[Elecraft] K3 on 50 MHz - noise and possible harmonics

[Steve Lund]

Well great success on the ferrite core experiments today.

I aimed my yagi directly at the house, which are separated by approximately
40'. The 24960 signal was around S5-6. I wrapped 9 turns of the LAN cable
going to my old XP computer around a 2.4" #31 core. The signal dropped to
S0 - still lightly audible. The one at 24900 was completely gone. The 6m
ones also dropped to the S0 - lightly audible. I have more cores, but my
other LAN cable going to my newer Win7 machine is too short to wind any
turns around the core. Disconnecting power to the wireless router
completely removes all spurious signals on 6m. So, I know I can make
improvements, but for now it is livable.

The home theatre system audio problem was totally fixed. The right surround
channel was totally overloaded by anything more than 150w on 20m. Because
the connectors on the audio cable would take time to remove, I wrapped 9
turns around the 'Biggest #31 clamp on'. No trace of interference at 600w.

So, a big thank to Jim, K9YC, for his tutorial (and experiments) on curing
RFI.

Steve, K6UM

On Mon, Jun 29, 2015 at 9:26 PM, Steve Lund <k6um.elist at gmail.com> wrote:

> I have all these spurious signals in my K3, too.
>
> They are caused by my wireless router. But are the result of using wired
> connections to my office computers. When I remove the LAN cables these
> signals disappear, along with many on the hf bands.
>
> I have received the ferrites recommended by K9YC. The plan is to install
> them on Wednesday. I have both the #43 and #61 material.
>
> Steve, K6UM
>
> On Mon, Jun 29, 2015 at 7:43 PM, Chris Hallinan <challinan at gmail.com>
> wrote:
>
>> I've been playing around with 50 MHz USB/CW down at the low end of the
>> band
>> with a plain ol' dipole.  I'm curious about noise and birdies and other
>> people's experience, as I really don't know what to expect.
>>
>> I have a steady S3/4 noise level at all frequencies with the preamp off,
>> jumping to solid S5 with the preamp engaged.  I have several strong
>> signals
>> (probably harmonics of some interference??)  as follows listening in USB
>> mode, preamp off:
>>
>> 50.026: S4
>> 50.057: S6
>> 50.087: S5
>> 50.117: S6
>> 50.148: S6
>> 50:178: S4
>> and more as I tune up. Notice the 30KHz spacing.
>>
>> These are all steady 2-tone signals with perhaps a couple hundred hertz
>> difference in the two tones.  No variation with day/night or propagation
>> as
>> far as I can tell.  They all disappear when the antenna is disconnected.
>>
>> First, is my background noise level local or should that be expected on 50
>> MHz?  And what are these signals spaced every 30 KHz or so?
>>
>> Could this be broadcast overload way up here on 50 MHz?  I do have a
>> fairly
>> close 1580 KHz AM station broadcasting 1100 watts during daytime, and 110
>> at night, but I use an Array Solutions BCB filter.
>>
>> What have others experienced?
>>
>> Thanks and 73,
>>
>> Chris
>> K1AY
>>
>>
>>
>>
>> --
>> Life is like Linux - it never stands still.
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>
>