The WiFi transmitter in my Actiontec GT701-WG produced interference over
much of the HF spectrum and completely obliterates the 17 meter band.
With my HF receiver in AM mode, looking at the received audio with a
spectrum analyzer, I see peaks at 60Hz and 120Hz. The router and WiFi
portion work just fine.

Anybody ever run into a problem like this and found a solution to it?

I can eliminate the noise by disabling the radio in the router, but a
real fix would be preferable.

--
Bert Hyman W0RSB St. Paul, MN

The WiFi transmitter in my Actiontec GT701-WG produced interference over
much of the HF spectrum and completely obliterates the 17 meter band.
With my HF receiver in AM mode, looking at the received audio with a
spectrum analyzer, I see peaks at 60Hz and 120Hz. The router and WiFi
portion work just fine.

That's distinctly puzzing, from a frequency point of view, since the
WiFi frequency is far above HF, and the 802.11 protocol tends to use a
beaconing / timeslicing which isn't tied to the powerline frequency
cycle.

Anybody ever run into a problem like this and found a solution to it?

Consumer-grade networking gear is notorious for generating QRM. I
haven't seen this specific symptom before.

I can eliminate the noise by disabling the radio in the router, but a
real fix would be preferable.

I could imagine several paths for the interference:

- The presence of 60 and 120 Hz sideband spacing suggests that it may
be power-supply related. Possibly, the enabling of the radio is
raising the WAP/router's current consumption beyond what the "wall
wart" is capable of delivering. If the DC voltage supplied by to
the router were sagging 120 times a second, it might generate all
sorts of interesting QRM... and this might be leaking out of the
cabinet directly, or coming back out along the power cable. Or,
perhaps, a switching-supply wall wart might be emitting QRM
directly under conditions of high (but acceptable) current load.

- There might be QRM RF coming out to the WiFi antenna... but that's
a pretty good approximation of an infintesimally-short
dipole/monopole at HF and wouldn't radiate efficiently.

- The QRM might be coming from the radio itself, but leaking back out
through other paths... onto the Ethernet cables or the power wiring.

I'd tend to suspect the power supply, and QRM leakage back out into
your household AC wiring... that'd be a much more efficient path than
emission out of the WiFi antenna.

As to specific examples: I've chased down QRM problems involving two
different pieces of consumer Ethernet / wireless gear.

One was a buzzy QRM which wandered around the whole 2-meter band, and
was bad enough to get in on the squelch tails of at least two
repeaters located miles away. The cause was a 10/100-megabit hub
which was "singing" loudly - I believe it was probably a harmonic of
one of its on-board clock oscillators. The QRM was apparently getting
out into the external power wires and external Ethernet cables
(common-mode, I assume) and was being re-radiated efficiently.
Replacing the switch with one of another brand fixed the problem.

The second was a a set of closely-spaced (some kHz apart) spurs
throughout the 2-meter band, strong enough to open the squelch on an
HT or scanner. These were coming from the switching DC-to-DC
converter inside a wirelss router/switch (one of the Netgear grey-
plastic varieties). They seem to have been radiating directly out
from the PC board, as they were strongest with the probe closest to
the chassis, and did not appear to be leaking out through the DC
cable to the wall wart. The router had some ferrite beads and cap
bypassing for the DC input. Replacing the WAP/router with a different
model fixed the problem.

If your router is of a fairly recent vintage, it was probably supplied
with a switching-type DC supply... I think a lot of the cheaper ones
can be prone to be HF-noisy. You might want to consider finding
an old linear-type (transformer/rectifier/caps) supply with the same
output voltage and equal or better current capacity, and see if that
makes the problem go away.

Other possible technical fixes: wrap the DC power cord through a
clamp-on ferrite a few times, as close to the router as possible;
figure out how to construct a high-pass filter for the router's
antenna connection which will pass signals above 2 gig and block
signals below that.

If all else fails, replace the router with a different brand.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Bert Hyman" wrote in message
...
The WiFi transmitter in my Actiontec GT701-WG produced interference over
much of the HF spectrum and completely obliterates the 17 meter band.
With my HF receiver in AM mode, looking at the received audio with a
spectrum analyzer, I see peaks at 60Hz and 120Hz. The router and WiFi
portion work just fine.

Anybody ever run into a problem like this and found a solution to it?

I can eliminate the noise by disabling the radio in the router, but a
real fix would be preferable.


Try feeding power to it from a battery source, rather than the wall wart
that comes with it. See what that does for it.

Brenda Ann wrote:
"Bert Hyman" wrote in message
...
The WiFi transmitter in my Actiontec GT701-WG produced interference over
much of the HF spectrum and completely obliterates the 17 meter band.
With my HF receiver in AM mode, looking at the received audio with a
spectrum analyzer, I see peaks at 60Hz and 120Hz. The router and WiFi
portion work just fine.

