[Lowfer] SIW and WM received in Georgia

Thu Feb 12 11:10:34 EST 2015

Jim (& All) : Very good on your e-probe vs loop experience. Yes, it seems to 
be the case that an e-probe, despite it's small size, requires quite a bit 
of open real estate given it's very high

gate bias resistor & input impedance condition.  My metaphor would be that 
the trees and other nearby objects have a theramin-like proximity effect on 
it --- at least with a gate resistor

 in the 10 to 22 M-ohm or higher range.  I have tried a e-probe in different 
places around my yard and anywhere near trees was the worst place to locate 
it for LF.  Seemed like I had an

 order of magnitude improvement in an open location --- but then it was too 
close to my HF vertical to be practical in my limited space situation. 
However, it seemed to work reasonably

well as a general purpose MF/HF antenna to drive my boat anchor receiver 
collection with the antenna placed between a few trees just 20ft away from 
my house.  Not optimal by any means,

but compared to the noise pickup with an indoor antenna at MF/HF, the 
e-probe does reasonably well for a non-critical application.   When I had my 
e-probe in my back yard in a more

open location, it was still about 6db noiser than my LF/MF EWE antenna, that 
is about 20 feet tall and 70 feet long.

My LF/MF EWE  has a ground wire between each of it's ground rods at each 
end, which seems to help stabilize it's reception pattern and reduce noise 
pickup....so it is really more of a loop

with the base leg on the ground and a LF/MF 10:5:1 transformer at each end 
and each vertical leg more or less somewhat proximity coupled to the tree 
trunk supporting it.   I used a single

NE/SW EWE for a few years toying with different matching transformers, 
common mode chokes, and cable grounding. Two feed lines, one to each 
transformer, listen on one transformer in

the desired direction and terminate the other transformer---usually in the 
characteristic 75 ohms but the termination value easily adjusted in the 
shack with a 75 ohm resister plus a 100

ohm potentiometer.  Basically it is one of the first WA2WVL EWE designs by 
Floyd Koontz (Feb 1995 QST p31) which I co-opted for LF/MF vs  the originaL 
160/80 meters application.

Last weekend I installed a second EWE to the NW to have some improved 
listening capability that direction and to investigate whether my noise 
environment would be reduced with a "EWE

 loop" in that orientation.  See below...

https://www.dropbox.com/s/6i0rzgwj5te2has/NWEWE.JPG?dl=0

So far the NW EWE seems to be showing lower noise pickup as it is capturing 
SIW in the low to mid -70s range whereas my SW EWE seemed to copy SIW in 
the -65 to -70 range....

Current SIW capture 
https://www.dropbox.com/s/bdkmzrzrhok2zrh/capt00001.jpg?dl=0

I started the above capture at 55/55 visual settings. Tried 45/45 around 
1529 but signal level a bit to low. Settled on 50/50 for the reminder.  I'll 
let it run until SIWs switch time and then go to .300....

Perhaps Andy will find my 2 element EWE-Tree array interesting ~:)   Like 
Jay says, just about anything will work as an LF antenna if you can manage 
the noise.....

73, Mike wa3tts

----- Original Message ----- 
From: "Jim Davey" <k8rz at etcmail.com>
To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Wednesday, February 11, 2015 1:31 PM
Subject: Re: [Lowfer] SIW and WM received in Georgia

> Thanks Mike.  Garry's reception was a welcome event for a couple of
> reasons.  Garry and I are old microwave buddies from the Chicago area.  We
> used to ragchew on 2304 and 3456 MHz quite regularly when I lived up that
> way.  Secondly, I was beginning to get pretty discouraged at the whole
> LF/MF reception quest.  When the winter season started, I was plagued by
> horrendous line noise, which has subsided considerably lately.  I can
> really sympathize with KU4XR.  I use the noise blanker in SpectraVue with
> the SDR-IQ and if you adjust the threshold, it works quite well.  Then
> when I still wasn't hearing much of anything, I began to question if the
> e-probe antenna was a very poor choice for a wooded setting.  I ran some
> careful experiments measuring daytime BCB station field strengths back in
> December that showed that a long 3m whip I was using up until then worked
> far worse when there were trees nearby than a short 0.5m whip which got me
> to within a dB or two of theoretical FS.  Three 16" diam trees are located
> within a 9-10' radius.  Naturally the question lingered as to whether a
> loop would not help in both regards.  So I threw together a 1 sq-m loop of
> 20 turns, tuned remotely to cover both 136 and 185 kHz bands, so I had
> something to compare.  Overall it seems to be much less sensitive to power
> line type noise and also seems to give better SNR over the e-probe even
> when the noise is not present.  I have to use one of Jay's 2n5109 amps on
> this small loop to see a noise rise.
>
> 73, Jim K8RZ
>
>
>
>
>
>
> On 2/11/15, 12:27 PM, "Michael Sapp" <wa3tts at verizon.net> wrote:
>
>>Nice catch Jim. Your rx system is working quite well !
>>
>>73, Mike wa3tts
>>
>>----- Original Message -----
>>From: "Jim Davey" <k8rz at etcmail.com>
>>To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands"
>><lowfer at mailman.qth.net>
>>Sent: Wednesday, February 11, 2015 12:02 PM
>>Subject: Re: [Lowfer] SIW and WM received in Georgia
>>
>>
>>> I'll post a link to the capture
>>>
>>> https://www.dropbox.com/s/tes7trqvvr7uoji/loop0050.jpg?dl=0
>>>
>>> Jim  K8RZ
>>>
>>>
>>>
>>>
>>>
>>> On 2/11/15, 11:34 AM, "Garry Hess" <k3siw at sbcglobal.net> wrote:
>>>
>>>> Just saw a nice capture from Jim, K8RZ showing lowfers WM and SIW.
>>>> Distance to SIW is about 556 miles and that's the 21st state for which
>>>>a
>>>> reception report has been received. Thanks Jim.
>>>> -- 
>>>> 73, Garry, K3SIW, EN52ta, Elgin, IL
>>>> ______________________________________________________________
>>>> Lowfer mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Lowfer at mailman.qth.net
>>>> Post must be less than 50KB total for message plus attachment!
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>
>>>
>>>
>>> ______________________________________________________________
>>> Lowfer mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/lowfer
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Lowfer at mailman.qth.net
>>> Post must be less than 50KB total for message plus attachment!
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>______________________________________________________________
>>Lowfer mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/lowfer
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:Lowfer at mailman.qth.net
>>Post must be less than 50KB total for message plus attachment!
>>
>>This list hosted by: http://www.qsl.net
>>Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
> Post must be less than 50KB total for message plus attachment!
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html 