Mandarmoni DX
pedition IV
We were again drawn
towards Mandarmani. This sea beach resort 180 km away from Kolkata has a long
stretch of beach some 6 km and the sea side resorts still run on gensets
because there is no running electricity. Memories of our past DXpeds such as
Diego Garcia 4219 kHz blaring in our ears was enough to motivate Alokesh Gupta
the chief motivator of this DXped to make a journey all the way from New Delhi
some 1600 km away. Along with Alokesh was also C.K.Raman (VU3DJQ) from Delhi
who has an uncanny knack of zeroing on the part of the radio dial where an
exotic station is sure to be found. From nearby Kolkata there were three of us
Babul Gupta, Sudipta Ghose and I. We missed three veteran DXers Jyoti P
Chakrabarty, Jose Jacob and Tripti Ranjan Basu. Jyoti was hoping till the last
day that he could overcome his unwell health and catch up for the last part of
the DXped but that would not be. Jose was called back for work at the last
moment by his office. Commitments back home held back Tripti Ranjan Basu.
.JPG)
Like the thrill of
all DXped there were obstacles on the way. The notorious North Indian fog
delayed by five hours the Rajdhani express in which Alokesh and Raman were
travelling and it was a pity that we could not travel together from Kolkata. A
charm of DXped is the DX tete e tete, you may also call it the proverbial
"Bengali Adda ", while travelling to the site. The advance party SUV
with the Kolkata DXers carried the antenna stringing material and most of the
receivers. Alokesh and DJQ could not even make it for the last train link to
Digha from Howrah and had to catch a taxi all the way to Mandarmani.
Idea of Beverage
Masts
On the way we came
across a big store selling iron building materials by the roadside and Babul
Gupta decided to stop to look for antenna support. What we sourced turned out
to be great for DXped beverages. We picked cut pieces of building rods made of
iron some 30 mm in dia and approximately 60 cm long. These were latter hammered
on to the soft seaside soil to form foundation for the PVC pipes which were
just positioned as sleeves over the buried iron rods. We were already carrying
PVC pipes from Kolkata complete with clamp on top to secure the antenna wire.
In past we had to dig to bury the PVC pipe in the ground but the foundation was
never strong. The iron rods made the take easier. We reached Mandarmoni by 3 pm
just after the high tide had receded and cleared the beach roads .The first
thing we did on arriving at Mandarmoni was to set up the beverage support with
iron rods and PVS pipes and then string a 260 m ( North east ) antenna from
multi strand copper wire sourced from the army disposal stores. We set up yet
another antenna some 150 m over causurina trees by the sea side in the south
east direction.
.JPG)
Antenna splitter and
Baluns
We had fashioned a
decent antenna splitter this time out of a chip sourced by Jyoti P Chakrabarti
and fashioned by Babul Gupta and Sudipto Ghosh. It could support eight receiver
from one antenna. This splitter was put into use and cut out the use of alligator
clips to tap signal from the beverage to various receivers. It functioned
reasonably well. We connected the beverage to 9:1 transformer and fed in
through RG58 coax. We had elaborate testing of various homebrew baluns and
finally settled on one brewed by DJQ. But as we see later these were not enough
to cut out the noise.
Warming up
Once we fired up the
shack the South Asians started pouring in. All the Burmese station in the MW
led by 594 kHz were coming in with 576, 729 and 639 kHz in tow . AIR Port Blair
on 4760 kHz was throwing in moderate to strong signals. We could log all the
AIR MW in the direction of East West starting from AIR Dibrugarh at one end to
AIR Jodhpur at the other end. The Afro opening was fair with TWR Manzini ,
SW Radio Africa coming
in. Later the Australian regional’s on 2135 and 4835 kHz were coming through.
Early morning CK Raman caught a few Brazilians an the star of our last meet
Radio Tarma , Peru on 4765 kHz early in the morning.
Bengal Pirates, Long Wave Beacons and greetings on the amateur net
In the morning the
Bengal Pirates from Bay of Bengal came in loud and clear with their "
Jatra " style programming. By now we have got used these transmissions as
regular fixtures. Alokesh stumbled on the long wave Beacons and there were
quite a few. In early morning as we were tuning into local amateur band net on
7145 kHz LSB, we heard VU2DPI greeting our DXped all the success.
Shack on Battery only
We had genset running
in our resort only upto midnight. After that we had to rely on batteries to
power the sets. The IComs and the Drakes were running very well on the battery.
For the software support the laptops were there to last for some time. Mobile
computing came in for the first time in this meet and I was reading off my AOKI
list solely from my android phone. We were carrying three batteries but thought
that the batteries would last us for the whole of four days without charging.
That did not happen and on the fourth night we were struggling with power
supply.
Almost lost the
battle against noise.
Like the proverbial
blizzard wiping out an entire expedition team after the first night we started
losing it out to radio noise of the man made RFI type. This perplexed us
because here we were far from any electrical activity so where will the noise
be coming from ? On the first night there was thick fog from late night and by
early morning droplets of water had precipitated all along our antenna. We
wonder whether these droplets were the cause because the noise definitely
increased as the night progressed and was at its peak early in the morning. On
day two we thought that the multi stranded copper wire of our longest beverage
was pulling in more noise because of its multiple joints. We replaced the whole
of it with single stranded copper wire. We also installed the 9:1` balun but
the second night we still had to battle noise. On the third day we set up yet
another beverage directed north south and terminated it with ground via
resistors. But that too did not break the noise problem. We were still bugged
by noise as the night progressed and as the fog increased.
The breakthrough in
our battle !!!
On
the last day of our dxped we were desperate to try out something different.
