[Lowfer] What kind of antenna ?

Michael Sapp wa3tts at verizon.net
Thu Sep 8 16:08:05 EDT 2016 

Doug: Watch the SM5BSZ "sensors" youtube videos on LF noise and antennas 
when you have the time. They are very worthwhile....

https://www.youtube.com/watch?v=C65u7Pmz7a0

73 Mike wa3tts

----- Original Message ----- 
From: "Douglas Williams" <williamsdoug1966 at gmail.com>
To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Thursday, September 08, 2016 3:59 PM
Subject: Re: [Lowfer] What kind of antenna ?


> Agreed. That would be highly improbable. Worked for me, though.
>
> On Thu, Sep 8, 2016 at 3:55 PM, Michael Sapp <wa3tts at verizon.net> wrote:
>
>> Doug: OK, Not likely everyone has the same noise environment or ground
>> conductivity....
>>
>> Mike tts
>>
>> ----- Original Message ----- From: "Douglas Williams" <
>> williamsdoug1966 at gmail.com>
>> To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <
>> lowfer at mailman.qth.net>
>> Sent: Thursday, September 08, 2016 3:36 PM
>>
>> Subject: Re: [Lowfer] What kind of antenna ?
>>
>>
>> Here are two interesting screenshots I took comparing the difference in 
>> VLF
>>> noise between having the DC coupler for my active antenna grounded at 
>>> the
>>> station end VS leaving it ungrounded. In both screenshots, the active 
>>> whip
>>> antenna is grounded at the base, which is about 50' from the house. In 
>>> my
>>> situation, it is far better to leave the coupler "floating".
>>>
>>> https://dl.dropboxusercontent.com/u/33457409/z1203grounded.JPG
>>>
>>> https://dl.dropboxusercontent.com/u/33457409/z1203%20ungrounded.JPG
>>>
>>> D.
>>>
>>>
>>>
>>> On Thu, Sep 8, 2016 at 3:12 PM, Michael Sapp <wa3tts at verizon.net> wrote:
>>>
>>> That would be my HF vertical and the local noise level is 30~40 dB 
>>> higher
>>>> on it compared to the ground isolated EWEs...
>>>>
>>>> Mike tts
>>>>
>>>> ----- Original Message ----- From: "Douglas Williams" <
>>>> williamsdoug1966 at gmail.com>
>>>> To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <
>>>> lowfer at mailman.qth.net>
>>>> Sent: Thursday, September 08, 2016 2:49 PM
>>>> Subject: Re: [Lowfer] What kind of antenna ?
>>>>
>>>>
>>>>
>>>> Have you tried just throwing a wire out the window and using that?
>>>>
>>>>>
>>>>>
>>>>> JOKE! ;-)  That's an interesting system. I'll have to study it some 
>>>>> more
>>>>> and read up on EWEs.
>>>>>
>>>>> On Thu, Sep 8, 2016 at 1:55 PM, Michael Sapp <wa3tts at verizon.net>
>>>>> wrote:
>>>>>
>>>>> Doug: Essentially orthogonal EWEs
>>>>>
>>>>>>
>>>>>> https://www.dropbox.com/s/xw0flkh343xhamg/LFMFEWE.JPG?dl=0
>>>>>>
>>>>>> https://www.dropbox.com/s/5ygrqqv624c73y7/ewegnd.JPG?dl=0
>>>>>>
>>>>>> https://www.dropbox.com/s/x0hu6b30w9gu694/feedsys.jpg?dl=0
>>>>>>
>>>>>> A couple brief notes...
>>>>>>
>>>>>>    The ground return wires between each end of the EWE antenna 
>>>>>> improves
>>>>>> ground resistance stability and is essential for being able to switch
>>>>>> antenna directions from the shack position by swapping rx input and
>>>>>> termination resistor. For the same reason the 10:1 transformers at 
>>>>>> the
>>>>>> antenna require a common ground or the receive direction will not
