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"Michael" wrote:
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"Michael" wrote:
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"Michael" wrote:
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In article ,
Tony Meloche wrote:
dxAceŠ wrote:
Michael wrote:
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Michael wrote:
"starman" wrote in message
Can you give us some examples of the weak
signal stations you receive on the R-75 with
ECSS? What kind of antenna do you use for these
DX stations?
Thanks
DX'ing weak signals have just as much to do with
"conditions" as they do with the power and
distance of the transmitted signal. It may be
very easy to get say...RNZI from my location
during times of the day and year when conditions
are good for it, and impossible to pick it up
during other times.
I've used ECSS to identify weak carriers too but I
was wondering what you would consider a good DX
catch. What have you heard lately that you would
classify as weak DX, given all the "conditions"
Half of what I listen to is dx, including hams from
around the world. If you need a single example, I'll
say .. How about right now.... 21:50 UTC on 7.190
.... I'm listening to what I think is Tunisia.
Currently Arabic music. The signal is barely s-3 and
it is quite noisy. The same exact signal is also
being broadcast on 7225. Still a bit noisy with fade
out, but it makes it all the way up to s-7.
I'd call this DX, but not a VERY weak one. It is far
away, and it is messy. The drill here on this signal
is to use all the tools at my disposal to clean it up
and see how good I can get it to sound... IE: ecss,
filters, gain, nb, nr... etc.....
About S8 here on both frequencies.
Steve Holland, MI Drake R7, R8 and R8B
To be fair, though, Steve - that probably has as much or
more to do with your antenna farm (I've seen the pics and
read your description - it's terrific) as it does your
reciever.
Steve does have good antennas but the Drake R8B is very
sensitive.
One thing about different manufactures is their attitude
toward specifications. Some rate their product more
conservatively than others. Just something to keep in mind
perusing the specifications between different manufactures
of radio equipment.
I don't think the difference between him picking it up on
7225 as s-8 and me picking it up as s-7 is enough of a
difference to base it on his receiver being more sensitive.
It is hardly any difference at all. If I checked the meter
ten seconds later, mine might have been at s-6 or s-9 the way
it was coming in and out.
The Drake R8B and Icom R-75 have about the same sensitivity so
I don't think that is the difference.
One real question here... And one that I'm interested in....
Why would I get it on 7190 at only s-3 while he gets it as
s-8 ??? We're both getting it about the same strength on
7225, so why should we be getting such a measurable
difference on 7190 ??? I'd say it probably has more to do
with the peculiarity of our locations in respect to the
transmitter and whatever comes between them rather then our
receivers.
The signal in question is from the other side of the world
compared to the difference in distance between the two of you
is small so location is not likely the answer.
Lots of other possibilities here.
The sensitivity numbers for the receivers are general numbers.
The actual sensitivity changes with frequency because the front
end of the radio is not completely flat. Could be your R-75 has
a bigger reflection at 7190 but this is not the likely reason
either.
Most likely the antenna itself or whatever you have for
matching it to the coax is the reason. Your antenna system most
likely has a poorer response at 7190 compared to Steve's
system.
I tried both my dipole and my 200 ft roof wire on both signals
and both of my antennas received the signal on 7190 substantially
weaker then that on 7225. I bet if you set Steve's antenna and
receiver up here at that time, you'd get the same difference in
the two signals. I don't think it is the antenna or the receiver.
Something else is going on. I know both Steve and I are in North
America, but, we are far enough away (NJ vs. MI) to have our
locations effect how we receive the signal. For all I know, the
7190 signal comes out of a different antenna set up that just
happens to be favorable to Steve's direction. I think that is
where the real study is here. To find out what difference if any
that there is between the two signals. Are they coming from two
different antennas ???
Michael, you and Steve are not far enough apart for another hop
through the ionosphere so you are about the same reception distance
from the source.
It most likely has something to do with an adverse reactance in
your antenna / matching unit / coax to your radio.
The same reactance with two totally different antennas each with its
own matching unit and coax ???
If they are similar yes.
I'll try my portables on it tomorrow. That will rule out the
antennas. An example of how less then a thousand miles can make a
big difference.... When WBCQ on 7415 went "long" on occasion, I could
barely hear it in NJ, while it was being heard well in the southern
states (further from the transmitter). It is not just a matter of a
"hop" in a lot of cases.
WBCQ is a different situation. You are not far from WBCQ (less than one
hop) as opposed to several from the other side of the planet where beam
heading is less important.
--
Telamon
Ventura, California
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