That is because we were simply frustrated with electrical noise. Our multi
stranded beverage ( North South ) was not performing well. Babul Gupta was
always pushing for something different than the standard beverage antenna for
DXpeds. So we pulled it down and converted it into a huge loop by taking it
round the big water body around which our resort was built. These were
connected to two ends of RG 58 coax and fed into the receivers. That was the
breakthrough. The first sign of our success appeared when on preliminary
testing we found Myanmar on MW on 594 kHz in the peak of afternoon. It was
blaring with strong signals at a time when even the local AIR station such
Kolkata A and Cuttack normally have difficulty in transmitting upto this place.
The noise in the bands had just disappeared and did not appear even till late
in the evening. The other beverages out there were however were still picking
up noise. As the night progressed, we started tasting our success. In the 25 mb
there were a host of Brazilians and Argentinians. The Caribbean Beacon on 11775
kHz at 2113 UTC was sweet taste of success. Papua New Guniea Wantok Light radio
on 7235 kHz came in briefly at 2110 UTC. On 4750 Khz RRI Makassar was coming in
moderate to strong signals at 2130 UTC. It was all through the great loop.
Winding Up
As we were winding up
the great loop antenna, we were convinced that in our next DXpeds we should try
different antenna rather than the traditional beverage. The simple reason is
that man made RFI is becoming so overwhelming, we need to have most of our
antenna skills directed against it till we come out with the best antenna for
DXpeds. On the way back home, the whole DXped team crossed the grand gates put
up for the Mandarmani Beach festival. The beach festival was on the same dates
as our DXped. It was meant to popularise Mandarmani as a tourist destination.
But for us it meant more popularity, more tourists, more electrical noise.
Dr Supratik Sanatani (VU3IFB)
____________________________________________________________________________________________
AIR KOLKATA ANTENNA TALES
Dr.Supratik Sanatani, VU3IFB
The
super cyclone of October 1999 brought down the antenna 120 m mast of Kolkata A
657 Khz which radiated 2x 100 kw. In the words of an engineer manning the
transmitter " we got a phone call that AIR Kolkata A was not audible. When
we looked out, the main antenna mast simply was not there !! "The huge
mast built of thick gauge metal can still be seen lying in the premises.
Portions have been sawed off to make way to the newly installed 120 m mast.
This incident caused disruption of Kolkata A transmissions for few days.
Transmission resumed only when a new mast was put up.
The
new main radiating mast of Kolkata A had a parasitic mast put up few meters
down south. It was to act as a reflector and direct most of the radio signals
to the north which is the populated part of the State. The southern parasitic
mast was to avoid valuable signals getting lost in the Bay of Bengal to the
south which is sparsely populated anyway. However, a controversy cropped up in
2011. During a tropical cyclone in July 2011 few fishermen who had ventured out
to the sea were lost. There was hue and cry in the media that the disaster
could have been avoided if the weather bulletins from AIR Kolkata could be
better heard (http://groups.yahoo.com/group/bangladx/message/2668). The AIR authorities were under
pressure when news reports originating from the fishing town of Kakdwip said
that Bangladesh Betar weather bulletins were better received over the Bay of
Bengal ((http://groups.yahoo.com/group/bangladx/message/2686). The AIR authorities woke up and an
engineer was dispatched in a coast guard vessel to measure signal strength of
AIR transmissions almost 300 km deep down south in the Bay of Bengal. He found
good to strong signals all throughout the test area. However, the authorities
decided to disconnect the parasitic reflector mast to put the controversy to
rest. The parasitic mast still stands up mournfully though in the antenna field
of Chandi some 24 km south of Kolkata.
Pilferage
is another minor irritation which bugs the antenna fields of Chandi. Even
though manned by security guards round the clock,and watch towers in the
periphery the precious copper of antenna and feeder elements are prey to the
thieves. Most often the pilferages would be minor e.g. one coil of some
hundreds of tank circuits in the antenna support wires or few lengths of
concentric feeder lines. However, these would disbalance the fine tuning
required for that extra last mile for the radio signal !
Yet
another element which upsetting the fine tuning is the collapsed old tower
which is awaiting bureaucratic clearance for disposal . A mammoth steel
structure in the antenna fields is bound to add some inductance here or there
and compromise design efficiency. The same applies to the disconnected
parasitic antenna mast in the south which is still there completete with the
ground radials. This is bound to compromise the design efficiency.
The
Engineers at the site were however very upbeat. They are proud that their
signals were getting around in spite of all the difficulties and they have
faithful listeners tuning in. One engineer who had just completed a stint at
Orissa talked about a 90 year old faithful listener who would telephone the
station at the slightest fall in transmission quality. However, he would also
sympathise with the ground realtites. Talking about ground realities in India,
I was reminded of the Engineer at AIR Aligarh HPT who talked about Neel Gai's (http://en.wikipedia.org/wiki/Nilgai) charging into antenna curtains and
disrupting transmission.
Report
by Dr Supratik Sanatani after a visit to Amtala and Chandi facilities of AIR
Kolkata along with Babul Gupta, Sudipta Ghosh & Swopan Chakraborty in July
2012.
_________________________________________________
.JPG)
Like the thrill of
all DXped there were obstacles on the way. The notorious North Indian fog
delayed by five hours the Rajdhani express in which Alokesh and Raman were
travelling and it was a pity that we could not travel together from Kolkata. A
charm of DXped is the DX tete e tete, you may also call it the proverbial
"Bengali Adda ", while travelling to the site. The advance party SUV
with the Kolkata DXers carried the antenna stringing material and most of the
receivers. Alokesh and DJQ could not even make it for the last train link to
Digha from Howrah and had to catch a taxi all the way to Mandarmani..JPG)
