On Sun, 21 Sep 2008, carlos2007 wrote:


This is the question:

Would you swap a Drake r8b for a Collins 51 S1? Why do I ask this?

I have a Drake R8B and a Wellbrook 1530+ antenna, and pick up a lot
ot QRM and noise S5 - 6 so I cannot do DX, I have tried with other
antennas and the result is the same.

I have read in other forums that receivers with valvel are less noiser
and one owner of the Collins 51 s1 says that QRM and noises do not
exist.

You're misinterpreting the comments.

Your problem is noise that's coming in the antenna, and the receiver
won't do a thing about that.

Even thirty years ago, there wasn't much around the average house
that generated noise. But now, just about everything is computerized
or digitized, and it all generates noise. All those switching supplies
too, they generate noise, in some cases even with the equipment turned
off. So the radio spectrum is far noisier now than in the old days.
The only places that won't suffer will be out in the country, where
there are few people to have electronic equipment around that generates
all that noise.

The noise generated in a receiver may or may not be an issue, unrelated
to this external noise problem. The noise figure of a receiver becomes
increasingly significant as you go up in frequency, while on the shortwave
bands it means relatively little since the "noise" generated by the sun
and such are less significant at the lower frequencies. Many shortwave
receivers had quite large noise figures, 8dB or so, and it never mattered,
while that sort of noise figure in the VHF range would be considered
awful; you'd want 2dB or so up there.

One confusing thing is that a cheap receiver with little gain appears
to be "less noisy" than a good receiver with lots of gain. To the
beginner, the noise coming out of a good speaker sounds bad, but
it's not. My first receiver, a Hallicrafter's S-120A (the transistorized
one) had virtually no gain, so there was little background hiss. When
I moved to an SP-600 a year later, it sounded so noisy because there
was all this hiss between stations. But the SP-600 was a much better
receiver.

Michael VE2BVW