KXAT1 with short whip antennas?

[Martin Gillen]

Hi.

I read the manual for the KXAT1 and the advice for
antennas states that short whip antennas should only
be used in emergencies.

Text of the manual included below.

This seems strange because when I read the HFPack
yahoo group I can find lots of HAMs who are using the
KX1/KXAT1 with various HF whips attached to bicycles
with varying degrees of success.  Any HF whip
connected
to a bicycle must be a "short" whip, probably loaded.

Anyone have an opinion or personal experience who
can shed some light?

I'd like to fit the KX1 to my bike!

Martin.

Manual text:

Backpacking Verticals: The KXAT1 may improve the match
to a backpacking-style vertical. If the
antenna has a loading coil, you should first adjust it
for minimum SWR, since such antennas can be very
narrow-banded. Set the ATU menu entry to CAL mode
(bypass) for this purpose, then back to TUN
mode to further match the antenna using the KXAT1 (if
necessary).

Whip Antennas: Short whip antennas connected directly
to the KX1 may damage the antenna jack or PC
board, and so should only be used in an emergency.
They are also very poor radiators.

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[DW Harms]

Martin,

I understand that a whip attached directly to the BNC jacket of the KXAT1
could give mechanical frictions. The BNC is soldered directly onto the
KXAT1 pcb without support of the enclosure and that makes it somewhat
fragile.

Have fun on the bike and 73 from bikeland nr. 1 : Netherlands ;)

Dick/PA2DW

> Hi.
>
> I read the manual for the KXAT1 and the advice for
> antennas states that short whip antennas should only
> be used in emergencies.
>
> Text of the manual included below.
>
> This seems strange because when I read the HFPack
> yahoo group I can find lots of HAMs who are using the
> KX1/KXAT1 with various HF whips attached to bicycles
> with varying degrees of success.  Any HF whip
> connected
> to a bicycle must be a "short" whip, probably loaded.
>
> Anyone have an opinion or personal experience who
> can shed some light?
>
> I'd like to fit the KX1 to my bike!
>
> Martin.
>
> Manual text:
>
> Backpacking Verticals: The KXAT1 may improve the match
> to a backpacking-style vertical. If the
> antenna has a loading coil, you should first adjust it
> for minimum SWR, since such antennas can be very
> narrow-banded. Set the ATU menu entry to CAL mode
> (bypass) for this purpose, then back to TUN
> mode to further match the antenna using the KXAT1 (if
> necessary).
>
> Whip Antennas: Short whip antennas connected directly
> to the KX1 may damage the antenna jack or PC
> board, and so should only be used in an emergency.
> They are also very poor radiators.
>
> Send instant messages to your online friends http://uk.messenger.yahoo.com
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> Elecraft web page: http://www.elecraft.com
>

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[Ron D'Eau Claire-2]

Martin wrote:

I read the manual for the KXAT1 and the advice for
antennas states that short whip antennas should only
be used in emergencies.

Text of the manual included below.

This seems strange because when I read the HFPack
yahoo group I can find lots of HAMs who are using the
KX1/KXAT1 with various HF whips attached to bicycles
with varying degrees of success.  Any HF whip
connected
to a bicycle must be a "short" whip, probably loaded.

Anyone have an opinion or personal experience who
can shed some light?

I'd like to fit the KX1 to my bike!

Reply: --------------------------------

What the manual says is correct. Short whips are terrible radiators and they
should not be connected directly to the antenna jack, but the reason they
should not be connected directly to the antenna jack is *not* because they
are terrible radiators.

TERRIBLE RADIATOR:
Almost anything other than a very well-shielded dummy load will radiate
better than a short whip. But they do radiate a little bit. Running a couple
of watts with your KX1 you might have an effective radiated power of a few
milliwatts. Now, being "terrible" is relative. A few milliwatts can be heard
over very long distances under the right conditions, and it can be heard
over short distances at any time.

