Re: RRS - The Topic is Shortwave and the Goal is to Talk About (Write About) Shortwave related things . . .


<r2000swler@xxxxxxxxxxx> wrote in message
news:1133821838.439495.128890@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Telamon wrote:
> > Very good Terry I don't see any reason for a flames. You post good
> > information and real world experiences. What you posted above is a
good
> > example of what people reading the news group need to see in order
to
> > make educated decisions about antenna systems.
> >
> > I just add that the natural noise floor is not flat and Terry's
examples
> > above are at some particular SW frequency. If I see a good natural
noise
> > figure chart link on the web I'll post it here.
> >
> > Well, I'll just add more comment. What the information above
alludes too
> > and that is as you decrease the bandwidth of your receiver the
noise
> > floor should go down. Narrowing the bandwidth decreases the amount
of
> > spectrum that goes through the receiver and that lowers the total
> > background noise at the receiver output. You will notice that
Terry
> > references the filter bandwidth in his examples.
> >
> > --
> > Telamon
> > Ventura, California
> ---------------------------------
> The last time I ventered an opinion on splitters dxAce and others
took
> exception
> to my logic. So I decided to do some actual research. I expected
> violent disagrement.
>
> At first glance it does seem that adding 3.2dB of
> attidional attenuation in the signal path would have
> a clear negative effect on the reception of weak
> signals. When I first noticed this by direct
> experimentation, I was dubious. But after
> several tests with the weakest signal I could receive
> I decided it wasn't a fluke. After getting flamed, I
> wondered if I was misreading or misunderstanding
> what was really happening. So I decided that while
> the math showed the logic was correct, I wanted
> real world data. At about this same time I became
> convinced that the standard audio chain in the typical
> SW was at best "crap". I had doubted the
> observations at Kiwa about capacitors improving
> intelligibility of weak signals. I found that by pulling
> the audio straight off the detector diode and feeding
> it to a clean MSOFET amp, stations that were
> un-intelligible "mush" were clearer. I played with
> better AM detectors wanting to avoid the hassle
> of a synchronous detector, but in the end bowed to
> reality. I built an outboard synch detector, and with each
> improvement I found I could dig out weaker, or at least
> "mushier", stations. The remote ISM beacon started
> out as a SSB unit, but due to some drift after 3 months
> of operation I converted it to a very linear AM unit.
> Nothing fancy, I was given a Rio PMP300 with
> a 64Meg memory card. The whole project was based
> on the remote ISM test set a Radio Astronomer friend
> had used. But I wanted real voices signals, not
> "random" noise.
>
> After all my experiments I came back around to the
> observation that in most cases, the local man made
> noise floor sets the limit on reception. Better
> detectors allow you to understand slightly weaker
> signals. But the improvement, while very worth while,
> is at best maybe 6dB. And that 6dB is really optimistic
> under ideal situations. I had a AOR7030+ in my care
> for a 5 weeks while our friend arranged shipping to NZ.
> The AOR7030+ is a much better receiver then
> my R2000. And I would give a left whatever to own
> one. But inspite of the better selection of IF filters, a
> quiter RF/IF section and greatly improved detection and
> audio chain, there were very few signals that I could
> understand on the AOR and not on the R2000 with the
> added InRad 2.1KHz SSB filter.

I presume you're talking about the R2000 with the InRad
and the Sync you made working in AM? Or are you
working in ECSS?

> It has been an odd autum. We have had 3 power outages
> since the 1st of Oct and I have been home to listen
> through all three of them. The last one lasted from
> 8:00PM until 5AM. Needless to say I missed work the
> next day. It never ceases to amaze me how much the
> low level AC grunge covers, and how many very
> weak signals you can receive when the lights are out.

We had a couple of power outages, but since they were
coupled with T-storms, there wasn't much listening I
could do (safely).

I was going to ask if you're planning on playing with
small loops so that you could lower the manmade noise
floor, but I suspect based on what you wrote farther
down that that is next summer's project.

> I really enjoyed the last, long lights out event as I
> could compare my R2000s to the AOR. The AOR is a
> much better receiver, if you have a low enough local
> noise floor. Under these conditions the superority
> of the AOR stood out. It wasn't that I couldn't
> dig out most of the signals on the R2000, it was just
> a LOT harder. I am not complaining mind you, it was
> educational to see what a first class receiver can do.
> It also helped me decide to take a serious look at
> selling our place rolling the excess back into TIAA
> and moving to the sticks.
>
> The main advantage a synchronous detector offers
> is the reduced ear fatigue. With a standard diode
> detector I found that it felt like my head clogged up
> after listening to weak, nasty stations. The other
> advantage is the music we recover is mush cleaner.
> My wife plays flute and after listening to some flute
> music on a Peruvean station she admited that was
> the "cleanest SW I have heard. It sounded like the
> flutest was in the room with us." She had doubted
> the practicality of my summer long experiments. She
> had enjoyed SW but thought that distant stations
> had to sound "bad". But since it was the hottest
> summer we have had, we weren't going outside that
> much.s she thought it made more sense for me to
> play detector then antenna builder. She uses "my"
> gear in the day when I am not at home and I had to
> give her the 3rd R2000 I traded for so she can listen
> to what she wants when I am at home.

You are one lucky guy, you know that?

> The last R2000 has the AD607 synch detector
> mounted inside with a homebrew 5W mosfet AF amp.
> It sounds pretty darn sweet.

You don't have to fiddle with it at all to make it work
well? I thought that was the knock against using
something like a Sherwood: you had to fiddle with
it a bit, and if you wanted seemless operation that
was a pain in the neck.

You ought to offer mods for the R75 to make a
more effective synch there.

--Mike L.


.

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