>>>>>> switch
>>>>>> by
>>>>>> swapping the rx input and termination resistor.
>>>>>>
>>>>>>    The background noise improved noticeably when I added the 
>>>>>> mid-point
>>>>>> ground on the feed lines. The two feed lines to the isolation
>>>>>> transformer
>>>>>> in the shack have their outer jackets tied together at the isolation
>>>>>> transformer input. That noticeably lowered AM BC surface wave energy 
>>>>>> as
>>>>>> measured with an O-scope. With those parallel feed lines having the
>>>>>> outer
>>>>>> jackets of the coax separate I was able to measure a few hundred
>>>>>> millivolts
>>>>>> of AM BC energy between them at the isolation transformer input.
>>>>>>
>>>>>>    The background noise improved when I added the perimeter ground 
>>>>>> wire
>>>>>> around the square area defined by the orthogonal EWEs.
>>>>>>
>>>>>>    Cleaning and oiling the ground connections a few times a year 
>>>>>> seems
>>>>>> to
>>>>>> be worthwhile for maintaining antenna performance. I do the sealing
>>>>>> current
>>>>>> treatment once a week or so to keep the loop resistance low for each
>>>>>> feed
>>>>>> line run...(the emf blasts away the thin oxide on the F connector and
>>>>>> antenna switch contact surfaces )
>>>>>>
>>>>>>   Sorry if TMI ~:) Mike wa3tts
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ----- Original Message ----- From: "Douglas Williams" <
>>>>>> williamsdoug1966 at gmail.com>
>>>>>> To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" 
>>>>>> <
>>>>>> lowfer at mailman.qth.net>
>>>>>> Sent: Thursday, September 08, 2016 12:14 PM
>>>>>> Subject: Re: [Lowfer] MM lowfer beacon update
>>>>>>
>>>>>>
>>>>>> What kind of antenna are you using, Mike?
>>>>>>
>>>>>>
>>>>>>> On Thu, Sep 8, 2016 at 10:10 AM, Michael Sapp <wa3tts at verizon.net>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Garry: I heard CFH on 76.2 last night but nothing from XND.  Noise
>>>>>>> level
>>>>>>>
>>>>>>> was about constant S6 from a local source when I checked this AM
>>>>>>>> daylight.
>>>>>>>> Not much chance of hearing XND through that kind of noise wall... 
>>>>>>>> now
>>>>>>>> and
>>>>>>>> then the local noise turns off and I have S1 or so noise level when
>>>>>>>> no
>>>>>>>> lightning static is around, but even that lower background noise
>>>>>>>> seems
>>>>>>>> like
>>>>>>>> an order of magnitude higher than what I have on 137 kHz. I did the
>>>>>>>> AC
>>>>>>>> voltage measurement on the speaker output the other day on 75 kHz
>>>>>>>> with
>>>>>>>> a
>>>>>>>> trusted analog meter with the ALC off and pretty much confirmed 
>>>>>>>> that
>>>>>>>> 10
>>>>>>>> dB
>>>>>>>> "by ear" perceived noise difference between 75 kHz and 137 kHz. 
>>>>>>>> Seems
>>>>>>>> like
>>>>>>>> I have broadband noise sources 10~15 kHz wide either side of 37 
>>>>>>>> kHz,
>>>>>>>> 60kHz, and 75 kHz....  This noise source or sources is coming in on
>>>>>>>> the
>>>>>>>> antenna as my converter is dead quiet with no antenna signal input.
>>>>>>>> My
>>>>>>>> common mode coaxial chokes are around 12mH or so, perhaps not 
>>>>>>>> enough
>>>>>>>> to
