[Milsurplus] [Boatanchors] RAK question
Richard
brunneraa1p at comcast.net
Mon Dec 25 21:42:04 EST 2017
More: First order of business is to go through your house and locate
noise sources, mostly switching supplies and some lamps. There will also
be surprises. I have a 13.8 volt supply which makes noise at LF and VLF
when connected but turned off.
Richard, AA1P
On 12/25/2017 02:36 PM, Richard wrote:
> E-Field probes aren't bad when properly located. When they're
> shadowed by trees or buildings they don't hear much. I put one 200
> feet into the woods to get away from noise, and it sort-of worked. I
> moved it to the back of the yard but under trees and it was no better.
> Then I put it in the middle of the back yard, and it was worse, being
> shadowed by trees and the house. Now it's five feet above the house
> and works pretty good. Comparing it to a random wire, performance is
> about the same at MF, but as frequency goes down the wire becomes
> quieter, and the probe soldiers on. My probe hears SAQ on 17.2 Kc
> about as well as the 500 foot Beverage, maybe better. On the random
> wire nothing. I also have a tuned loop, 3.5 feet on each side, which
> works well, but picks up noise from the house wiring. That RF quiet
> location must be next to the Fountain of Youth - may I find both of 'em.
>
> Richard, AA1P
>
>
> On 12/25/2017 02:03 PM, David Stinson wrote:
>> re: Using the LF RAK.
>> A random wire as on HF won't do unless you are listening to strong
>> BCB signals. You'll find a great deal of common-mode and switching
>> supply noise, often to the exclusion of every other signal. For a
>> beginning, I recommend a tuned loop you can use to null-out noise
>> sources. Not as hard to make as it looks. I often use just the
>> little Palomar Ferrite Rod Loop with its little loop amplifier. Used
>> to copy the 630 Mtr experimentals with just that on my night stand.
>> Last night, I had the little loop on top of the receiver in the barn
>> and was able to copy the 486 KC carrier on a fade-up with no
>> trouble. The barn has a tin roof and tin on three sides. I could
>> hear because the loop nulls local noise.
>>
>> Others love E-Field probes. I wouldn't own one. IMHO, those who
>> praise E-Field probes, do so because they've never been in an
>> RF-Quiet location with anything else, like a ground-running beverage
>> or a tuned loop. Moreover, E-probes do nothing to reject local
>> noise. Others opinions will, of course, vary, but I'd bet coffee and
>> donuts if I could take them out on an "LF Dx-pedition" with different
>> antennas, they might throw rocks at the E-Field on LF ;-)
>>
>> Best of luck with your LF adventures and Merry Christmas,
>> Dave S.
>>
>>
>> ______________________________________________________________
>>
>
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