Two Band Moxon/wire beam

[Charles Greene-2]

Hi,

I need some advice on a wire beam I built for field day and special
events.  It  has two fiberglass poles 22' long spaced 45' with a wire
Moxon for 40 M on the outside and a two element 20 meter beam between
the 40 meter Moxon.  It has there is little interaction between the
beams either by model of by measurement.  It is fed with two lengths
of RG-58 through 1:1 baluns at the antenna.  I designed it using
EZNEC, and optimized it for gain with an eye on F/B ratio and
impedance.  A few days ago I hosted it to 21' for a test.  The design
was for 30' which will be the actual height in operation.  I have a
chance to trim it before moving it to the special event location and
hoisting it to 30'.  Measurement vs EZNEC values for Fo and Zo are as
follows at 21' and 30'.

Fo model:  7.26 MHz at 21',  7.19 MHz at 30'
Zo model:  41.85 Ohms at 21', 35.6 Ohms at 30'
Fo actual:  6.93 MHz, at 21'
Zo actual:  50 Ohms, at 21'

Fo model: 14.2 MHz at 21', 14.235 at 30'
Zo model:  35.2 Ohms at 21', 50 ohms at 30'
Fo actual: 13.99 MHz at 21'
Zo actual:  65 Ohms. at 21'

My question is, should I reduce the length of all wires in each beam
the % that the frequency is off in each beam and leave the spacing
alone, or should I reduce everything?  It seems the frequency is off
because the model doesn't take into account all of the end effects,
but the spacing is not subject to end effects and should be left
alone.  I have no way to measure accurately measure the elevation
angle, gain and F/B ratio.

The .ez files are available for the asking to individuals.

Tnx for your time.

Chs,  W1CG

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[Stuart Rohre]

Charles,
With dual band close spaced beams, everything interacts.

You can try adjusting the wire lengths by the percentage you were off your
target frequency, or just operate them as they fell.  They will vary with
height, and there is no compelling need to have them exactly resonant in
cases like this, as long as your are getting about the beam action you want.

Your SWR actual at 21 feet seem to be OK for operations.  Or just use a
tuner to touch up the match.

Stuart
K5KVH



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[Charles Greene-2]

Stuart<

Thank you for the insight.  I calculated the % the wire lengths were
off by % the frequency was off, and I also "moved" the model up in
frequency (by shortening wire lengths in the model) by the amount it
differed from the measurement.  In other words, the actual was about
200 KHz below the model, so I moved the model up 200 KHz.  The model
was at the same height as the measurements.  Both techniques produced
results that were close.  One thing I found was to not change the
wire spacing at the ends, but just to change the length of wires
between the main supports.  I will wait until we hoist it to the
final height which I estimate to be near 30' and take some more
measurements then trim based on that.  I think we can operate with
the existing lengths as the top band edge is within the 2:1 SWR
bandwidth at 21'; it may be a little off at 30' as the resonant
frequency goes down as the height is increased, but we don't have to
operate near the top end of the band.  We have a LDG tuner, so it
should be able to tune ok.  A comment on the vertical pattern.  For
field day and special events the high angle of elevation of radiation
on 40 meters you get at a height of 30' is not a disadvantage as we
are looking for local contacts instead of DX.  About 90% of the US is
in the horizontal beamwidth from RI.  Just northern New England and
southern Florida is out side the 3 dB beamwidth.  It used to bother
me that with a dipole 1/2 of the radiated power was going toward
Europe, which really doesn't participate in field day.

Chas, W1CG

At 05:06 PM 9/26/2005, Stuart Rohre wrote:

>Charles,
>With dual band close spaced beams, everything interacts.
>
>You can try adjusting the wire lengths by the percentage you were off your
>target frequency, or just operate them as they fell.  They will vary with
>height, and there is no compelling need to have them exactly resonant in
>cases like this, as long as your are getting about the beam action you want.
>
>Your SWR actual at 21 feet seem to be OK for operations.  Or just use a
>tuner to touch up the match.
>
>Stuart
>K5KVH

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[VR2BrettGraham]

W1CG replied to K5KVH:

