[Lowfer] VLF

Wed Dec 25 16:04:59 EST 2013

Philips found that people were not buying as many of the bulbs because of the yellow color on top.  Thinking that the light would be yellow.
The newer version of the A-19 bulb has a white covering over the bulb, for better "curb appeal"  
Last week they were $ 7.95 at home depot, maybe they still are

Paulc
W1VLF

________________________________
 From: "jrusgrove at comcast.net" <jrusgrove at comcast.net>
To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <lowfer at mailman.qth.net> 
Sent: Wednesday, December 25, 2013 3:34 PM
Subject: Re: [Lowfer] VLF

Doug

Philips ... the ones with the yellow colored split top and more recently Cree. Bought them when they 
were being heavily subsidized by the state of CT. About the only benefit I can remember in recent 
times of living in the (Un)Constitution State.

My preference is the warm white (~2700k) types since they're virtually indistinguishable from 
incandescent.

Jay

----- Original Message ----- 
From: "Douglas D. Williams" <kb4oer at gmail.com>
To: "Discussion of the Lowfer (US, European, &amp,UK) and MedFer bands" <lowfer at mailman.qth.net>
Sent: Wednesday, December 25, 2013 2:57 PM
Subject: Re: [Lowfer] VLF

Jay I would be interested in what brands of LED lighting you use.

Andy, following the advice of Jack at Clifton Labs I super-glued five
Steward 40T1417-10H  DigiKey PN 240-2537-ND) cores together and wound as
many turns of RG174 through them as I could. This is my common mode choke
between the DC coupler and my active whip.

https://dl.dropboxusercontent.com/u/33457409/common%20mode%20choke.jpg

It helped to reduce noise carried along the coax shield, though that was
already minimized by Jack's excellent design power coupler which, IIRC,
isolates the station ground from the coax shield ground. So the only place
my antenna coax shield has a galvanic connection to ground is at the base
of the antenna.

Let me see if I can find a couple of pictures to illustrate the difference
at VLF.

Ah, here is what happens at VLF when I permitted a galvanic connection by
grounding the Clifton labs unit inside my shack:

https://dl.dropboxusercontent.com/u/33457409/z1203grounded.JPG

And here is the same spectrum with the unit ungrounded at the shack and the
coax shield only grounded at the base of the antenna:

https://dl.dropboxusercontent.com/u/33457409/z1203%20ungrounded.JPG

Amazing difference. These pictures were taken before I made the common mode
choke. Need to redo them and see what it looks like now.

-Doug

On Wed, Dec 25, 2013 at 10:43 AM, <jrusgrove at comcast.net> wrote:

