[Lowfer] WM in EN90xn, SIW still way up from normal

Sun Dec 7 16:58:38 EST 2014

Mike --  Mni Tnx for your WM efforts, the enhancement did make for an 
exciting early morning here. Went to visit a tech friend nearbyu a pickup
 my old impedance bridge -- turns out those 47uH+2.2uH molded inductors have 
a Q of only 20 and the T61's Q of 120, so the
upgrade should be noticeable.  I see DK7FC back on 136.172 this evening, 
time to melt some solder and do a rx cal here....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: Sunday, December 07, 2014 4:35 PM
Subject: Re: [Lowfer] WM in EN90xn, SIW still way up from normal

> Mike - TTS;
>
> Thanks for the later captures and filter info.  I can only praise the 
> Propagation Gods for looking favorably upon us today.  In looking at the 
> captures, while Wm is consistently weaker than SIW, we seem to be tracking 
> together in the peaks and fades.
>
> Mike - OOU
>
>
> 73   de   N8OOU - Mike Meek
>
> On 12/07/2014 10:34 AM, Michael Sapp wrote:
>> Mike & All: Still receiving light traces of WM here in daylight and SIW
>> continues way above average as I usually require QRSS60 for
>>
>> a reasonable daylight copy of SIW....
>>
>> https://www.dropbox.com/s/ehtgg2owa0gy8g2/capt00029.jpg?dl=0
>>
>>
>> No cover on the 300kHz filter as it is still in progress. I used mold
>> chokes on the center two inductors (vs T61-50 inductors on the outer two
>> inductors ) and the low Q was
>> evident when I did a performance test from 50kHz to 1 Mhz with my signal
>> gen and RF voltmeter... I should have those two molded inductors
>> replaced this evening or the next day with appropriate T61 core
>> inductors.  My isolation xfmr is wrapped in foam and then a mu-metal
>> shield. Not sure if shielding 1/2 inch leads to the BNC connectors would
>> help much --- I suppose a mag shield in the form of a steel plated
>> outlet box would not hurt. The in-shack transmission line chokes are in
>> a mag shield box with ground-isolated BNCs....remainder of my converter
>> is modular in aluminum Bud boxes
>>
>> Here are the remainder of the early thru mid - morning captures...
>>
>> https://www.dropbox.com/s/idvvjtm14ue9cy0/capt00018.jpg?dl=0
>>
>> https://www.dropbox.com/s/fzfns9txi9jj2tr/capt00019.jpg?dl=0
>>
>> https://www.dropbox.com/s/c38sixwqtb9ydci/capt00020.jpg?dl=0
>>
>> https://www.dropbox.com/s/mi83vvwor6fw3ne/capt00021.jpg?dl=0
>>
>> https://www.dropbox.com/s/5ja959eh5d687cf/capt00022.jpg?dl=0
>>
>> https://www.dropbox.com/s/8zkaiiwbn5ab1em/capt00023.jpg?dl=0
>>
>> https://www.dropbox.com/s/cxa56wqaljpz638/capt00024.jpg?dl=0
>>
>>
>> Isotemp LO & RAY6 converter....
>>
>> https://www.dropbox.com/s/k7qg6t6s7wsq84n/IMG_4145.JPG?dl=0
>>
>> (Isotemp 3.0MHz OCXO, Mini Circuits RAY6 DBM (10kHz>50MHz RF IN, level
>> 23), W1VD 2N5109 LF design preamp, & single-ended Norton 2N5109 as the
>> +23dBm LO driver at 3MHz)....
>>
>> 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: Sunday, December 07, 2014 7:07 AM
>> Subject: Re: [Lowfer] WM in EN90xn
>>
>>
>>> Mike - TTS,
>>>
>>> Thanks for that great capture. I would say that it is the result of
>>> mother nature, and your filters.
>>>
>>> I tested some changes in the Wm Helix Box yesterday which took the
>>> beacon up and down during the day. I experimented with different
>>> wiring configurations by adding in a re-wound AM BCB ferrite rod as an
>>> adjustable inductor.
>>>
>>> My results ended up being net losses, so I restored the Box to my
>>> original configuration.  I am back to the same operating parameters I
>>> have been using for the past couple weeks.
>>>
>>> I am curious to know if you have the filters open just for the pix, or
>>> will they be open all the time?
>>>
>>> When I first got the "ham-it-up" converter I experimented for 3 or 4
>>> weeks trying different things to be happier with it's performance.
>>> Most of the work was putting various filters on it's input. That did
>>> bring the performance level up to something acceptable, but killed the
>>> concept of it being a "wide band" receiver.
>>>
>>> Mike - OOU
>>>
>>> 73   de   N8OOU - Mike Meek
>>>
>>> On 12/07/2014 03:58 AM, Michael Sapp wrote:
>>>> Mike & All:  Best capture here yet of WM and at QRSS30 nornal this
>>>> time....
>>>>
>>>> https://www.dropbox.com/s/9b1cd6nipf4jt3h/wmq30.jpg?dl=0
>>>>
>>>>
>>>>      Not sure if how much of the above capture is band enhancement,
>>>> as I built a new 9th-order Butterworh 300kHz LPF this evening and
>>>> have it in line.  I am noticing a lower background noise level at the
>>>> watering hole and at 137kHz. Seems like the MF~LF converter has more
>>>> head room with
>>>> more LPF roll off in the AMBC band...
>>>>
>>>>     https://www.dropbox.com/s/r1ile71ugrqergn/IMG_4143.JPG?dl=0
>>>>
>>>>
>>>>      A few days ago I started experimenting with adding a few roll
>>>> off caps to my 75>50 Ohm isolation transformer. The
>>>> 50 ohm side is about 600uH and I found that switching 10nF and 22nF
>>>> caps across the 50 ohm secondary did a reasonable
>>>> job off reducing my AMBC overload (the LF EWE has relatively high
>>>> signal levels from the local BC 50KW stations ) that remained
>>>> with my existing 500kHz LPF.
>>>>
>>>>   Of course, an impedance matched solution is preferred, so I went to
>>>> the AADE program and toyed around with various LPF designs until I
>>>> found one I liked....
>>>>
>>>>     I'll find out soon enough if the LPF is helping the converter
>>>> performance or if we just had good LF band condx this AM.....73 Mike
>>>> wa3tts
>>>>
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