Posted by
Don Wilhelm-3 on
Dec 09, 2006; 3:14am
URL: http://elecraft.85.s1.nabble.com/30-meter-gain-tp441721p441726.html
Stan,
Things are a bit on the noisy atmospheric side right now, so what you are
hearing may be compounded by that, but certainly not at an S-3 or higher
levell. Of course, that has nothing to do with whether or not to use the
PreAmp on 30 meters (or any other band).
If you turn the preamp off, then disconnect the antenna - turn the gain up
until you can hear just a bit of noise - then connect the antenna. If the
noise level increases when you connect the antenna, then leave the preamp
off - turning the preamp on will be of no benefit, and in fact the dynamic
range of the receiver will be decreased under those conditions. Certainly,
having the preamp on will increase the s-meter reading, but you don't listen
to signals with the s-meter - just use your ears.
You may have a local noise condition, but the A and K index is up at this
time too.
30 meters is somewhere between the 'low bands' and the 'high bands' and has
unique propagation characteristics of its own - sometimes it behaves like 20
meters and sometimes more like 40.
Your vertical may be a big part of your noise level if you are in a
populated area - verticals will usually pick up more man-made noise because
it is usually vertically polarized. I have a quiet location that does not
suffer from local noise sources and I do not notice any more noise on a
vertical than on the horizontal antennas for any of 40, 30 and 20 meters but
YMMV. For 30 meters and my antennas I currently have an S-0 noise level
with the preamp off and an S-1 level with it on - 40 is similar.
73,
Don W3FPR
> -----Original Message-----
>
> My K2 seems to have way too much gain with the preamp on for 30
> meters, OR I have a bad EMI problem here. The noise level stays
> at 10 to 20
> over S9 with it on, and it is not useable with the noise floor that high.
> With the preamp off, the S-meter seems to sit around S3. Is this
> normal for
> 30 meters on the K2? I seem to remember the manual stating that the preamp
> was not needed on the lower bands. I thought 30 meters was
> considered one of
> the high bands (with 20m) and so I had left the preamp on for 30.
>
> I have really been plagued with a lot of noise here in the past
> several months, and I am trying to figure out if I have an EMI
> problem here
> locally. My noise level has been very high most of the time lately on 20
> meters. Only occasionally is it low enough that I can use that band. I am
> thinking that the problem is present on 30 meters as well, but just can't
> remember what the preamp setting is for that band. I seem to remember that
> the preamp was on all the time for 30 meters, but I am just not
> sure now. At
> this hour there are no sigs on 30m to tell what my receiver is doing with
> the preamp off.
>
> My antenna is a Butternut HF9V vertical that I have had for a couple
> of years. This evening I strung up a 20 meter dipole just to see
> if it would
> make any difference. I see a little improvement on 20 meters, but
> the noise
> is still S7 to S9 and 30m is just as noisy as ever with the preamp on.
>
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