>Thank you for the insight.  I calculated the % the wire lengths were
>off by % the frequency was off, and I also "moved" the model up in
>frequency (by shortening wire lengths in the model) by the amount it
>differed from the measurement.  In other words, the actual was about
>200 KHz below the model, so I moved the model up 200 KHz.  The model
>was at the same height as the measurements.  Both techniques produced
>results that were close.  One thing I found was to not change the
>wire spacing at the ends, but just to change the length of wires
>between the main supports.  I will wait until we hoist it to the
>final height which I estimate to be near 30' and take some more
>measurements then trim based on that.  I think we can operate with
>the existing lengths as the top band edge is within the 2:1 SWR
>bandwidth at 21'; it may be a little off at 30' as the resonant
>frequency goes down as the height is increased, but we don't have to
>operate near the top end of the band.  We have a LDG tuner, so it
>should be able to tune ok.

I don't recall if you mentioned if you were using bare or insulated
wire.

Between the several percent that contributes & the coupling
between the elements, I think WA1X's (I believe it was) suggestion
on towertalk or somewhere a while back on how he trims
Moxons is the way to go.

With bare wire, I have done quite a bit of mucking around trying
to tune a 10m Moxon with effect of "ground" (reinforced concrete
roof top) a half wavelength up.  A decent match with reasonable
pattern I believe is probably much easier to achieve by tuning
each element separately as WA1X described.

The coupling in a Moxon rectangle is pretty intense - it is a good
idea to maintain geometry after trimming the ends, though some
sort of directivity will remain if you don't (up to a point).  I have
done all sorts of models of Moxons & all multi-band approaches
other than back-to-back look to be hard to achieve in practice
(nesting, mix with yagi elements, sleeves, etc).  Nested Moxon
reflector for the higher band & sleeve around low band driver looks
awfully interesting, but would require a _lot_ of work to trim into
submission in the real world.

GL.

73, VR2BrettGraham

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[Charles Greene-2]

Brett,

To answer your question, I am using stranded, silver plated, teflon
insulated #16 wire.  It is plenty strong.  I have a 3/16" Dacron line
between the two poles to take the strain off the wires.  This also
decreases the vertical bend and completely eliminates the horizontal
bend of the two poles.

(To review, the antenna is a 40 meter Moxon wire beam with a 2
element 20 wire meter beam inside.  There are two supports, 22' long
fiberglass poles at each end, spaced 45 '.  There are two feed lines.)

We put the antenna up today for our annual special event at for the
Harvest Faire at the Norman Bird Sanctuary in Middletown, RI for this
weekend.  Listen for us on 20 and 40.  Call is W1SYE, Newport County
Radio Club.  (See Sept QST, special events).

The antenna is about 30' high on one end and about 25' on the other,
from a portable mast to a tree.  The Fo and Zo is not much different
from what it was at 21'.  Fo is about 14.00/7.00  MHZ .  SWR is 1:1,
50 ohms on both bands per MFJ 159B.  2:1 band width is (top
frequency) 14.4 MHz and 7.25 MHz resp.  I still want to move it up to
14.2 and  7.25 MHz.  It's a very nice beam; doesn't sag much and it
is easy to erect.  The weight is about 18# which includes everything supported.

The feed lines are two lengths of double shielded RG-58 (TRF-58).  I
am going to try simultaneous operation on 40 and 20 using 20 and 40
meter bandpass filters by Array Solutions.  The 40M filter has an
insertion loss of 70 dB on 14 MHz and the 20M filter has an insertion
loss of 35 dB on 7 MHz.  I will use my K2/100 with a LDG Z-11 tuner
and the club's  Ten Tec Jupiter with its LDG tuner.   I will try my
other K2 with KAT2 in case the Jupiter overloads on receive.  I don't
know how this will work out.  Calculations say it won't work at 100
watts as there is not enough attenuation, but I will try it and
report results.  There must be some power level of the transmitters
that will work.  It would be handy for field day, but if it doesn't
work we will just have to put the second transceiver on 80 meters
using another antenna.  Or else use separate receiving antennas.  The
K2 with the KAT2 can do this;  I don't know about a K2/100 with a
KAT100.  Maybe someone can enlighten me.