Anybody ever run into a problem like this and found a solution to it?

I can eliminate the noise by disabling the radio in the router, but a
real fix would be preferable.


Try feeding power to it from a battery source, rather than the wall wart
that comes with it. See what that does for it.



I was thinking same thing. He has a swiching wall wart that responds to
the current draw when the WiFi TX is enabled.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

On Thu, 5 Jun 2008, Bert Hyman wrote:

The WiFi transmitter in my Actiontec GT701-WG produced interference over
much of the HF spectrum and completely obliterates the 17 meter band.
With my HF receiver in AM mode, looking at the received audio with a
spectrum analyzer, I see peaks at 60Hz and 120Hz. The router and WiFi
portion work just fine.

Anybody ever run into a problem like this and found a solution to it?

I can eliminate the noise by disabling the radio in the router, but a
real fix would be preferable.

One other responder suggested to try battery power to see if it is a
problem in an ac to dc power supply, but otherwise a lot of electronic
deviced these days spit out all kinds of hash, noise, spurious emisions
all up and down the RF spectrum. I have had problems with computer
emissions getting into receivers, and very often weak to strong diode
noise getting into my receivers. Sometimes you can add bypass capacitors,
inductors, and sheilding (metal foil around the device and then
alligator-clipped to a ground, or the ground hole in a three prong AC line
power outlet plug) to cut down on this. Good luck otherwise.

--
Bert Hyman W0RSB St. Paul, MN

Try feeding power to it from a battery source, rather than the wall wart
that comes with it. See what that does for it.



I was thinking same thing. He has a swiching wall wart that responds to
the current draw when the WiFi TX is enabled.

Exactly my problem with a Wirespeed DSL modem. Cheap wall wort would spew
all over the spectrum after a few minutes under load.

In news:mk22k.17746$qP.9885@trnddc03 "JB" wrote:


Try feeding power to it from a battery source, rather than the wall
wart that comes with it. See what that does for it.



I was thinking same thing. He has a swiching wall wart that responds
to the current draw when the WiFi TX is enabled.

Exactly my problem with a Wirespeed DSL modem. Cheap wall wort would
spew all over the spectrum after a few minutes under load.

Thanks for the suggestion about the power supply.

I'll be cobbling together an appropriate cable to feed the modem from a
stiffly regulated analog supply. If that works, I'll just build a little
supply to replace the wall wart.

--
Bert Hyman St. Paul, MN

In Bert Hyman
wrote:

In news:mk22k.17746$qP.9885@trnddc03 "JB" wrote:


Try feeding power to it from a battery source, rather than the wall
wart that comes with it. See what that does for it.



I was thinking same thing. He has a swiching wall wart that responds
to the current draw when the WiFi TX is enabled.

Exactly my problem with a Wirespeed DSL modem. Cheap wall wort would
spew all over the spectrum after a few minutes under load.

Thanks for the suggestion about the power supply.

I'll be cobbling together an appropriate cable to feed the modem from a
stiffly regulated analog supply. If that works, I'll just build a little
supply to replace the wall wart.

That seems to be it.

I powered the router from an Astron RS-12A and the interference was gone.

Don't know if the wall wart itself is the source of the problem or if it
drops output under load and causes the router to misbehave, but it's an
easy enough fix.

--
Bert Hyman W0RSB St. Paul, MN

In Rick Frazier
wrote:

It was an easy task to put together a decent but cheap analog power
supply with a few 3 terminal regulators to power the devices in
question,

I was surprised to find a cache of 7812s in my parts bin and even one
LM320K-12 and one LM340K-12.

and all of the hash was gone (for awhile). I don't exactly
know how, but a few of the things somehow crept back into the house,
and it's time to go on another extermination binge for the wall warts
again...

I just took a walk around the house and see that the things are
everywhere, all plugged in and probably all squawking to some degree.

--
Bert Hyman St. Paul, MN

My bet is the caps are cheap and go bad. I get wall worts for a buck at the
thrift store so it's just a matter of swapping out the bad ones. It takes a
hammer to get into them so there is nothing serviceable except the
connector.

If you go the route of daisy chaining from your main supply beware you may
have common mode issues on some bands.


"Bert Hyman" wrote in message
...
In Rick Frazier
wrote:

It was an easy task to put together a decent but cheap analog power
supply with a few 3 terminal regulators to power the devices in
question,

I was surprised to find a cache of 7812s in my parts bin and even one
LM320K-12 and one LM340K-12.

and all of the hash was gone (for awhile). I don't exactly
know how, but a few of the things somehow crept back into the house,
and it's time to go on another extermination binge for the wall warts
again...

I just took a walk around the house and see that the things are
everywhere, all plugged in and probably all squawking to some degree.

--
Bert Hyman St. Paul, MN