It is also my experience that stations in China and Southeast Asia in general
do not hear well at all on the low bands. One exception is BG2AUE. I have
worked him multiple times on 80m CW from my QTH in the Boston area. He hears
extremely well on 80. Every single time I've worked him there,
Congratulations Steve for this epic contact! As already pointed out, much of
the difficulty is the very high level of QRN on Ross's end. He gets almost
daily thunderstorms. My experience coincides with what Dave, W0FLS, said. The
most favorable conditions to work 9M2AX are around the
If you are going to use the NCC-2 to null a nearby in-band transmitter, I think
it's very likely that the NCC-2 will get overloaded by the extremely strong RF
and not be usable. I've tried this before and found that to be the case. In
fact, I designed my own totally passive nuller to get
I heard them a couple nights ago on 160 CW, around 2330Z, roughly an hour
after local sunset in W1. They were actually quite strong on peaks but
there was deep QSB that took them down to almost nothing. They seemed to be
having trouble hearing. I heard them come back to N1DG but all the other
Another tool I've found indispensable for setting up and troubleshooting phased
vertical RX arrays is a two-port VNA. I use an Array Solutions VNA-2180 (now
discontinued) for critical measurements. I also have a NanoVNA H4
(https://nanovna.com/) which is a very "affordable" VNA that can be
Here in the Greater Boston area, the signal peaks from the southwest on my
8-circle array. It's not real strong, varying between S4 and S6. I can tell
there is some audio in there but it's not strong enough to identify.
73, John W1FV
-Original Message-
From: Topband
The WD8DSB mini-flag truly is a fantastic RFI-hunting tool. When I saw the
original article in QST, I recognized immediately that this was a great
"invention" by WD8DSB. Like many of you, I deal with quite a bit of man-made
RFI on 160m, so I bought one of the very first ones sold by DX
Here is additional information on the 9-circle low-band receiving array. It
was originally designed for operation on both 160 and 80 meters.
It was based on a couple articles I wrote for NCJ in the September/October
and November/December issues in 2011. The design was turned into a set of
> So how is the QRN doing over there now? Any likelihood of 160m activity
from
> the USA soon?
>
> Roger G3YRO
The QRN on the East Coast is still fairly high most evenings, but there is
propagation to Europe. OK1CF is on regularly and is usually Q5. Also a few
G's have been heard recently with
Some evenings I hear noise-like transmissions, approximately 3 kHz wide,
around 1860 and 1900 kHz that appear to be originating in Europe. I presume
they are not amateur signals. On European SDR's they are quite loud and
operating continuously every day. I find they are actually useful as
Even in a quiet rural location, the limiting noise on 160 will be external
atmospheric noise. Improving RDF will generally improve your signal/noise
ratio against the atmospheric noise. There are exceptions when there is a
source of high noise, like thunderstorms, in the same direction as the
I have a low dipole, about 10 feet high, that I use as an alternate receiving
antenna on 160. My main receiving antenna is an 8-circle array of short
verticals. The vertical array is almost always much better for DX, but once in
a while the low dipole is better, sometimes dramatically so.
EZNEC is correct. Adding more radials, even long ones, in a specific
direction won't preferentially favor the direction in which the radials are
added. It will help raise the overall efficiency of the antenna to a
degree, depending on how many radials are already in place, but any
improvement
.
This is best done on the feedlines themselves, installing feedline chokes a few
feet away from the combiner.
73, John W1FV
From: Dennis W0JX [mailto:w...@yahoo.com]
Sent: Tuesday, November 30, 2021 12:48 PM
To: topband@contesting.com; John Kaufmann
Subject: Feedline Choke Placement in RX
You can make a feedline choke with snap-on ferrites as follows: wind 4
turns of the feedline through 5 snap-on cores of Fair-Rite part #0431176451.
The core has an inner diameter of about 3/4 inch and 4 turns of RG-6 is the
limit of what will fit in the core. However, using 5 cores will provide
On 160 and 80, I have an 8-circle vertical receiving array. On very long
paths, it is not uncommon to see skewing. The most common example is the
path to JA, where the direct path heading should be about 330 degrees from
my QTH in New England. However, for the last couple winter seasons, when
I have the DX Engineering preamp that I use with the DX Engineering portable
flag and can confirm the 4.5 dB noise figure. Using the methods I described
here in an earlier post, I measured the noise figure as between 4 to 5 dB.