Chas,  W1CG

At 06:23 PM 9/29/2005, VR2BrettGraham wrote:

>W1CG replied to K5KVH:
>
>>Thank you for the insight.  I calculated the % the wire lengths were
>>off by % the frequency was off, and I also "moved" the model up in
>>frequency (by shortening wire lengths in the model) by the amount it
>>differed from the measurement.  In other words, the actual was about
>>200 KHz below the model, so I moved the model up 200 KHz.  The model
>>was at the same height as the measurements.  Both techniques produced
>>results that were close.  One thing I found was to not change the
>>wire spacing at the ends, but just to change the length of wires
>>between the main supports.  I will wait until we hoist it to the
>>final height which I estimate to be near 30' and take some more
>>measurements then trim based on that.  I think we can operate with
>>the existing lengths as the top band edge is within the 2:1 SWR
>>bandwidth at 21'; it may be a little off at 30' as the resonant
>>frequency goes down as the height is increased, but we don't have to
>>operate near the top end of the band.  We have a LDG tuner, so it
>>should be able to tune ok.
>
>I don't recall if you mentioned if you were using bare or insulated
>wire.
>
>Between the several percent that contributes & the coupling
>between the elements, I think WA1X's (I believe it was) suggestion
>on towertalk or somewhere a while back on how he trims
>Moxons is the way to go.
>
>With bare wire, I have done quite a bit of mucking around trying
>to tune a 10m Moxon with effect of "ground" (reinforced concrete
>roof top) a half wavelength up.  A decent match with reasonable
>pattern I believe is probably much easier to achieve by tuning
>each element separately as WA1X described.
>
>The coupling in a Moxon rectangle is pretty intense - it is a good
>idea to maintain geometry after trimming the ends, though some
>sort of directivity will remain if you don't (up to a point).  I have
>done all sorts of models of Moxons & all multi-band approaches
>other than back-to-back look to be hard to achieve in practice
>(nesting, mix with yagi elements, sleeves, etc).  Nested Moxon
>reflector for the higher band & sleeve around low band driver looks
>awfully interesting, but would require a _lot_ of work to trim into
>submission in the real world.
>
>GL.
>
>73, VR2BrettGraham

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[VR2BrettGraham]

W1CG continued:

>To answer your question, I am using stranded, silver plated, teflon
>insulated #16 wire.  It is plenty strong.  I have a 3/16" Dacron line
>between the two poles to take the strain off the wires.  This also
>decreases the vertical bend and completely eliminates the horizontal
>bend of the two poles.

Presumably you know the dielectric constant of that insulation,
verified that the wire you have is in the same neighborhood &
done all your modelling based on that figure?

If so, then you can see how ground dominates & if not, then
between both ground & insulation your elements are nowhere
near where you think they are.

>(To review, the antenna is a 40 meter Moxon wire beam with a 2
>element 20 wire meter beam inside.  There are two supports, 22' long
>fiberglass poles at each end, spaced 45 '.  There are two feed lines.)
>
>We put the antenna up today for our annual special event at for the
>Harvest Faire at the Norman Bird Sanctuary in Middletown, RI for this
>weekend.  Listen for us on 20 and 40.  Call is W1SYE, Newport County
>Radio Club.  (See Sept QST, special events).
>
>The antenna is about 30' high on one end and about 25' on the other,
>from a portable mast to a tree.  The Fo and Zo is not much different
>from what it was at 21'.  Fo is about 14.00/7.00  MHZ .  SWR is 1:1,
>50 ohms on both bands per MFJ 159B.  2:1 band width is (top
>frequency) 14.4 MHz and 7.25 MHz resp.  I still want to move it up to
>14.2 and  7.25 MHz.  It's a very nice beam; doesn't sag much and it
>is easy to erect.  The weight is about 18# which includes everything
>supported.

Not many 2-element 40m beams that can be robust & only weigh
that much - not to mention less wingspan & far better F/R than a
yagi.

