RadioBanter - Icom R75 vs. R8B

"Michael" wrote in message
et...

"Telamon" wrote in message
...
In article ,
"Michael" wrote:

"Telamon" wrote in message
...
In article ,
"Michael" wrote:

"Telamon" wrote in
message

...
In article ,
Tony Meloche wrote:

dxAce© wrote:

Michael wrote:

"starman" wrote in message
...
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
what
ever
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 ???

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.

Michael

NOTE: ALSO POSTED IN A NEW THREAD ABOVE "7190 & 7225 TUNISIA...."

06/03/04 @ 21:50 UTC

Done with R-75 and 200ft "FRANKENSTEIN"

7190; In am mode there is moderate noise and fade out. There is also a
serious heterodyne or some kind of IF causing a groan/whistle on the usb.
Signal from a low of s-3 to a high of s-8 in am. LSB is nice and clear.
Peak modulation brings it up to a max of s-6 in LSB. It is still a bit
noisy but some nr helps enough to make it practical to listen to in lsb.

7225: Solid in am mode and a fair bit cleaner then the 7190 signal. In am a
low of s-6 to a height of s-8. Good in both lsb and usb. In ssb at peak
modulation it is also a max of s-6.

I tried my PL-550 and my KA-1102 on both signals using the Tecsun external
reel antenna and found that neither radio is doing a good job of dealing
with it. Both are nothing but LOTS of noise on 7190. On 7225, you can hear
it on both radios, but it is noisy as all get out. Usually, I find that my
portables can hear most of what my R-75 can hear, but it this case, they
cant.

Clearly, 7190 has problems making it here clearly for one reason or another
compared to 7225 that is doing well on the R-75. Despite that though, in
ssb on the R-75, even though 7190 is more noisy, both come in at a max of
s-6 when they are in ssb.

Michael