonable. That's about 1.5 S-units, to use the vernacular. When a band is open, this loss still allows a lot of contacts to be made.

Example: A couple of months ago my son and I were doing a bit of hiking/bird watching at Redwood Shores. While Griffin stalked hooded mergansers with his camera, I quickly set up my KX3 at a picnic table. I attached the whip with a right-angle BNC, along with the 13' counterpoise wire. 20 meter CW was very active with EU contest stations, most of them probably running a KW ("or so"). I called several of them running 5 W, and worked most of them on one call.

I may have been down 7 dB from a full-size vertical, but I got through nonetheless. And I didn't have to frighten any birds away with my usual weight-tossing wild-west antenna deployment routine.

Sometimes size doesn't matter.

Wayne
N6KR

On 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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EUGENE GABRY

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

It's all about making contacts anyway you can and having fun doing it!

Gene, N9TF

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Wayne
Burdick
Sent: Friday, March 25, 2016 10:00 AM
To: [hidden email]
Cc: [hidden email]
Subject: Re: [Elecraft] Strong recommendation: MFJ 18xx-series single-band
whips for KX3, etc.

Jim,

Like I implied in my posting, portable operation is often more about
convenience than signal strength.

Your estimate of around 7 dB sounds reasonable. That's about 1.5 S-units, to
use the vernacular. When a band is open, this loss still allows a lot of
contacts to be made.

Example: A couple of months ago my son and I were doing a bit of hiking/bird
watching at Redwood Shores. While Griffin stalked hooded mergansers with his
camera, I quickly set up my KX3 at a picnic table. I attached the whip with
a right-angle BNC, along with the 13' counterpoise wire. 20 meter CW was
very active with EU contest stations, most of them probably running a KW
("or so"). I called several of them running 5 W, and worked most of them on
one call.

I may have been down 7 dB from a full-size vertical, but I got through
nonetheless. And I didn't have to frighten any birds away with my usual
weight-tossing wild-west antenna deployment routine.

Sometimes size doesn't matter.

Wayne
N6KR

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

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

In reply to this post by wayne burdick

Just a minor point. Raising the counterpoise a foot or more above ground rather than just throwing it on the ground will have the effect of reducing ground losses and getting more signal radiated. So rather than just toss the counterpoise wire on the ground, it’s a good thing to keep it elevated — run it from where you have it connected (e.g., table top) out to a bush, a branch, to a fiberglass driveway marker stuck in the ground, whatever’s available. I carry a piece of small para-cord so I can tie the winder that holds my radial wire off to something. If you’re inside on a second floor, it may not matter much, but at a typical field site with lousy soil conductivity it can.

A single elevated radial will also cause a very slight distortion in the usual uniform radiation pattern with max response in the direction of the radial. Two elevated radial wires (at about 180 deg) give you the more usual non-directional pattern.

Grant NQ5T
K3 #2091, KX3 #8342

> On Mar 25, 2016, at 10:00 AM, Wayne Burdick <[hidden email]> wrote:
>
> Jim,
>
> Like I implied in my posting, portable operation is often more about convenience than signal strength.
>
> Your estimate of around 7 dB sounds reasonable. That's about 1.5 S-units, to use the vernacular. When a band is open, this loss still allows a lot of contacts to be made.
>
> Example: A couple of months ago my son and I were doing a bit of hiking/bird watching at Redwood Shores. While Griffin stalked hooded mergansers with his camera, I quickly set up my KX3 at a picnic table. I attached the whip with a right-angle BNC, along with the 13' counterpoise wire. 20 meter CW was very active with EU contest stations, most of them probably running a KW ("or so"). I called several of them running 5 W, and worked most of them on one call.
>
> I may have been down 7 dB from a full-size vertical, but I got through nonetheless. And I didn't have to frighten any birds away with my usual weight-tossing wild-west antenna deployment routine.
>
> Sometimes size doesn't matter.
>
> Wayne
> N6KR
>
>

Jim Brown-10

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

In reply to this post by wayne burdick

Yes, any antenna that's deployed beats one that isn't. :) But a #22
wire taped to a telescoping fiberglass pole can easily be wedged between
the seat and the top of a typical picnic table, and another #22 laid on
the ground. There's a photo on my qrz.com page of me doing exactly that
from a suburban Chicago park c.a. 2004. You'll recognize the radio.