>The feed lines are two lengths of double shielded RG-58 (TRF-58).  I
>am going to try simultaneous operation on 40 and 20 using 20 and 40
>meter bandpass filters by Array Solutions.  The 40M filter has an
>insertion loss of 70 dB on 14 MHz and the 20M filter has an insertion
>loss of 35 dB on 7 MHz.  I will use my K2/100 with a LDG Z-11 tuner
>and the club's  Ten Tec Jupiter with its LDG tuner.   I will try my
>other K2 with KAT2 in case the Jupiter overloads on receive.  I don't
>know how this will work out.  Calculations say it won't work at 100
>watts as there is not enough attenuation, but I will try it and
>report results.  There must be some power level of the transmitters
>that will work.  It would be handy for field day, but if it doesn't
>work we will just have to put the second transceiver on 80 meters
>using another antenna.  Or else use separate receiving antennas.  The
>K2 with the KAT2 can do this;  I don't know about a K2/100 with a
>KAT100.  Maybe someone can enlighten me.

With two 400 watt rigs into two bands of a tribander simultaneously,
those filters will work - though without stubs the 2nd harmonic of
the 40m station will render some number of dozens of kilocycles on
the higher band useless.  Be sure to decouple the feeders at
the feedpoints, too.

Look at how each driver looks as you connect, disconnect or short
the far end of the feeder to the other driver.  I would imagine that your
antenna probably has the two bands' drivers electrically closer &
therefore you will have far greater interaction between the two bands
than on my tribander.  Hairpins seem to work pretty good on that,
but that means more trimming.

Anyway, I think the key point is the wire & like I said about my
bare wire Moxon, there's a bit of mucking about in practice to get
it to work.  I would not make another Moxon unless I'm exactly
duplicating something else (right down to the wire) - otherwise
both elements need trimming & WA1X's approach (I think it was)
is probably the best way to go about it.

Enjoy!

73, VR2BrettGraham

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[Charles Greene-2]

Brett,

Tnx for the comments.  Tried the antenna today and successfully
operated simultaneously with both transceivers on the phone
bands.  There was some second harmonic noise of the 40 meter
transmitter on 20 when an ICOM 746 Pro was used at 100 watts; none
when a K2 at 10 watts was used.  The noise was about S5 and could be
easily tuned out as it It was on certain rather narrow
frequencies.   Voltage on 20 meters coming through the filter was 55
uv, 0 to peak, measured with a scope when the ICOM was
transmitting.  No noise at all on 40 meters when the 20 meter
transmitter was transmitting.  Voltage on the line after the 40 meter
filter was 7 uv, 0 to peak.  The antenna seems to have good
gain.  Worked a bunch of 6's in the CA QSO contest as well as some
stations in IO and MO on 20.  On 40, contacts ranged from E. PA to
Pittsburgh and other states, VA to Ont. with similar distances from
RI.  Signal reports were good.  Antenna is pointed West.  Terrain
flat, farmland, about 50 feet ASL.

See below for other comments.

Chas, W1CG

At 08:07 PM 9/30/2005, VR2BrettGraham wrote:

>W1CG continued:
>
>>To answer your question, I am using stranded, silver plated, teflon
>>insulated #16 wire.  It is plenty strong.  I have a 3/16" Dacron line
>>between the two poles to take the strain off the wires.  This also
>>decreases the vertical bend and completely eliminates the horizontal
>>bend of the two poles.
>
>Presumably you know the dielectric constant of that insulation,
>verified that the wire you have is in the same neighborhood &
>done all your modelling based on that figure?

I have previously assumed that any wire insulated or not, in space,
has the same velocity factor as bare wire.  Why wouldn't it?  I can
see that a twisted pair, or feed line would be affected by velocity factor.


>If so, then you can see how ground dominates & if not, then
>between both ground & insulation your elements are nowhere
>near where you think they are.

I don't understand what you mean.