>>>>>>>> suppress much VLF energy. The noise level is much lower on the NW
>>>>>>>> direction
>>>>>>>> versus SW but still too high for weak signal detection.  I added a 
>>>>>>>> 2
>>>>>>>> x
>>>>>>>> 3
>>>>>>>> ft
>>>>>>>> aluminum earth capacitor plate at the feed line midpoint ground but
>>>>>>>> that
>>>>>>>> did not help much. I suppose I should be grateful with being able 
>>>>>>>> to
>>>>>>>> hear
>>>>>>>> reasonably well on 137, 185, 485 kHz and most of the LW BC and NDB
>>>>>>>> bands...but it would be nice the solve the VLF noise issue...
>>>>>>>>
>>>>>>>> I did not check for MM or WM overnight, I'll have to give that
>>>>>>>> another
>>>>>>>> shot some evening when the QRN is low...
>>>>>>>>
>>>>>>>> 73 Mike wa3tts
>>>>>>>>
>>>>>>>>
>>>>>>>> ----- Original Message ----- From: "N8OOU" <n8oou at meekfarm.us>
>>>>>>>> To: "Discussion of the Lowfer (US, European, & UK) and MedFer 
>>>>>>>> bands"
>>>>>>>> <
>>>>>>>> lowfer at mailman.qth.net>
>>>>>>>> Sent: Thursday, September 08, 2016 9:08 AM
>>>>>>>> Subject: Re: [Lowfer] MM lowfer beacon update
>>>>>>>>
>>>>>>>>
>>>>>>>> Garry, Thanks for the capture and report. I just looked at a 
>>>>>>>> weather
>>>>>>>>
>>>>>>>> forecast, and maybe the storms will stay North of here.  It is 
>>>>>>>> fairly
>>>>>>>>
>>>>>>>>> dry
>>>>>>>>> here, so some rain would be welcome.
>>>>>>>>>
>>>>>>>>> I have removed the "umbrella" style tophat/guywire that I used 
>>>>>>>>> last
>>>>>>>>> winter on the vertical, and put back to the Marconi style flattop
>>>>>>>>> which
>>>>>>>>> is
>>>>>>>>> supported by taller trees. I am thinking the top 3rd of the 
>>>>>>>>> vertical
>>>>>>>>> was
>>>>>>>>> shielded too much with the droopy umbrella wires. I am not sure if
>>>>>>>>> my
>>>>>>>>> new
>>>>>>>>> supports will survive the winter winds. Time will tell.
>>>>>>>>>
>>>>>>>>> In the next week or so I will move WM to the vertical, and get it
>>>>>>>>> back
>>>>>>>>> to
>>>>>>>>> normal operation.
>>>>>>>>>
>>>>>>>>> 73   de   N8OOU - Mike Meek
>>>>>>>>>
>>>>>>>>> On 09/08/2016 07:13 AM, Garry wrote:
>>>>>>>>>
>>>>>>>>> Mike, noticeable boost in SNR for lowfer MM this morning here so 
>>>>>>>>> the
>>>>>>>>>
>>>>>>>>> higher power is showing up at more than just your local receiver.
>>>>>>>>>> The
>>>>>>>>>> higher power particularly helps since storms are all around. See 
>>>>>>>>>> no
>>>>>>>>>> sign
>>>>>>>>>> of WM so far.
>>>>>>>>>>
>>>>>>>>>> Got a late start looking for WH2XND on 75 kHz WSPR-2 but because 
>>>>>>>>>> of
>>>>>>>>>> storm racket that probably didn't matter much. Had to depend on 
>>>>>>>>>> the
>>>>>>>>>> usual near-sunrise enhancement to get a few, minimal SNR decodes.
>>>>>>>>>> Interestingly, found wideband source CKN on 76.2 kHz from BC
>>>>>>>>>> active.
>>>>>>>>>> Don't see that one too often. Usually CFH is running on 73.6 kHz
>>>>>>>>>> from
>>>>>>>>>> NS
>>>>>>>>>> but it's been off the air for quite awhile now. Neither one 
>>>>>>>>>> bothers
>>>>>>>>>> reception of WH2XHR, at least not here.
>>>>>>>>>>
>>>>>>>>>> 73, Garry, K3SIW, EN52ta, Elgin, IL
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
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