73, Jim K9YC

On Fri,3/25/2016 8:00 AM, Wayne Burdick wrote:
> And I didn't have to frighten any birds away with my usual weight-tossing wild-west antenna deployment routine.

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JE0LFI

Re: PX3 BETA Firmware 1.42 Now Available

In reply to this post by EUGENE GABRY

Hi Paul / N6HZ

I’ve downloaded the beta version 1.42.

And I tried to install the beta version, but the PX3 will become off.

I tried to install the current version, the PX3 does not turn off.

Best regard,

Nakamura / JE0LFI
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Jim Brown-10

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

In reply to this post by Grant Youngman

I'm quoting your entire message because it's exactly right on all counts.

73, Jim K9YC

On Fri,3/25/2016 8:44 AM, GRANT YOUNGMAN wrote:
> Raising the counterpoise a foot or more above ground rather than just throwing it on the ground will have the effect of reducing ground losses and getting more signal radiated. So rather than just toss the counterpoise wire on the ground, it’s a good thing to keep it elevated — run it from where you have it connected (e.g., table top) out to a bush, a branch, to a fiberglass driveway marker stuck in the ground, whatever’s available. I carry a piece of small para-cord so I can tie the winder that holds my radial wire off to something. If you’re inside on a second floor, it may not matter much, but at a typical field site with lousy soil conductivity it can.
>
> A single elevated radial will also cause a very slight distortion in the usual uniform radiation pattern with max response in the direction of the radial. Two elevated radial wires (at about 180 deg) give you the more usual non-directional pattern.

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wayne burdick

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

Administrator

In reply to this post by Jim Brown-10

Jim Brown <[hidden email]> wrote:

> A #22 wire taped to a telescoping fiberglass pole can easily be wedged between the seat and the top of a typical picnic table...

True enough, but the whip, when collapsed, is a lot shorter.

Wayne
N6KR

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Jim Brown-10

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

On Fri,3/25/2016 9:31 AM, Wayne Burdick wrote:
> Jim Brown<[hidden email]> wrote:
>
>> >A #22 wire taped to a telescoping fiberglass pole can easily be wedged between the seat and the top of a typical picnic table...
> True enough, but the whip, when collapsed, is a lot shorter.

No doubt, and the whip is less weight to carry. That's part of the cost
of 7+ dB. All of life is a series of compromises, and when we're lucky,
we get to choose. :) To me, they're all tools in the kit.

But I can testify that from my experience working QRP in major DX
contests, a few dB can be the difference between making a QSO or not,
mostly based on the noise level at the other end. And 7+ dB is a LOT.

73, Jim K9YC
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wayne burdick

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

Administrator

> But I can testify that from my experience working QRP in major DX contests, a few dB can be the difference between making a QSO or not, mostly based on the noise level at the other end. And 7+ dB is a LOT.

That's true. But when I'm out hiking, doing quick deployments, I'm willing to accept -7 dB. Band not open enough? Enjoy the scenery.

Wayne
N6KR

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Edward R Cole

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

In reply to this post by wayne burdick

Since folks are talking adding a top hat or base loading coil, why
not just extend the length of the vertical to a full 1/4
wavelength? 1/4WL = 248/50.1 MHz = 4.95 feet (59, 3/8-inch).

Connect a small alligator clip to a 11-inch piece of hookup wire and
suspend the wire with a piece of cord to "something", OR uses heavier
stiff wire that will self-support.

Now you have a resonant 1/4 wave vertical.