The efficiency of an antenna does *not* change linearly with it's size. At
very small sizes, a small increase in the size of an antenna can result in a
relatively big increase in radiated power. For example, making a very small
antenna twice as long doesn't double the effective radiated power, it can
make if five or 10 times better! So when you are dealing with a small
antenna, don't lose one inch of radiator more than you need to. And when
you're dealing with an end-fed antenna, the same is true of the ground. A
tiny improvement can make a huge improvement in signal strength at the other
end.

Still, a short whip is the only thing that fits some applications, such as
pedestrian or bike mobile. A lot of operators will attest to having a great
deal of fun with them in spite of their abysmal efficiency.

DON'T CONNECT TO KX1 ANTENNA JACK:
That's a mechanical issue, not a performance issue. The BNC antenna jack on
the KX1 is attached to and supported entirely by the printed circuit board.
There's no mechanical connection to the case to support the connector, so
any strain placed on the connector must be borne by the board. A stiff whip
connected directly to the jack that gets bumped could easily shear off the
corner of the pc board holding the jack. That's why it that practice is
strongly discouraged by Elecraft.

Ron AC7AC



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[Leigh L. Klotz Jr WA5ZNU]

Martin,
The Maldol 20M whip is fine with a radial 10-16ft and a 1ft or so piece
of bus wire clipped to the top with an alligator clip, at any angle.  I
worked Florida from Toronto on vacation twice with that antenna, acting
on Wayne N6KR's lead.  But on a bike you may want something better as
you havbe the opportunity (and mechanical need) to hold something more
substantial, such as a Hamstick or a CB whip. Watch the height
regulations though!  The ground will be different, especially on the low
bands.  Budd W3FF operates his Buddipole on a bike with great success
and he uses an inductor in series with the ground to the bike frame on
60M.  I have heard Budd work the south pole on it SSB!
73,
Leigh.
On Mon, 25 Apr 2005 8:20 am, Martin Gillen wrote:
> Hi.
> I read the manual for the KXAT1 and the advice for antennas states that
> short whip antennas should only be used in emergencies.
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[Martin Gillen]

Hi, Paul.

You may be right!  I didn't think about the physical
aspect of it.  For bike mobile I would be mouting a
whip behind me with coax running forward to the rig
in a front basket, I wouldn't even have considered
actually attaching a whip directly to such a tiny
radio!

Martin.

--- Paul Bruneau <[hidden email]> wrote:

> On Apr 25, 2005, at 11:18 AM, Martin Gillen wrote:
>
> > Hi.
> >
> > I read the manual for the KXAT1 and the advice for
> > antennas states that short whip antennas should
> only
> > be used in emergencies.
> >
> > Text of the manual included below.
>
> the way I read it, the manual is concerned about the
> mechanical
> connection being physically damaged by the leverage
> of a whip being
> directly connected to it. Is that how you are
> reading it too?
>
> I'd love to do some bicycle operating myself, but I
> think I would not
> want to use the radio as the only anchor for such an
> antenna.
>
> > Whip Antennas: Short whip antennas connected
> directly
> > to the KX1 may damage the antenna jack or PC
> > board, and so should only be used in an emergency.
> > They are also very poor radiators.
>
>

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[Martin Gillen]

Hi, Leigh.

Thanks for the informative reply!

I hadn't thought about the ground since that is the
bike frame!  I'll have to lookup Budd's information
and see what value of inductor to use there or how to
calculate it...

I'll also have to lookup Canadian height regulations
for a mobile antenna :)

Thanks again,
Martin.