Also I measured the gain (S21) from 0.1 to 30 MHz with my VNA-2180.
ebruary 25, 2021 10:39 PM
To: topband@contesting.com
Subject: Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)
On 2/25/2021 5:16 PM, John Kaufmann via Topband wrote:
> The P3 averages power, not amplitude, so using longer averaging times just
> smooths the display and doesn't reduce rando
, 2021 8:03 PM
To: topband@contesting.com
Subject: Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)
On 2/25/2021 2:29 PM, John Kaufmann via Topband wrote:
> The P3 noise measurement bandwidth was about 100 Hz in my measurements.
I hope that everyone realizes that setting a high va
The P3 noise measurement bandwidth was about 100 Hz in my measurements.
Quoting from the P3 user's manual, "the effective bandwidth of the P3 is
generally one display pixel, which is approximately span / 450. I used a span
of 50 kHz, so it comes out to 111 Hz. Because the relationship is
we probably should move this discussion
over to the RFI Reflector or e-mail me direct.
73,
Don (wd8sb)
On Tue, Feb 23, 2021 at 1:26 PM John Kaufmann via Topband
wrote:
Some of you may have seen the article by WD8DSB in the latest issue of QST.
I believe WD8DSB is on this reflector
As a follow-up to my original post, here are a few additional comments.
Don, you mention that you designed the mini-flag for a deep null off the
back at low elevation angles, which is entirely understandable. As I said
in my earlier post, the null is very pronounced in the AM BCB on local
Some of you may have seen the article by WD8DSB in the latest issue of QST.
I believe WD8DSB is on this reflector. His article describes a mini-flag
antenna that can be used for direction-finding. The neat thing about this
antenna, besides its compact size, is that it is unidirectional and is
This antenna was clearly working well at UA2FW in the recent CQ 160 contest.
When I listened on the band, UA2FW was, by far, the strongest signal coming
out of Europe in mediocre conditions. Normally northern Europe, including
UA2, is at a disadvantage in terms of propagation to the US. Also,
Hi Charlie,
What you see in your TDR sweep of the RG6 is absolutely normal. I've seen
exactly the same thing. The rise in apparent impedance with distance is caused
by the loss in the cable. If you had a lower loss cable, the TDR trace would
be flatter. As long as you don't seen any
We got a piece of the action, too, in New England. I worked JH1HDT, HL5IVL,
and VK6LW just before my SR. HL5IVL peaked up to 579 right at SR. We only get
propagation to HL very infrequently here in W1. JA7BXS was in there but he
first fired up on the disturbance on 1825 and was being
I have two receiving antennas on 160: an 8-circle vertical array and a low
dipole up 10 feet. I have been noticing that in the first part of the
evening, the dipole often hears Europe as well as, or nearly as well as, the
8-circle. This appears to indicate that the signals are arriving at
Here in the Boston area it was peaking from the SW on my 8 circle array.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com]
On Behalf Of w...@w5zn.org
Sent: Friday, December 11, 2020 7:24 AM
To: David Raymond
Cc:
I have the RPA-1, the predecessor to the RPA-2. It's an outstanding preamp
with a low noise figure and very high dynamic range. I'm sure it would make a
fine BOG preamp.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com]
I use the VE7CC node for spots. You can filter out FT8 spots on VE7CC via the
'set/noft8' command.
73, John W1FV
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
For signals that arrive from directions that are in between the main lobe
headings of a 4-square, you will lose up to a few dB of S/N compared to having
8 directions. Whether that matters to you is purely a personal performance vs.
complexity/cost decision. If 90% of what you work is covered
Inverted vee dipoles do produce some vertically polarized radiation off the
ends. However, that vertical component has maximum gain at zenith, i.e.
straight overhead. It does not contribute to any significant low-angle
radiation. You can see this by doing an antenna model.