>>(To review, the antenna is a 40 meter Moxon wire beam with a 2
>>element 20 wire meter beam inside.  There are two supports, 22' long
>>fiberglass poles at each end, spaced 45 '.  There are two feed lines.)
>>
>>We put the antenna up today for our annual special event at for the
>>Harvest Faire at the Norman Bird Sanctuary in Middletown, RI for this
>>weekend.  Listen for us on 20 and 40.  Call is W1SYE, Newport County
>>Radio Club.  (See Sept QST, special events).
>>
>>The antenna is about 30' high on one end and about 25' on the other,
>>from a portable mast to a tree.  The Fo and Zo is not much different
>>from what it was at 21'.  Fo is about 14.00/7.00  MHZ .  SWR is 1:1,
>>50 ohms on both bands per MFJ 159B.  2:1 band width is (top
>>frequency) 14.4 MHz and 7.25 MHz resp.  I still want to move it up to
>>14.2 and  7.25 MHz.  It's a very nice beam; doesn't sag much and it
>>is easy to erect.  The weight is about 18# which includes
>>everything supported.
>
>Not many 2-element 40m beams that can be robust & only weigh
>that much - not to mention less wingspan & far better F/R than a
>yagi.
>
>>The feed lines are two lengths of double shielded RG-58 (TRF-58).  I
>>am going to try simultaneous operation on 40 and 20 using 20 and 40
>>meter bandpass filters by Array Solutions.  The 40M filter has an
>>insertion loss of 70 dB on 14 MHz and the 20M filter has an insertion
>>loss of 35 dB on 7 MHz.  I will use my K2/100 with a LDG Z-11 tuner
>>and the club's  Ten Tec Jupiter with its LDG tuner.   I will try my
>>other K2 with KAT2 in case the Jupiter overloads on receive.  I don't
>>know how this will work out.  Calculations say it won't work at 100
>>watts as there is not enough attenuation, but I will try it and
>>report results.  There must be some power level of the transmitters
>>that will work.  It would be handy for field day, but if it doesn't
>>work we will just have to put the second transceiver on 80 meters
>>using another antenna.  Or else use separate receiving antennas.  The
>>K2 with the KAT2 can do this;  I don't know about a K2/100 with a
>>KAT100.  Maybe someone can enlighten me.
>
>With two 400 watt rigs into two bands of a tribander simultaneously,
>those filters will work - though without stubs the 2nd harmonic of
>the 40m station will render some number of dozens of kilocycles on
>the higher band useless.

I want to add a stub or stubs.  I am thinking of a 1/4 wave 40 meter
shorted stub, on the 40 meter feed line.  Where is the best place to
put it?  (at transmitter before filter, after filter, or at
antenna).  I will try it tomorrow and can easily try it at all three
locations.  How about stubs on the 20 meter feed line?

>Be sure to decouple the feeders at
>the feedpoints, too.
>
>Look at how each driver looks as you connect, disconnect or short
>the far end of the feeder to the other driver.

I did that and there is no change from open to 50 ohms to shorted.

>I would imagine that your
>antenna probably has the two bands' drivers electrically closer &
>therefore you will have far greater interaction between the two bands
>than on my tribander.  Hairpins seem to work pretty good on that,
>but that means more trimming.
>
>Anyway, I think the key point is the wire & like I said about my
>bare wire Moxon, there's a bit of mucking about in practice to get
>it to work.  I would not make another Moxon unless I'm exactly
>duplicating something else (right down to the wire) - otherwise
>both elements need trimming & WA1X's approach (I think it was)
>is probably the best way to go about it.

Remind me what WA1X's approach is again.


>Enjoy!
>
>73, VR2BrettGraham

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[VR2BrettGraham]

W1CG replied:

<one big snip>

>>Presumably you know the dielectric constant of that insulation,
>>verified that the wire you have is in the same neighborhood &
>>done all your modelling based on that figure?
>
>I have previously assumed that any wire insulated or not, in space, has
>the same velocity factor as bare wire.  Why wouldn't it?  I can see that a
>twisted pair, or feed line would be affected by velocity factor.

Because, quite simply, it does.  You are not above the laws of
RF black magic - never were & never will be, full stop.

Shorten things by 2-3% - perhaps more - in your model & see
what happens.

That is what happens when you use insulated wire without
taking into consideration the effect of the insulation.