--- "Leigh L Klotz, Jr." <[hidden email]> wrote:

> Martin,
> The Maldol 20M whip is fine with a radial 10-16ft
> and a 1ft or so piece
> of bus wire clipped to the top with an alligator
> clip, at any angle.  I
> worked Florida from Toronto on vacation twice with
> that antenna, acting
> on Wayne N6KR's lead.  But on a bike you may want
> something better as
> you havbe the opportunity (and mechanical need) to
> hold something more
> substantial, such as a Hamstick or a CB whip. Watch
> the height
> regulations though!  The ground will be different,
> especially on the low
> bands.  Budd W3FF operates his Buddipole on a bike
> with great success
> and he uses an inductor in series with the ground to
> the bike frame on
> 60M.  I have heard Budd work the south pole on it
> SSB!
> 73,
> Leigh.
> On Mon, 25 Apr 2005 8:20 am, Martin Gillen wrote:
> > Hi.
> > I read the manual for the KXAT1 and the advice for
> antennas states that
> > short whip antennas should only be used in
> emergencies.
>

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[Martin Gillen]

In-reply-to:
<[hidden email]>

Hi, Ron.

A very informative answer, thanks!  I was thinking
purely
in terms of the electrical characteristics of the
antenna
when I read the manual, not the physical, because to
me
it was obvious that a whip should not be directly
connected to the KX1.

Makes much more sense now!

Thanks,
Martin.



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[Michael Babineau]

Leigh L Klotz, Jr." <[hidden email]> wrote :

 > The Maldol 20M whip is fine with a radial 10-16ft and a 1ft or so
piece
 > of bus wire clipped to the top with an alligator clip, at any angle.  
I
 > worked Florida from Toronto on vacation twice with that antenna,
acting
 > on Wayne N6KR's lead.

Likewise, I have worked France with a similar setup from Maine, but ...
as someone else mentioned one has to be very careful to avoid damaging
the PCB as the BNC is directly mounted to the board.

Martin, for portable operations you will have much better luck with a
longer wire.
The KXAT1 was optimized for the recommended 24 to 28 ft wire and will
load
this with a decent SWR and pretty good performance on 40M / 30M / 20M
with a
reasonable ground. This will give you better and more consistent
performance than
a short loaded whip.

For bike mobile I would recommend that you try a  Hamstick. They are
cheap
and on 20M especially, performance is not too bad.

I have also had pretty good luck using a 14ft linear loaded wire
attached to a 13 ft telescopic
fishing pole for Pedestrian mobile operations with a 30ft trailing
counterpoise wire.

Michael VE3WMB

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[Aron Brown]

I also have found that the Maldol whip is capable of making contacts. What I
have done to solve the problem of possibly breaking the BNC from the board
is to use a auto window mount I bought at HRO. I attach this either by a
vice grip or clamp to the deck or table and run the coax to the KX1. Works
great. Got St Croix and England using this setup.


Aron
NN1F
Bedford, NH
FP#122
-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Michael Babineau
Sent: Tuesday, April 26, 2005 8:52 AM
To: [hidden email]
Cc: [hidden email]
Subject: Re: [Elecraft] KXAT1 with short whip antennas?

Leigh L Klotz, Jr." <[hidden email]> wrote :

 > The Maldol 20M whip is fine with a radial 10-16ft and a 1ft or so
piece
 > of bus wire clipped to the top with an alligator clip, at any angle.  
I
 > worked Florida from Toronto on vacation twice with that antenna,
acting
 > on Wayne N6KR's lead.

Likewise, I have worked France with a similar setup from Maine, but ...
as someone else mentioned one has to be very careful to avoid damaging
the PCB as the BNC is directly mounted to the board.

Martin, for portable operations you will have much better luck with a
longer wire.
The KXAT1 was optimized for the recommended 24 to 28 ft wire and will
load
this with a decent SWR and pretty good performance on 40M / 30M / 20M
with a
reasonable ground. This will give you better and more consistent
performance than
a short loaded whip.

For bike mobile I would recommend that you try a  Hamstick. They are
cheap
and on 20M especially, performance is not too bad.

I have also had pretty good luck using a 14ft linear loaded wire
attached to a 13 ft telescopic
fishing pole for Pedestrian mobile operations with a 30ft trailing
counterpoise wire.

Michael VE3WMB

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