73, John W1FV
Steve,
An alternative is to do the cancellation with all passive circuitry. You
can find some designs on the Web but you'll have to build them yourself. An
example (one that I built) is this one from WA1ION:
https://www.pa4tim.nl/wp-content/uploads/2011/02/passive_bb_phasing.pdf.
The drawback to
tmospheric noise
have to go up by at least 3dB.
I think I have this right, John, but feel free to shoot holes in it if I
don't. I know thinking about it made my head hurt.
73, Mike W4EF
On 3/12/2020 4:37 PM, John Kaufmann via Topband wrote:
> To assess the impact of amplifier circuit noi
To assess the impact of amplifier circuit noise in "active" receive arrays,
we only need to be concerned with the contribution of amplifier circuit
noise relative to atmospheric noise. The details of how signals are phased
in any particular array do not matter. The objective is to keep the
Lee,
I think you are confusing voltage and power. For incoherent sources like
amplifier noise, the voltages of multiple incoherent sources add in a
root-sum-squared (RSS) fashion. The voltage of the sum of eight incoherent
sources is square root of eight times a single noise source, assuming
As the designer of the YCCC high impedance feedpoint amplifier, let me
address some issues related to the design of the YCCC amplifier as well as
feedpoint amplifiers in general. If you don't want to read a lot of
technical gobbledygook, please disregard this message.
The YCCC uses an AD8055 RF
It's also very strong in the greater Boston area. The signal is very steady
with only a few dB of very slow fading. I get a heading of roughly SE,
which would put it towards Cape Cod or Rhode Island, but it could be
anywhere between E and S. It doesn't exhibit strong directivity on my
8-circle
Greetings Topbanders,
Matt, KC1XX, is spending the winter in HI3 and asked me to relay this
message to all of you. He is on the air as HI3/KC1XX but is experiencing
terrible line noise at his present location. He hears lots of stations
calling him on the low bands but he is having great
I'm looking for a source for durable ladder line for making two-wire
reversible Beverages for use at the KC1XX contest station. In the past
we've used the line sold by DX Engineering but over the years we've found
that the plastic spacers between the wires become brittle and break off. It
may be
I have an 8-circle array in the woods. The tallest trees in my area are about
60-70 feet, so your trees might be larger and denser than mine. However, my
system works very well, judging by the fact that its pattern seems to match
very closely the theoretical pattern for this array. In other
. That will work.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John
Kaufmann
Sent: Saturday, February 2, 2019 11:56 AM
To: topband@contesting.com
Subject: Re: Topband: Rx splinter
The BCC splitter design suggested by PC2A is based on the "
The BCC splitter design suggested by PC2A is based on the "magic tee" splitter.
An excellent tutorial on magic tee splitters can be found on W8JI's Web site:
https://www.w8ji.com/combiner_and_splitters.htm. These splitters are very
easy and inexpensive to build.
A 1:2 splitter design
On 160 I've used a vertical wire of 20 feet with a 1000 pF variable
capacitor to detune a tower at its base. You can scale that to 80.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of terry
burge
Sent: Friday, December 21, 2018 9:22 PM
From: Richard (Rick) Karlquist
Sent: Wednesday, November 28, 2018 7:02 AM
To: jkaufm...@alum.mit.edu ; 'Jim Thomson' ; 'TopBand List'
Subject: Re: Topband: Detuning TX ant + QSK
On 11/28/2018 5:18 AM, John Kaufmann wrote:
> Jim,
>
> I use Gigavac GH-1 vacuum relays for detuning
Jim,
I use Gigavac GH-1 vacuum relays for detuning my TX antennas when receiving.
The contact closure/release time is 6 msec. You have to dial in enough QSK
delay in your radio so that you don't hot-switch the relays.
73, John W1FV
-Original Message-
From: Topband
s
JC
N4IS
From: John Kaufmann
Sent: Tuesday, November 27, 2018 8:16 AM
To: n...@n4is.com; topband@contesting.com
Subject: RE: Topband: Vertical antennas aren't always best for DX
In considering the *total power* radiated by any antenna, you need to look
at the 3-dimensional antenna pattern,
, you can check by yourself using EZENEC if you don't know how to
calculate the fields.
There is no misleading here.