> Andy
>
> After many years chasing VLF signals I've come to the conclusion that the
> best approach is to use the smallest antenna possible ... the main
> requirement being that the antenna should be able to produce sufficient
> 'band noise' to overcome the receiver noise. A small antenna minimizes the
> amount of  noise pickup thereby easing the noise mitigation that must be
> carried out. Small 'amplified' e probe or loop antennas are ideal for this
> application.
>
> For optimum reception, one should be prepared to try both types of
> antennas at different locations within the boundaries of receiving site.
> Picking one type and mounting it in a convenient spot is unlikely to
> produce optimum results. At this location loop antennas have, in general,
> proven noisier than e probe antennas for VLF reception. Sighting of the
> antenna (e probe in my case) was initially carried out with battery
> operated receiving equipment while roaming the property. Several favorable
> areas were identified for further investigation and ground/mast support
> rods were driven into the ground to facilitate testing at those locations.
> Further testing with the 'full blown' setup using SpectrumLab was carried
> out to identify the best location. There can be 'sweet spots' where noise
> pickup is at a minimum.
>
> In addition to selection and sighting of the antenna, noise mitigation
> techniques must be carried out. This includes isolation transformers and/or
> common mode chokes and even battery/solar power for the antenna vs. power
> over the coax. At my location conventional light dimmers and CFLs were
> removed years ago. Several brands of LED lightning are currently used and
> are rf quiet.  New arrival electronic 'gadgets' (specifically their power
> supplies) are subject to testing and replacement with low-noise
> equivalents. Transmit antennas, not necessarily resonant at the frequencies
> of interest, may have to be disconnected (left floating) to completely
> eliminate re-radiation.
>
> This all may sound a bit extreme but it is what has made the difference at
> this location. YMMV as all locations have their own individual
> characteristics. As one moves up in frequency through LF, MF and into the
> HF spectrum the noise problems typically become less making an effective
> receiving setup less critical.
>
> Jay
>
> ----- Original Message ----- From: "Andy - KU4XR" <ku4xr at yahoo.com>
> To: "1750 Meter List" <lowfer at mailman.qth.net>
> Sent: Tuesday, December 24, 2013 1:04 PM
> Subject: [Lowfer] No beeps and no SAQ here in Friendsville
>
>
> Admittedly excited, then utter disappointment..At Jays recommendation, I
> listened for the
> Alpha beeps for over an hour.. I tried every trick on hand, but not a
> single beep heard....
> As I expected; the static level did rise quite noticably as the night went
> on, but with the
> right amount of clipping, and noise blanking in Spec Labs filtering; I
> could almost eliminate
> the static bursts, except for the strong ones..  I started listening on
> 17.2 KHz with a
> 100 Hz BW, and filtering engaged, at 2:25 am EST, just after 2:30 am, I "
> thought " I heard
> a carrier come on.. From past comments, I listened to see if it drifted
> around as SAQ
> reportedly does during tune up...  No Drift.. ( disappointment starts ) ,
> with no drifting of
> the signal, probably not SAQ... I did not log the time, but " close to "
> 2:35 to 2:40-ish ,
> I again " thought " I heard a faint CW signal, and heard what I thought
> was " 73 " ...
> John Andrews - W1TAG mentioned to me in a post quite some time back, that
> the human
> brain is quite good at trying to make order out of chaos.. Mine was in
> sleep deprivation overdrive..
> By 2:45 am; nothing but static.. I anxiously waited for 3 am, had Audacity
> timer recording,
> just in case I fell asleep at the mouse... 3 am came... nothing !! around
> 3:06 am, I thought I
> heard a very faint CW note, but not above the noise enough to make out
> anything.. I started
> quickly changing settings, turning off the clipper, then the noise
> blanker.. That only clobbered
> me with complete static bursts.. I turned off one bandpass filter, still
> no signal, then the last
> bandpass filter.. I was wide open with noise.. but no signal from SAQ.. I
> was using my own
> custom user file for Spec Lab that I have spent a couple of weeks -
> peaking, and tweaking..
> As a last gasp attempt; I opened Spec Labs " SAQrcvr "  file, and listened
> for about 5 more
> minutes.. But by 3:15 am ; I knew it wasn't happening here this year
> either.. I turned
> Audacity off, and shut down, and went to bed... I have not listened to
> Jays audio file, so
> This report is what I actually " didn't hear " without trying to confirm
> something by someone
> else's reception.. Now for the Techie notes, and just for the sake of
> posting them..
> I used my 160 meter dipole, in a " T " configuration.. ran it thru a 33 mH
> choke.. I had an
> air variable with a total of .0012 µF.. Peaked amount for 17.2 KHz was
> .001 µF +/- a few pico's..
> I ran this thru a 2 section Hi-Pass Filter to lower the AC buzz.. I am not
> " scientific " , I just
> lashed up something, and then changed values until I got the best results
> from my viewpoint..
> I ran the antenna thru a .047 µF disc cap, with a 4 mH adjustable Inductor
> to ground, this
> then went thru a .01 µF cap, with a 4 mH Inductor to ground.. The variable
> inductors were
> adjusted for peak at 17.2 KHz.. L-1 had an in circuit value of 3.17 mH for
> 17.2 KHz...
> L-2 had an in circuit value of 3.26 mH... The air variable from the
> antenna to ground would
> move the resonant point back and forth, and adjusting the Inductors in the
> Hi-Pass filter
> would peak the " noise level " for the frequency I was listening on.. The
> Hi-Pass filter gave
> me a 20 dB reduction in AC Buzz,  At 6 KHz and down, it was almost gone..
> the noise
> level on 17.2 KHz peaked on Spec Labs graph with the settings I had, at
> -45 dB , and rolled
> off fairly well to about -60 dB at 10 KHz , and -70 dB at 6 KHz ..
> Naturally the roll off was not
> that sharp above 17.2 KHz, but was quite noticable on the spectrum graph..
> This arrangement
> then went into the sound card mic input ...  I had mentioned in an earlier
> post that I have the
> best VLF reception that I have had to date, and I believe that to be
> correct, even though I did
> not hear SAQ last night.. I know the military stations are " mega-powered
> " , but I have seen,
> And Heard ! audibly, stations that I have not in the past... Remembering a
> recent comment
> from Jay - W1VD; " almost any antenna will capture enough signal, and
> noise ; the issue
> is the noise " ... To be serious with this ; that must be my focus.. an
> antenna that gathers
> much less noise than my 160 meter noise catcher... I need to seriously
> consider getting
> out the wellbroop loop I have stored in the garage, and get it set up, and
> use it...
>
> Thanks for reading... And I wish all of you, a very Merry Christmas, and
> the best year you
> have ever had in 2014..
>
> 73 Friends :
>
> Andy - KU4XR
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