30 meter gain

[srife]

        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.

        Also, do any of you notice these noise waves that float across the
bands? I don't know what the official name for them are (if there is one),
and that is the only thing I could come up with. They appear to be about 6
to 8khz wide.  

Stan Rife
W5EWA
Houston, TX
K2 S/N 4216
 

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

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.
>

--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.432 / Virus Database: 268.15.15/580 - Release Date: 12/8/2006
12:53 PM

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Ken Kopp-2]

The noise you hear "floating across the bands" - MIGHT- be one
or more ionospheric sounders.  These are transmitters that send
high-power signals ... usually straight up ... into the ionosphere.

They usually sweep upward from frequencies below the BC band
into the higher HF regions and can be heard as their signals pass
through your receiver's bandpass.  One long-running system is
located on the grounds of the NBS in Boulder, CO.

There are many, many ... hundreds .... of these systems located
around the world and most are on the air 24/7.  Some play an role
in how SWBC, governments, the military and other users of the HF
spectrum choose what frequencies to use at a given time of day.  
Others are pure research operations.  One, at Weber State in northern
Utah caused much consternation on 75M several years, until a SLC
ham tracked it down and knocked on the door, so to speak.  The
operator had never heard of ham radio or knew anything about
frequency assignments.  

Most of the operators of these systems have little knowledge ... or
care about ... the HF spectrum beyond their own particular project.

Most systems today are digital and very advanced.  They spurt a
short burst of data and then hop off to another frequency within
their sounding range.  A burst from one of these systems ... if you
happen to hear it ... can be best verbalized as "brack, brack, brack,"
for perhaps two or three seconds.

Touch-lamps are another source of "strange" noise ... often in the
80/75M region.

Googe; "Ionospheric Sounder" for more info ....

If you hear noise from the sun, it is a broad-band rushing noise ...
white noise ... that may rise and fall slowly.  I used to work at the
University of Colorado's radio astronomy installation in the mountains
west of Boulder, where we operated the western hemisphere's largest
solar interfermeter, with antennas a mile apart.

73! Ken Kopp - K0PP

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Jeff-229]

I'm sorry to go off-topic, but is there a particular model of wireless
router that produces little or no HF noise?

Stan's, W5EWA, comments about his high noise level on HF got me started
looking for possible local contributors to my own noise level, which had
recently increased markedly.  I have found two sources, thus far:

Noise source 1:  My non-wireless Linksys BEFSR41 EtherFast Cable/DSL Router
with 4-port switch, which I started using a few days ago, produces very
strong broadband noise on HF.  I had only one PC connected to the router, so
I don't really need the router at present, but I had heard that having a
router between the cable modem and the PC reduces the likelihood that
someone will be able to hack into the PC via the Internet.  Is this true?
It did seem that my ZoneAlarm firewall reported fewer access attempts while
the router was in the loop.

Two of my family members plan to acquire laptops soon, which will force me
to install a wireless router, although it won't have to be located in my
shack.  So, please let me know if there is a type of wireless router that
seems to produce less HF interference.

Noise source 2:  My MFJ-4225MV switching power supply produces a very
rough-sounding heterodyne that often drifts across my operating frequency.
I noticed it on 80 meters, but it probably happens on other bands, as well.
Although switching power supplies are notorious for producing HF crud, I
would have naively assumed that any power supply designed primarily for the
ham market would be interference-free, but this is obviously not the case.
Anyway, I'm now using a Ten-Tec 937 linear supply, in place of the MFJ unit.

Please note that you may have better luck with the Linksys and MFJ units
than I've had -- I'm currently using an indoor antenna, which inevitably
maximizes pickup of crud from my various indoor devices.  The interference
from the MFJ power supply was not strong, so one might not hear it at all,
if one were using a coax-fed outdoor antenna.

Oh, I do have one on-topic comment:  I found that the K2's internal battery
makes searching for in-home noise sources very quick and convenient!

Anyway, I'm happy to report that my HF noise level is now reasonable, and
I'm on the air!

73 & 72,
Jeff
WB5GWB -- Soon to be replaced by a vanity call with a "2" in it, I hope!
Long Island, NY

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Graham Haddock]

Based on some of the comments on this email reflector in the last week,
I went hunting for noise this weekend and discovered the worst offender
in the house was the switching "wall wart" power supply for my Linksys
wireless router.  I will replace the "wall wart" with a linear regulated
supply
of the same rating, and I expect most or all of the noise to go away.  
The Linksys
box puts out a few spot carrier tones or birdies, which will still be
there, but the
broadband S5 hash was coming from the "wall wart."

--- Graham / KE9H
.
Jeff wrote:
> I'm sorry to go off-topic, but is there a particular model of wireless
> router that produces little or no HF noise?
>
>
> Noise source 1:  My non-wireless Linksys BEFSR41 EtherFast Cable/DSL Router
> with 4-port switch, which I started using a few days ago, produces very
> strong broadband noise on HF.    So, please let me know if there is a

> type of wireless router that seems to produce less HF interference.
>  


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Vic K2VCO]

Graham Haddock wrote:

> Based on some of the comments on this email reflector in the last
> week, I went hunting for noise this weekend and discovered the worst
> offender in the house was the switching "wall wart" power supply for
> my Linksys wireless router.  I will replace the "wall wart" with a
> linear regulated supply of the same rating, and I expect most or all
> of the noise to go away.

These things are a plague, and they are becoming more common every day.
  New monitors, printers, networking devices like routers and modems,
high-intensity lamps, and who knows what else all come with them.  I
counted four of them in our home office alone.  Some have FCC labels and
some do not.  A *really* bad idea whose time seems to have come!
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com