73
JC
N4IS
-Original Message-
From: Topband On Behalf Of John Kaufmann
Sent: Monday, November 26, 2018 8:53 PM
To: topband@contesting.com
Subject: Re: Topband: Vertical
The statement that the half of a horizontal dipole's radiation is vertically
polarized is misleading and needs qualification. There is a vertically
polarized component off the ends of the dipole but it is only of consequence
at takeoff angles approaching 90 degrees, in other words straight
I would like to add some additional observations to the ongoing discussion
about horizontal vs. vertical antennas on 160. At the KC1XX contest station
where I operate the low bands (160 and 80), we just installed two new
horizontal dipoles for 160. For years, KC1XX has used a 3 element inline
You can find a schematic on p.54 of the user's manual which can be download
from the DXE Web site:
https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.
pdf.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Peter
I designed the YCCC preamp so I can answer the question about the AD8055 op
amp.
As used in the YCCC preamp, the linearity is actually very good. We use a
YCCC receiving array at KC1XX in a multi-operator, multi-transmitter
environment with 20 foot receive verticals. That's a pretty severe RFI
I was one of the lucky ones to work VK6VZ on LP last November 7. I got him at
2128Z with signals peaking from the east. It was exactly at my sunset. I was
followed by two other W1 stations before the opening ran out. Good luck to all
on this one!
73, John W1FV
-Original
or 3 of db "out of round".Some other
modeling I did showed small pattern skew even with 3 or 4 radials removed.
So what am I missing?
Grant KZ1W
On 10/21/2018 15:22 PM, John Kaufmann wrote:
> We just went through the exercise of tuning up the elevated radials on the
&
We just went through the exercise of tuning up the elevated radials on the
KC1XX 160m vertical array in advance of the upcoming CQWW DX Contests.
The first thing is to make each of the radials look as electrically
identical as possible. We assume the length of the vertical element is
fixed and
Here's another method that's based on the engineering textbook transmission
line equation and use of an impedance analyzer to make an impedance
measurement.
You can look up the transmission line equation on Wikipedia:
https://en.wikipedia.org/wiki/Transmission_line. Scroll down the page to
the
I have also observed enhanced, and sometimes extraordinary, propagation at the
onset of disturbed conditions. A recent notable example was the LP QSO with
VK6VZ that I reported last month:
http://lists.contesting.com/pipermail/topband/2017-November/052869.html. At
the time of the QSO, the K
It was certainly a great opening between VK6 and my QTH (at W1FV). As Steve
indicated, we had been trying to make a LP QSO for a number of years. In
the past I had heard him a few times but it was marginal and we were never
able to connect for a two-way. This time it was easy.
Steve's e-mail
Another sign of things looking up on Topband: I worked VK6VZ on long path
at 2128Z today, right at my sunset. Steve peaked 569 from the ENE and he
also worked at least a couple other W1's. I also had partial copy on VK6LW
CQing around the same time but Kevin was right at the noise and not quite
I use the "Key Out" line of my K3S to drive the base of a homebrew
transistor switch that, in turn, drives a relay coil at the base of my
antenna. There is an isolation diode between the K3S keying line and the
switching transistor because I also use the same keying line to switch my
AL-1200 QSK
What Frank says (below) is 100% correct. There is simply no substitute for
time in the chair. I never use any propagation prediction methods. I know
from more than three decades of lowband DXing and contesting experience when
the openings are most likely to occur but I can't predict them in
In principle, any *odd* multiple of 4.118 MHz (the frequency where the cable
is 1/4 wavelengths long) will work when the far end of the cable is
open-circuited. If you short-circuit the far end of the cable, then look
for X=0 at *even* multiples of 4.118 MHz.
73, John W1FV
-Original
(Note: disregard my earlier incomplete post)
Carl K9LA: " But in my opinion (and in the opinion of others) the deep and
long solar minimum between Cycles 23 and 24 (2006-2010) didn't live up to
this axiom compared to the not-so-deep and not-so-long solar minimum between
Cycles 22 and 23
> As for low band propagation being better at solar min, I grew up believing
in this axiom. But in my opinion (and in the opinion of others) the deep and
long solar minimum between Cycles 23 and 24 (2006-2010) didn't live up to
this axiom compared to the not-so-deep and not-so-long solar minimum
I have been observing an intruder whose behavior is unlike anything I have
seen before. It consists of a comb spectrum of CW tones in the 160m band.