On 40m & somewhere around about a quarter-wave above
ground - without any consideration for the insulation - IMHO
nothing will be where you expect it to be.  It never is for me.

<snip again>

>Remind me what WA1X's approach is again.

Tune elements such that they are resonant reasonably close
to where they need to be - both driver & reflector.

In a nutshell, not really possible to make a Moxon without a
bit of tweaking.

Mine - made of wire that has very little dielectric in contact
with it (just the end insulators) - required quite a bit of trimming
before it showed reasonable match _and_ performance based
on pattern.  Remember, this was a 10m Moxon at a height of
wavelengths greater than yours above "ground".

Get higher up & things should change, but I really believe you
are taking a hit from these two very significant factors (with
ground _so_ close that it might be greater than the insulation).

Compare against another antenna & I suspect you will see - as
I did.

As for simultaneous operation, other than harmonics & spurs,
the other concern is phase noise & K2 is quite good in
that department.  Harmonics usually are more of a problem on
CW due to relationship of bands (less so in ITU R2, where
2 x 40m SSB band is mostly above 14.35 Mc).

But as this all has to do with evil competitive operation &
judging from lack of interest from the list, best to terminate
this discussion.

GL.

73, VR2BrettGraham

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[Charles Greene-2]

Gil,

It performed well during our special event this weekend.  We had it
up at an average height of 25'.  We used it on both 20 and 40 meters
simultaneously using Array Solutions RF filters with a little 2nd
harmonics or phase noise on 20 from the 40 meter transmitter.  We
were able to reduce this interference about 18 dB using a shorted
coax stub on the 40 meter feed line.  The resonant frequency is 3 to
5% low from the design value, which turn out to be caused by my not
taking into account the velocity factor of the insulated wire I used
for elements.  Hopefully, we will get everything corrected for field day.

Chas, W1CG

At 09:38 AM 10/3/2005, Gil Stacy wrote:

>Hi Charles,
>
>The trimming technique of W1AX looks like a well-thought out
>approach to solving the idiosyncracies of location diffferences in
>erecting the antenna.  I've always been impressed by the Moxon
>technology in using wire to erect a simple gain antenna.  I emailed
>W1ZY about his switchable 40 meter Moxon and never heard back.  The
>sound file of his front and back switching is very impressive.  I
>suppose he had a lot of "cutting and trying" to perfect it as well
>as more relays than one can imagine.  Let us all know how your
>antenna performs.
>
>73, Gil NN4CW
>

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[VR2BrettGraham]

Okay, found it - WA1X's technique for tuning a Moxon rectangle:

http://lists.contesting.com/archives//html/Towertalk/2005-03/msg00852.html

My apologies for not finding it sooner.

73, VR2BrettGraham

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[NR5A]

I guess I don't understand at all how to use the spot feature. For all I
know my K2 may not even have it. I just listened to N0SS 2 different wav
files and still can't figure out what I'm doing.  When I hit the Spot
button, same as Rit only held longer I get SE L  143. The number changes as
I turn the main tuning dial but the tone completly wipes out the signal I'm
listening to, no matter how loud it is. Maybe I need one of those LED Tuners
I've been reading about. What am I doing wrong??

Jerry - NR5A - South Dakota


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[Brian Mury-3]

On Tue, 2005-10-04 at 20:40 -0600, NR5A wrote:
> When I hit the Spot button, same as Rit only held longer I get SE L  143.

You are using the wrong button. You activate the spot feature by holding
down the PRE/ATT button, not the RIT button.

Note that the yellow labels indicating the buttons secondary functions
are below the buttons, while the white labels indicating the primary
functions are above the buttons.

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[Tom Hammond-3]

Hi Jerry:

>I guess I don't understand at all how to use the spot feature. For all I
>know my K2 may not even have it. I just listened to N0SS 2 different wav
>files and still can't figure out what I'm doing.  When I hit the Spot
>button, same as Rit only held longer I get SE L  143. The number changes as
>I turn the main tuning dial but the tone completly wipes out the signal I'm
>listening to, no matter how loud it is. Maybe I need one of those LED Tuners
>I've been reading about. What am I doing wrong??

