[Elecraft] Re: magnetic fields and phase noise?

[N2TK, Tony]

My K2/100 sits on top of my TS950SDX. If I go above about 30-50W with the K2
on 80 and 160M I have to reset my router. Was using a Belkin router. Now
using a Netgear wireless router. Both cutout. This doesn't happen all the
time - maybe 50% of the time. Been wrapping ferrite on everything, but no
difference so far. Swapped the coax cables between the 2 rigs. Router is
about 4' from the K2. I can run 100W with 950 without any problems. My amp
is in the basement about 8' away. No problem when using it with the 950 and
no problem with the K2 as long as I keep the power of the K2 below about
30-50W. Might have to move the K2 farther away and see if problem persists,
although it will be a pain to do that. Not sure yet if problem is definitely
the K2.
N2TK, Tony


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net]On Behalf Of Earl W Cunningham
Sent: Saturday, March 19, 2005 9:28 AM
To: g4bjm at hotmail.com; dbarker at visioncomm.net; elecraft at mailman.qth.net
Subject: [Elecraft] Re: magnetic fields and phase noise?

Fraser, G4BJM wrote:

"Interesting Earl, the non exhaustive tests I've done indicate that it is
not due to magnetic fields."
----------
When I first told Elecraft about this problem, they sent me the new
shield for the KPA100, which didn't help.  Then they sent a mod kit that
had to do with reducing spurious RF, which didn't help.

Then I eliminated the KPA100 as being the culprit by removing it (and
installing the original cover).  Driving the amp (with only the 10 watts
available) resulted in the same problem.  Clean when barefoot (as is the
KPA100).

Then I manually keyed the amp (instead of using the KPA-100's key output)
-- no change in problem.

Then I brought my K2/100 over to a friend's QTH and tried it with his amp
-- same problem.  Separation from his amp was 6 feet.  His amp is an
Alpha 99, mine is an Alpha 76CA (both have hypersil HV transformers).

Then, at my home QTH, I set up the K2/100 in an adjacent room and ran a
coax from it to the amp in the ham shack -- no trace of the problem.

All tests were done on CW, monitoring the transmitted signal on another
receiver (FT-1000MP) using narrow (250 Hz) bandwidth.  The problem sounds
like noise on the sidebands of the transmitted CW signal extending out at
least +/-5 kHz from center freq.  There's no reason to believe that this
problem does not also exist on SSB.
==========

"But if indeed that is the case, there must be a relatively easy, if
perhaps not elegant, way of significantly improving this."
----------
It has been suggested that mu-metal shielding might alleviate the
problem.  I'm considering making mu-metal bottom and side covers for my
K2.

Another ham (W4FMS) told me he had the same problem with his K2/100 and
Alpha 87A amp.  He found that placing an aluminum cookie sheet between
the K2 and amp with only 3 feet of separation resolved the problem.

All things point in the direction of a K2 problem that is not phase
noise.

73, de Earl, K6SE
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