OR buy a 5/8 wave base-loaded 2m mobile whip - loads on 50-MHz very
nicely. That's an old trick for dual-band 6m/2m use. Try brands
like Larsen or Maxrad.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Charlie T, K3ICH

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

OR buy a 5/8 wave base-loaded 2m mobile whip -
loads on 50-MHz very nicely. That's an old trick
for dual-band 6m/2m use. Try brands like Larsen
or Maxrad.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

This only works for a 5/8 wave 2 M antenna where
the base inductor (It's NOT a * loading coil)
isn't tapped and grounded at one end.
In other words, if there is a single connection to
the antenna, this will work.
If there's a ground connection such that the
inductor is tapped up the coil it will not
function on 50 MHz.
The Larson LM series will work, but ones designed
for the Motorola (NMO) base will not.

73, Charlie k3ICH

* A 5/8 wave antenna presents roughly 50 Ohms
resistive and some level of capacitive (-J)
reactance.
In order to match this impedance, a series
inductor is required to cancel the capacitive
reactance,
So technically, it is not a "loading" which would
be designed to make up for the fact that an
antenna is too short for a ¼ wave resonance.

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Bill Frantz

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

I had this problem in spades finding an antenna to use on my
Miata with a Yeasu FTM-10R, which does 2M and 70Ccm along with
AM and FM broadcast. The FTM-10R manual says, “NOTE: An
antenna designed with a matching device that forms a low DC
resistance to ground may have poor recep on on the AM
Page 2
broadcast band.”

I finally parked the car outside our local Ham Radio Outlet and
took antenna after antenna out to try them. I ended up with a
Larson NMO-2/70 SH antenna which would receive AM and work on
all the rest of the bands. In addition, it is quite small and
doesn’t overwhelm the car.

73 Bill AE6JV

On 3/25/16 at 2:27 PM, [hidden email] (Charlie T, K3ICH) wrote:

>
>
>
>
>OR buy a 5/8 wave base-loaded 2m mobile whip -
>loads on 50-MHz very nicely. That's an old trick
>for dual-band 6m/2m use. Try brands like Larsen
>or Maxrad.
>
>73, Ed - KL7UW
>http://www.kl7uw.com
>"Kits made by KL7UW"
>Dubus Mag business:
>[hidden email]
>
>
>This only works for a 5/8 wave 2 M antenna where
>the base inductor (It's NOT a * loading coil)
>isn't tapped and grounded at one end. In other words, if
>there is a single connection to
>the antenna, this will work.
>If there's a ground connection such that the
>inductor is tapped up the coil it will not
>function on 50 MHz.
>The Larson LM series will work, but ones designed
>for the Motorola (NMO) base will not.
>73, Charlie k3ICH
>
>* A 5/8 wave antenna presents roughly 50 Ohms
>resistive and some level of capacitive (-J)
>reactance.
>In order to match this impedance, a series
>inductor is required to cancel the capacitive
>reactance, So technically, it is not a "loading" which would
>be designed to make up for the fact that an
>antenna is too short for a ¼ wave resonance.
>

-----------------------------------------------------------------------
Bill Frantz | Privacy is dead, get over | Periwinkle
(408)356-8506 | it. | 16345
Englewood Ave
www.pwpconsult.com | - Scott McNealy | Los Gatos,
CA 95032

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N1EU

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

In reply to this post by wayne burdick

Probably a dumb question, but any suggestions on how to connect
counterpoise wires using the MFJ-1820T? The loaded whip terminates in a
male BNC, which I assume is intended to connect directly to the KX3 antenna
jack. It's not obvious to me how to add counterpoise wires???

Thanks & 73,
Barry N1EU

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
>
>
> ______________________________________________________________
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>

Grant Youngman

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

I think some people mount them under one of the thumb screws — but it seems to me a lot simpler to just use a large enough alligator (or blunt nosed) style clip on the end of the radial wire. Clip it right to the metal shell of the male BNC.

Grant NQ5T
K3 #2091, KX3 #8342

> On Mar 29, 2016, at 7:14 AM, Barry N1EU <[hidden email]> wrote:
>
> Probably a dumb question, but any suggestions on how to connect
> counterpoise wires using the MFJ-1820T? The loaded whip terminates in a
> male BNC, which I assume is intended to connect directly to the KX3 antenna
> jack. It's not obvious to me how to add counterpoise wires???

