And to you also Mark and everyone in the group!

--- In VLF_Group@yahoogroups.com, "marky26_uk" <mdennisond@...> wrote:
>
> Happy Christmas & Happy New year to all !!!!!
>
> Mark
>

http://yo9gjx.blogspot.com/

Happy Christmas & Happy New year to all !!!!!

Mark

Thank you for the catch.
This circuit does the same thing in the analog domain that CDMA does in the
digital.

--- In VLF_Group@yahoogroups.com, "flagstaff_rich" <kc9gq7@...> wrote:
>
> This lock-in amp circuit showed up recently in EDN Magazine.  It may be of
interest to the group:
>
> http://www.edn.com/contents/images/6711860.pdf
>

This lock-in amp circuit showed up recently in EDN Magazine.  It may be of
interest to the group:

http://www.edn.com/contents/images/6711860.pdf

> I will send to you my LTspice files.

Yes, thanks. The problem I have with the Students version of
PSpice is exactly that. The number or parts in the libs is restricted.
In order to have a new one you need to throw out an old one. And I
never really managed to integrate the model as such (for the simulator) with the
graphics model (or however it is called) in the Schematics
editor. LTSpice has a different editor. And you how ....

Walter

Hi Walter,

> sorry for the late answer. Somehow I missed it.

No problems, I think I replied to a reply to you, instead of replying to you
directly :-)

> Yes the vlf.it circuit is good. However it needs a symmetric supply.

No, it does not need a symmetric supply actually. Currently I'm powering it with
a 8 x 1.2V rechargeable battery pack (stolen from one of my child's toys :-)).

Thanks to Renato Romero who is the author of the design together with Marco
Bruno.

> For the vlf.it circuit: Did you ever note resonance like frequency bands where
the amplification is higher than elsewhere?

I will send to you my LTspice files. LTspice is free from Linear Technologies
and contains models for almost all LT op-amps including the LT1028. The LT1028
is pin-to-pin compatible with the OP27 and has better overall characteristics
(gain-bandwidth product, slew rate, etc.).

> Please put an unfiltered spectrum in the files or - if of no common interest -
send via mail (fedderwi at uni-bremen.de)
OK, I will send it to you directly via e-mail.

> Merry xmas and a happy new year
Merry christmas to you and your family :-)
I'm waiting for the SAQ xmas eve on Dec, 24 at 08.00 UTC :-)

Regards
Daniele

--- In VLF_Group@yahoogroups.com, "Walter" <fedderwi@...> wrote:
>
> Hi Daniele,
>
> sorry for the late answer. Somehow I missed it.
>
> Yes the vlf.it circuit is good. However it needs a symmetric supply.
> That was the reason why I tried Peter simple transistor based approach.
>
> For the vlf.it circuit: Did you ever note resonance like frequency bands where
the amplification is higher than elsewhere?
> MY Pspice simulation shows it and I seem to observe it as well.
> Depends on the opamp(-,odel) used in Pspice. I have a Students edition
> with only limited number of different opamps.
> I tried to extend the frequency range as you described it.
> But then I had Radio Bremen medium wave at 936 kc and 15 or so km away
xmodulating.
> Please put an unfiltered spectrum in the files or - if of no common interest -
send via mail (fedderwi at uni-bremen.de)
>
>
> Merry xmas and a happy new year
>
> Walter
>

Hi Daniele,

sorry for the late answer. Somehow I missed it.

Yes the vlf.it circuit is good. However it needs a symmetric supply.
That was the reason why I tried Peter simple transistor based approach.

For the vlf.it circuit: Did you ever note resonance like frequency bands where
the amplification is higher than elsewhere?
MY Pspice simulation shows it and I seem to observe it as well.
Depends on the opamp(-,odel) used in Pspice. I have a Students edition
with only limited number of different opamps.
I tried to extend the frequency range as you described it.
But then I had Radio Bremen medium wave at 936 kc and 15 or so km away
xmodulating.
Please put an unfiltered spectrum in the files or - if of no common interest -
send via mail (fedderwi at uni-bremen.de)


Merry xmas and a happy new year

Walter

> I'm a brave taxpayer, therefore I have a right to be paranoid, eh?

How is that? If and when DHO is off air we can't talk to the
subs. But they are all in the base anyway to allow the crew for a Christmas with
the families.

I remember very well the upset people when the experimental craft
where my coworkers ran tests was scheduled to be in at
12oo hours on Xmas eve. But thats 30 years ago. So no need for
BND MAD and others to jump ouz of the sofas.

Walter

I don't know how detailed the book is, but I found a very interesting piece in
an unexpected place: http://www.fcc.gov/omd/history/radio/power.html

--- In VLF_Group@yahoogroups.com, Bob <bob.vk7zl@...> wrote:
>
> Greetings all
> An enthusiast may be interested in this 1920 magazine which has a detailed
> description of the Alexanderson System for Radio Communications, amongst
> other things.
>
>
http://cgi.ebay.com.au/General-Elecrtic-Review-Magazine-1920_W0QQitemZ1704203778\
77QQcmdZViewItemQQptZAU_Electronics_Vintage_Electronics?hash=item27add89915
>
> Bob
>
>
> [Non-text portions of this message have been removed]
>

Hi Walter,

You wrote:

> Germany doesn't expect its enemies around Christmas ....

I'm a brave taxpayer, therefore I have a right to be paranoid, eh?

> Your Idea with the Conrad amp is good. I'll order a few and
> see how they behave.

"danieletincani"'s (hi!) proposition is much better of course.
It should be easy to modify the circuit board from "Conrad" according to that.

> Frohe Weihnachten und einen guten Rutsch,

Thank you Walter, ebenfalls alles Gute fuer 2010, etc.!

