[Lowfer] What kind of antenna ?

Michael Sapp wa3tts at verizon.net
Thu Sep 8 15:55:30 EDT 2016 

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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