They pulse on and off at a regular interval. There is never any form of
identification transmitted by it.
Thanks to my Elecraft P3 panadapter,
I also use a vertical phased array with 1/8-wave spacing on 80m. I did this
because of limited space. Like PE5T describes in his post below, I used the
method in ON4UN's book and originally described in a series of articles by K2BT
in Ham Radio magazine (no longer in publication) in the
I was lucky enough to visit W1BB in person back in the early 1970's. I got
to see his home station and the famous water tower station. As I recall the
two stations were a bit further apart than walking distance, unless you
didn't mind walking a lot. We drove there from his home.
I'm almost
I received a number of replies on the subject of the mystery CW/QRSS signal
that I've been hearing every day on 1814.0 kHz. It's strong at my QTH just
west of Boston. Most people don't hear it and some do hear something but I
don't think it's what I am hearing.
Here is some additional info.
Based on the RDF metric, which is a very useful way of comparing antennas,
the differences between the "best" arrays is not that great--maybe 1 to 2
dB. I have used Beverages and a number of different receiving arrays, and
found that in practice it is very hard to discern 1 dB RDF differences
For weeks I have been hearing a fairly strong persistent signal on 1814.0
kHz. It is either a continuous carrier or a series of slow CW dashes. The
signals I hear periodically from buoy beacons come and go. This one is
persistent. I hear it only in darkness and not in daylight, so I presume
A relatively new source of RF noise is solar panel installations. These are
becoming more widespread and I'm now hearing multiple reports of solar panel
noise from other hams in my area. The culprit seems to be the power
inverters that use high speed switching circuits and radiate through the
> A reversible array is far and away the best way to convince yourself
> that you have a working receive antenna system. If you reverse it and
> nothing ever changes, well, you're listening to some other antenna!
> Some (e.g. YCCC array) are supposed to be far more sensitive to near-field
>
In general, any metal in the near field of the array will have an effect on
pattern. This includes radials under the array. It's hard to predict what
the results will be in a particular situation, but it can be modeled in
EZNEC or other modeling programs. I've done this in the past and the
In my earlier post, I neglected to mention the NCJ article was published in
2011.
73, John W1FV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John
Kaufmann
Sent: Monday, December 07, 2015 8:34 PM
To: 'Glenn Biggerstaff'; topband@contesting.com
Cc
Hello TopBanders,
I am the author of the original NCJ article, published in September/October
and November/December issues, which is the basis for the YCCC/DX Engineering
RX array. I also collaborated extensively with DXE to develop the kits that
are now available exclusively through DXE. I
I just wanted to add another data point to this subject. I have heard LP
JA's on 160 on several occasions from my location in FN42 (eastern MA),
anywhere from 2120Z to 2200Z in December and January, going back to 1994 or
thereabouts. I was never able to work any because they were working Europe
W1BB's water tower shack was in a little hut at the base of the tower. I
visited Stew back in the 1970's and got a tour of that QTH. As I recall,
the shack also served as a civil defense facility, which is the connection
that allowed Stew to operate from there. I remember Stew telling me that
W8JI: The last good DXCC's were when we had a mileage limit. Even then,
someone could use a second site. It was actually common to use second
sites. W1BU did it from a swamp, even W1BB had two stations.
Just for the record, it is true that W1BB had two stations, but they were in
the same town
-Original Message-
From: JC [mailto:n...@comcast.net]
Sent: Friday, December 19, 2014 5:15 PM
To: 'John Kaufmann'; 'Top Band Contesting'
Subject: RE: Topband: Non-resonant receive antennas
Hi John
What is the orientation of you low dipole? I assume similar to XZ0A it is
broadside N-S. In 2010
A few years ago, I put up a low, non-resonant dipole, about 150 feet long
and 10 feet high for use as an auxiliary receiving antenna on 160. My main
receiving antenna was and still is an array of short verticals. What I
found at my W1 location after I installed the dipole is similar to what N5IA
: Wednesday, December 17, 2014 3:19 PM
To: Lee K7TJR; 'Terry Posey'; 'John Kaufmann'; topband@contesting.com
Subject: Re: Topband: 8 circle: DXE vs Hi-Z
All this discussion about RDF overlooks the issue of polarization. If you
make an array of verticals with a certain RDF (assuming noise comes from all
A few comments based on my own experience with various receiving arrays:
Circle diameter of the Hi-Z array:
A circle diameter of 200 feet is specified for the Hi-Z 8-circle array on
160m. In fact, I have found that there is nothing magic about 200 feet.