Invoking SPOT is NOT by pressing-holding RIT, but by pressing-holding the
PRE-ATT button!

If you press-hold RIT, you're invoking the PF1 user-programmable function,
which happens to default to the MENU | ST L (sidetone level) setting.

If your ST L value is currently set to 143, it's probably MUCH too loud for
90% of the spotting uses you'll use it for.

Try this...

1. Press-hold PF1 (RIT) to go to the ST L menu and then crank the VFO
    knob DOWN to set ST L to a level of between 25 and 40. This should
    give you a CW sidetone level which you can still hear adequately
    while sending, but one which won't 'swamp' received signals when
    you attempt to use it for zero beating.

    Exit ST L by pressing MENU briefly.

2) Be sure you have your tuning RATE set to show the last two decimal
    places in the frequency display.

3) Find a signal on the band... doesn't have to be a blindingly strong
    signal but let's not start with a water-weak signal either. Maybe
    find someone who is 569 to 589.

4) Press-hold SPOT (PRE-ATT) to turn on the SPOT tone.

    This should allow you to hear both the SPOT sidetone AND the signal
    from the other station.

5) Now, slowly crank the VFO knob until the tone of the received station
    matches that of the SPOT tone.

    As the two tones come closer together (esp. when within 30-40 Hz),
    you will start to hear a secondary beat note between them (this is
    the difference tone between the two higher-pitched tones). As you
    continue to tune the VFO, this beat note should get slower and
    slower until you can easily hear individual beats. At this same time,
    the tone of the received station should 'disappear' behind the SPOT
    tone (that's what I was trying to demonstrate in the WAV file you
    played).

    Once you have matched the two tones, such that the received signal
    disappears behind (and within) the SPOT tone, you're zero beat with
    the received signal.

One VERY IMPORTANT point of using the SPOT tone for zeroing in on a
received signal is to not have the SPOT tone so darn strong that it
completely swamps out the received signal. What you should try to do is to
find a SPOT tone level which more or less equals the volume of the tone
from the received signal. The closer the two tones are in level, the more
easily you can zero beat them and the more easily you should be able to
hear the beat note between the two signals.

Learning to properly zero beat a signal is not necessarily an instantaneous
success. It might take a bit of time to master it, but it is NOT difficult,
and once you 'get' it (the technique), you will never lost it again.

If I can help in any way, please drop me a note.  Maybe I'll try to make a
better WAV file example of how to zero beat.

73,

Tom Hammond    N0SS

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[JEAN-FRANCOIS MENARD-3]

 You can also use the SPOT button with the RIT feature to ZERO BEAT de station...

Select a CW station.... activate de SPOT feature... activate the RIT feature... decrease the RIT by 700 Hz... and finish to ZERO BEAT the station now with the main VFO knob... once ZERO BEAT... un-select the RIT... a 700 Hz will be added because you release the RIT.. and you will be, at least very near, the same frequency of the CW station.

This trick works with all radio that have a SPOT and RIT feature... very common on most recent rig.

73

On Wednesday, October 05, 2005, at 06:19AM, Tom Hammond <[hidden email]> wrote:

>Hi Jerry:
>
>>I guess I don't understand at all how to use the spot feature. For all I
>>know my K2 may not even have it. I just listened to N0SS 2 different wav
>>files and still can't figure out what I'm doing.  When I hit the Spot
>>button, same as Rit only held longer I get SE L  143. The number changes as
>>I turn the main tuning dial but the tone completly wipes out the signal I'm
>>listening to, no matter how loud it is. Maybe I need one of those LED Tuners
>>I've been reading about. What am I doing wrong??
>
>Invoking SPOT is NOT by pressing-holding RIT, but by pressing-holding the
>PRE-ATT button!
>
>If you press-hold RIT, you're invoking the PF1 user-programmable function,
>which happens to default to the MENU | ST L (sidetone level) setting.
>
>If your ST L value is currently set to 143, it's probably MUCH too loud for
>90% of the spotting uses you'll use it for.
>
>Try this...
>
>1. Press-hold PF1 (RIT) to go to the ST L menu and then crank the VFO
>    knob DOWN to set ST L to a level of between 25 and 40. This should
>    give you a CW sidetone level which you can still hear adequately
>    while sending, but one which won't 'swamp' received signals when
>    you attempt to use it for zero beating.
>
>    Exit ST L by pressing MENU briefly.
>
>2) Be sure you have your tuning RATE set to show the last two decimal
>    places in the frequency display.
>
>3) Find a signal on the band... doesn't have to be a blindingly strong
>    signal but let's not start with a water-weak signal either. Maybe
>    find someone who is 569 to 589.
>
>4) Press-hold SPOT (PRE-ATT) to turn on the SPOT tone.
>
>    This should allow you to hear both the SPOT sidetone AND the signal
>    from the other station.
>
>5) Now, slowly crank the VFO knob until the tone of the received station
>    matches that of the SPOT tone.
>
>    As the two tones come closer together (esp. when within 30-40 Hz),
>    you will start to hear a secondary beat note between them (this is
>    the difference tone between the two higher-pitched tones). As you
>    continue to tune the VFO, this beat note should get slower and
>    slower until you can easily hear individual beats. At this same time,
>    the tone of the received station should 'disappear' behind the SPOT
>    tone (that's what I was trying to demonstrate in the WAV file you
>    played).
>
>    Once you have matched the two tones, such that the received signal
>    disappears behind (and within) the SPOT tone, you're zero beat with
>    the received signal.
>
>One VERY IMPORTANT point of using the SPOT tone for zeroing in on a
>received signal is to not have the SPOT tone so darn strong that it
>completely swamps out the received signal. What you should try to do is to
>find a SPOT tone level which more or less equals the volume of the tone
>from the received signal. The closer the two tones are in level, the more
>easily you can zero beat them and the more easily you should be able to
>hear the beat note between the two signals.
>
>Learning to properly zero beat a signal is not necessarily an instantaneous
>success. It might take a bit of time to master it, but it is NOT difficult,
>and once you 'get' it (the technique), you will never lost it again.
>
>If I can help in any way, please drop me a note.  Maybe I'll try to make a
>better WAV file example of how to zero beat.
>
>73,
>
>Tom Hammond    N0SS
>
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>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
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>
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>Elecraft web page: http://www.elecraft.com
>
>

==========================================
/¯\/¯\/¯\/¯\/¯\/¯\   JEAN-FRANCOIS MENARD
 V  A  2  V  Y  Z    [hidden email]
\_/\_/\_/\_/\_/\_/

Elecraft K2 #4130
Elecraft KX1 #999

http://homepage.mac.com/jfmenard
==========================================

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[Fraser Robertson]

I saw this mentioned on here a few days ago but I missed the original
announcement, and can't see anything about it on the Elecraft site.

Can anyone enlighten me please?

Thanks, Fraser G4BJM

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[Ron D'Eau Claire-2]

Fraser, G4BJM wrote:

I saw this mentioned on here a few days ago but I missed the original
announcement, and can't see anything about it on the Elecraft site.

Can anyone enlighten me please?

---------------------------------------------------
Below is the original announcement from Wayne.

Ron AC7AC

-----------------------

The K2's VCO (voltage-controlled oscillator) may be susceptible to
low-frequency modulation by very large power transformers, such as
those in linear amp power supplies and antenna rotator controllers.
Such modulation can usually be eliminated by simply moving the
equipment away from the transceiver. In difficult cases, magnetic
shielding can be used, and we've created a modification kit for this
purpose (Order #K2VCOSHLDKT).

The mod kit provides a smaller replacement core for transformer T5, a
high-permeability ferrite sleeve, and associated hardware. The ferrite
sleeve is installed over T5, greatly reducing the effect of nearby
strong magnetic fields. In addition, slug-tuned inductor L30 must be
electrically disabled since it, too, is affected by magnetic fields.
With L30 out of the circuit, the VCO inductance can still be adjusted,
if necessary, by slightly squeezing or spreading the turns of T5.

The kit is priced at $10. For more information, see our parts order
page:

    http://www.elecraft.com/order_form_parts.htm#K2%20Parts

73,
Wayne, N6KR

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