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wayne burdick

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

Administrator

In reply to this post by N1EU

Use one of the KX3's thumbscrews. We relieved the paint on the chassis at these points so you can use them for counterpoise wires or ground.

Wayne
N6KR

On Mar 29, 2016, at 5:14 AM, "Barry N1EU [hidden email] [KX3]" <[hidden email]> wrote:

>
> Probably a dumb question, but any suggestions on how to connect counterpoise wires using the MFJ-1820T? The loaded whip terminates in a male BNC, which I assume is intended to connect directly to the KX3 antenna jack. It's not obvious to me how to add counterpoise wires???
>
> Thanks & 73,
> Barry N1EU
>
> 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
>
>
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Bruce Nourish

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

I'm always terrified of losing the thumbscrew in the grass. I wish MFJ made
these with a built-in right angle and a binding post, or even just a bolt
and a wing nut, at the base.

On Tue, Mar 29, 2016 at 8:21 AM Wayne Burdick <[hidden email]> wrote:

> Use one of the KX3's thumbscrews. We relieved the paint on the chassis at
> these points so you can use them for counterpoise wires or ground.
>
> Wayne
> N6KR
>
>
> On Mar 29, 2016, at 5:14 AM, "Barry N1EU [hidden email] [KX3]" <
> [hidden email]> wrote:
>
> >
> > Probably a dumb question, but any suggestions on how to connect
> counterpoise wires using the MFJ-1820T? The loaded whip terminates in a
> male BNC, which I assume is intended to connect directly to the KX3 antenna
> jack. It's not obvious to me how to add counterpoise wires???
> >
> > Thanks & 73,
> > Barry N1EU
> >
> > 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
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> >
> >
> > __._,_.___
> > Posted by: Barry N1EU <[hidden email]>
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> • Reply to group •
> Start a New Topic • Messages in this topic (2)
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> >
> >
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Jim Brown-10

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

On Tue,3/29/2016 8:28 AM, Bruce Nourish wrote:
> I'm always terrified of losing the thumbscrew in the grass.

Easily solved. Method One: Put spade lugs on one end of the wire(s) that
you rig for counterpoise, loosen the thumb screw, and slide them under.

Method Two: Put a spade lug on a short piece of wire, slide it under the
spade lug, put a single Power Pole on the other end. Then add Power
Poles to one end of the counterpoise wires.

I use method two. In the shack, it's used to bond the KX3 to the rest of
my gear. In the field, it's easy to rig for a counterpoise.

I also carry a BNC to Pomona (dual banana) adapter, which makes it easy
to rig wires to the KX3.

73, Jim K9YC
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wayne burdick

Attaching a whip to the KX3, HT-style or table-top (right angle)

Administrator

In reply to this post by wayne burdick

Hi Gerry,

If I'm using the rig HT-style (/PM, or pedestrian mobile), I just connect the whip directly. The KX3's BNC connector is rigidly attached to the right side panel, with a D-shaped bushing so it can't rotate, and a flexible wire from the BNC's hot lead to the PCB. So you won't hurt anything by doing this. Any 48" long telescoping whip with a base loading coil and BNC will work, though as I mentioned, I'm partial to the MFJ 18xxT series.

For picnic-table-syle operation, I've been using the whip with a tiny home-made tripod. It has two female BNCs: one at the top for the whip, the other at the bottom at a right angle so it can attach directly to the radio. The radio connection can use either a double-male BNC adapter or a length of coax. The height is adjustable to match the height of the BNC on the radio.

The tripod has three legs that fold up and out of the way, resulting in a unit that's less than 6" long and 1" in diameter. Weights only a few ounces.

If anyone besides me is interested in the tripod, maybe we'll make it into an Elecraft product :)

73,
Wayne
N6KR

Gerry leary <[hidden email]> wrote:

> How do you support the whip when you connected to the radio?

