You have the right idea. Signal/noise ratio is all that counts.

When receiving HF, feedline loss almost never matters. The reason is
that atmospheric noise is strong, and unless a receiver is exceptionally
noisy and/or an antenna is exceptionally lossy, the atmospheric noise
will be much greater than the receiver noise.

The input to the receiver consists of the signal and atmospheric noise,
to which the receiver adds its own noise. As long as the atmospheric
noise is much greater than the receiver noise, you won't hear the
receiver noise. Any attenuation in the antenna system will attenuate
both the signal and the atmospheric noise equally, so the signal/noise
ratio, which determines what you can hear, doesn't change. Any gain
ahead of or within the receiver has the same effect.

Atmospheric noise declines as the frequency increases, so it might be
possible to start hearing some receiver noise over it as you approach 30
MHz, particularly if your receiver is unusually noisy and/or the antenna
system unusually lossy. As soon as receiver noise becomes audible over
the atmospheric noise, the rules change. Then, attenuation ahead of the
receiver will reduce the signal but not the receiver noise -- which is
now the "noise" part of the signal/noise ratio --, so it *will* decrease
the signal/noise ratio.

There's a very simple test to determine whether reducing the loss will
improve your ability to hear signals. Tune your receiver to a spot with
no signals in the frequency band of interest. Turn up the volume so you
can clearly hear the background noise. Then disconnect your antenna(*).
If the noise decreases, it means that atmospheric noise is dominating,
so reducing loss won't help the signal/noise ratio. If the noise doesn't
decrease, you're hearing receiver noise with the antenna connected and
you'd benefit by reducing losses ahead of the receiver. You'll probably
find that the noise will decrease by quite a few dB when you disconnect
the antenna, and this represents the amount of loss you can add before
your ability to hear signals suffers.

When receiving HF, about the only way you can improve your signal/noise
ratio is by using a directional antenna. This will reduce the
atmospheric noise coming from unneeded directions. Particular kinds of
antennas can also improve the signal/noise ratio if the dominant noise
is man made and coming from a nearby source.

(*) In a really marginal case, you might need to replace the antenna
with a dummy load for this test -- an ordinary small 47 or 51 ohm
resistor will suffice -- but it usually isn't necessary.

Roy Lewallen, W7EL

Robert11 wrote:
Hi,

Just getting started with all of this, and want to say a quick thanks to
everyone for all the help.

Another question:

Am I interpreting this more or less correctly:

Looking at all the different types of coax available.
Will be for a receive-only HF antenna.
Antenna will have to be in the backyard about 150 feet or so from house.

The db losses are beginning to add up; at the upper limit of my interest of
30 MHz
we are getting close to around 3.5 db or so.

Is it correct for me to say that the actual losses really aren't all that
significant or meaningful,
and that a good receiver, which I have, can easily make up for them ?

That the only thing of real concern would be the S/N ?

What are the caveats to my statement above ?

Thanks,
Bob