It happens to be a good compromise
It is still coming in after my SR (1200Z) but dropping in strength. Given
the hour, it is definitely not coming from EU. The origins are in NA.
73, John W1FV
_
Topband Reflector Archives - http://www.contesting.com/_topband
Stay tuned, and any additional reports are welcome...I think we have
narrowed it down to something in the Maine/New Brunswick.Nova Scotia areas.
73,
Doug K1DG
I would also put Newfoundland in the region of interest. From my location
in the greater Boston area, the direction of arrival is
I'm not hearing it either at 0054Z. This transmitter appears to go on and
off, so we can't deduce much unless we know it's on.
Joe (VO1NA), do you have a directional RX antenna? If so, your readings
could really help narrow down the location.
73, John W1FV
-Original Message-
From:
Same estimated heading (~75 deg) from the Boston area and same as last
night. The relatively big signal strength suggests something in NA rather
than EU. But that would place it almost out a sea from here, or possibly
very southern VE1 or FP8. Is there anyone from that area that can give a
It peaks at a heading of about 75 degrees from eastern MA, as best as I can
determine on a Hi-Z 8 circle array. I made a video of its spectrum as
captured on my Elecraft P3 and posted it on YouTube:
https://www.youtube.com/watch?v=nwe0zp2XiuY.
73, John W1FV
_
Topband Reflector
Hi Mike,
I have a dual-band 160/80 meter vertical system that is based on 1/4-wave
verticals on 80. I switch in loading coils to make them work on 160. The
160 capability was added as an afterthought, a few years after it had been
set up for 80. Perhaps top loading would be somewhat more
I have studied quite a bit of the history of polar exploration and I don't
think there is any correlation between solar activity and the launching of
polar expeditions. Multiple expeditions were undertaken to discover the
Northwest Passage, the North Pole, and then the South Pole throughout the
There are niche applications, called antenna remoting, where photonic and
fiberoptic technologies are used to transmit RF signals from an antenna to a
remote receiver. You can buy commercial systems to do this. I once
designed such a system for a government application to send RF signals from
Go to http://exax.net/index.html and scroll down the page to center fed
steerable wave antenna. The diagram shows how you can feed a 2-wire
Beverage in the center, or anywhere along its length. The two transformers
in the middle have center taps that pass signal currents from one side of
the
At KC1XX we also have a 1500-foot feedline run to one of our lowband
receiving antennas. We use RG-6 with copper clad steel center conductor, but
we install a preamp right at the antenna to compensate for feedline loss and
some passive splitting losses at the station. A potential downside of a
About 30 minutes after local SR, the signal is definitely peaking SW from
FN42gk (eastern MA).
73, John W1FV
___
UR RST IS ... ... ..9 QSB QSB - hw? BK
From eastern MA (FN42gk) the signal is very strong in the daytime and
nighttime. This appears to indicate that the source is within groundwave
distance of me. I tried getting a direction fix this evening with my RX
vertical array that can switch in 8 directions. However, I see very little
This report on RFI mitigation may be of interest to folks here:
http://edocs.nps.edu/npspubs/scholarly/TR/2007/NPS-EC-07-002.pdf. It was
done at the Naval Post Graduate School and almost appears to have been
written for ham applications.
73, John W1FV
Some of you may be thinking of Project West Ford, conducted in the early
1960's by MIT Lincoln Laboratory (where I work now). Many millions of tiny
needles were launched into orbit to generate an artificial scattering
medium above the earth for long range microwave communications. You must
96 matches
Mail list logo