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km4ltv

Re: Attaching a whip to the KX3, HT-style or table-top (right angle)

Wayne,

When you operate mobile, do you use some sort of magnetic mount to support the whip? Also does the metal of the vehicle take the place of a counter poise?

Kevin
KM4LTV

Sent from my iPhone. Please excuse any spelling or grammar errors.

> On Mar 29, 2016, at 9:44 PM, Wayne Burdick <[hidden email]> wrote:
>
> Hi Gerry,
>
> If I'm using the rig HT-style (/PM, or pedestrian mobile), I just connect the whip directly. The KX3's BNC connector is rigidly attached to the right side panel, with a D-shaped bushing so it can't rotate, and a flexible wire from the BNC's hot lead to the PCB. So you won't hurt anything by doing this. Any 48" long telescoping whip with a base loading coil and BNC will work, though as I mentioned, I'm partial to the MFJ 18xxT series.
>
> For picnic-table-syle operation, I've been using the whip with a tiny home-made tripod. It has two female BNCs: one at the top for the whip, the other at the bottom at a right angle so it can attach directly to the radio. The radio connection can use either a double-male BNC adapter or a length of coax. The height is adjustable to match the height of the BNC on the radio.
>
> The tripod has three legs that fold up and out of the way, resulting in a unit that's less than 6" long and 1" in diameter. Weights only a few ounces.
>
> If anyone besides me is interested in the tripod, maybe we'll make it into an Elecraft product :)
>
> 73,
> Wayne
> N6KR
>
>
> Gerry leary <[hidden email]> wrote:
>
>> How do you support the whip when you connected to the radio?
>
>
>
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Jim Brown-10

Re: Attaching a whip to the KX3, HT-style or table-top (right angle)

On Thu,3/31/2016 6:06 AM, [hidden email] wrote:
> When you operate mobile, do you use some sort of magnetic mount to support the whip? Also does the metal of the vehicle take the place of a counter poise?

I'm not Wayne, but I've studied this issue. Yes, the vehicle chassis
needs to serve as the counterpoise for a mobile antenna, but I have yet
to see a mag mount that does that effectively. VHF/UHF mag mounts are
designed to do that by means of capacitance between the mount and the
roof, but nearly all that I have seen have no contact between the coax
shield and the enclosure of the mount!

At HF, I see no practical way for any mag mount I've seen to have
anywhere near enough capacitance to a roof to work as a counterpoise at HF.

If you want to work mobile, you need to make a solid connection to the
frame, AND it needs to be a part of the frame that is not insulated from
the rest of the frame by PAINT. That isn't easy in most modern vehicles.

Two examples. With a Volvo S80 I owned about 15 years ago, I used a
license plate mount for Hamsticks. The license plate holder was
insulated from the trunk roof, and the trunk roof was insulated from the
rest of the body by the hinges, so I had to bond around both. That
worked pretty well, but I suspect there were still pieces of the body
that were insulated by paint.

Second example. My current vehicle, a 2006 Toyuota Sequoia (big SUV)
that I bought in Nov to move to CA from IL. It was winter in Chicago, so
K9IKZ let me bring it into the loading dock of his biz, and we poked
around to try to find good contact with the body. Lots of paint in the
way -- I found bolts a few inches from each other with no continuity
between them. I eventually mounted the antenna socket to the roof rack,
and found a nearby bolt that did get to the body.

That worked pretty well as an antenna, but the vehicle has really bad
susceptibility to HF RF -- at 100W on 20M, the main computer that runs
the vehicle goes into "limp home mode." I've never bothered to try to
fix it -- I was in the process of moving when I learned that (on an
isolated stretch of I-80 in the NV desert), so didn't have time to chase
it down, and because it was RF on the body that was exciting vehicle
wiring, I figured that it would have been pretty difficult to fix. :)
And my only interest in HF mobile is for long trips without the XYL,
which I no longer take after I finished moving. I've heard that other
big SUVs are far better in this regard.

73, Jim K9YC
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