Peter, 54N 10E

PS: wanna see another horror scenario?
http://www.df3lp.de/fh/wfs/wf_09-12-18.png
Location: Kiel City, 3rd floor, balcony

Hello Bob and VLF group
I put pdf's of some of the Alexanderson patents in the files section some
year(s) ago, found there, if it is not removed by webmaster due to lack of
space.
Very interesting reading. 
Best regards
Trond J.Hvaler archipelago, SE Norway59.0333N 11.0333E JO59MA


--- On Sat, 19/12/09, Bob <bob.vk7zl@...> wrote:

From: Bob <bob.vk7zl@...>
Subject: [VLF_Group] Alexanderson System
To: VLF_Group@yahoogroups.com
Date: Saturday, 19 December, 2009, 0:26
















 









       Greetings all

An enthusiast may be interested in this 1920 magazine which has a detailed

description of the Alexanderson System for Radio Communications, amongst

other things.



http://cgi.ebay. com.au/General- Elecrtic- Review-Magazine- 1920_W0QQitemZ17
0420377877QQcmdZ ViewItemQQptZAU_ Electronics_ Vintage_Electron ics?hash=
item27add89915



Bob



[Non-text portions of this message have been removed]






























[Non-text portions of this message have been removed]

Greetings all
An enthusiast may be interested in this 1920 magazine which has a detailed
description of the Alexanderson System for Radio Communications, amongst
other things.

http://cgi.ebay.com.au/General-Elecrtic-Review-Magazine-1920_W0QQitemZ1704203778\
77QQcmdZViewItemQQptZAU_Electronics_Vintage_Electronics?hash=item27add89915

Bob


[Non-text portions of this message have been removed]

Walter wrote:
>
> filter before amplification would violate the lo input impedance.
> You can't have a passive LC filter with zero wave impedance.

One must regard these numbers in the right perspective, Walter.
You can*t have a receiving loop or an amplifier input with zero
impedance either. The significant question is how much the overall
performance is improved with the right compromise. Do you prefer a
low impedance or high impedance design?

> And fetching the energy out of the air? Nice idea.

Don't expect wonders. You can attenuate the interference to some
degree, but not eliminate it. The larger the 'shielding' area, the
more expensive this solution will be and the more will the desired
signal be degraded as well. Shielding the source very locally is
the most effective approach in this regard.

Regards, Peter S.

Hi Walter,

I'm happy with this one by Renato Romero and Marco Bruno:
http://www.vlf.it/easyloop/_easyloop.htm

I replaced the OP27 with a LT1028 which has better overall performances and
changed values in the 27Kohm/330pF filter to extend the bandwidth up to 48KHz. I
use my magloop on the balcony and have no big problems (in my opinion) above
10KHz.
Under 5KHz I have noise from all sort of domestic and industrial devices around
me (I live in a suburban area). The lower the frequency, the stronger the noise
level. If you like, I can send to you a screenshot showing the actual spectrum I
see normally.

Best regards
Daniele

--- In VLF_Group@yahoogroups.com, "Peter, 54N 10E" <df3lp@...> wrote:
>
> Hi Walter,
>
> May be that mic-preamp from Conrad could help:
> http://www.df3lp.de/misc/preamp/preamp-Conrad_mod.jpg
> Artikel-Nr.: 197688-LN, 8.16 Eur., built in 20 min.
>
> Throw away the LF351, use NE5534 or OP27 instead. I replaced some resistors by
metal-film ones for lower noise, but never checked the increase in performance.
>
> Peter, 54N 10E
>
> PS: DHO, 23.4, off air since 11:00utc.
> Same procedure as last year?
> If "yes": bye until 2010!
>
> You wrote:
> > ...
> > Any approved circuit diagrams around here for a loop preamp with high
> > linearity? Want to bootstrap the interesting signals away from the noise
level but not have cross mod from the tv. Thereafter I can use
> > a LP filter to suppress the tv signal.
> > ...
>

Hi group,

I reported a couple of times about a (local?) source with spectral
lines roughly 5 kHz apart.
Today I used a emu 0202 to watch the signal up to 96 kc. At times this strange
signal extends up to the upper limit of the sound card.
I have the 17th line at 83 kHz, so the base band is 83/17 = 4.882 kHz.
A detailed look reveals side bands at 100 Hz spacing.
Somebody here who knows comm standards and can identify this frequency?
I tried powering down my ISDN and the DSL modem without success.
But i did not cut the cable at the entry point into the house ....
What about PLC ?

Merry Christmas and a Prosperous +) New Year,

Walter

+) spelling? - live long and knusper!

Hi Peter,

Germany doesn't expect its enemies around Christmas ....

Your Idea with the Conrad amp is good. I'll order a few and
see how they behave.

Frohe Weihnachten und einen guten Rutsch,

Walter

Hi Walter,

May be that mic-preamp from Conrad could help:
http://www.df3lp.de/misc/preamp/preamp-Conrad_mod.jpg
Artikel-Nr.: 197688-LN, 8.16 Eur., built in 20 min.

Throw away the LF351, use NE5534 or OP27 instead. I replaced some resistors by
metal-film ones for lower noise, but never checked the increase in performance.

Peter, 54N 10E

PS: DHO, 23.4, off air since 11:00utc.
Same procedure as last year?
If "yes": bye until 2010!

You wrote:
> ...
> Any approved circuit diagrams around here for a loop preamp with high
> linearity? Want to bootstrap the interesting signals away from the noise level
but not have cross mod from the tv. Thereafter I can use
> a LP filter to suppress the tv signal.
> ...

Hi Shawn,
     Hope you are doing OK.
     I had put a couple of postings on the VLF reflector asking if
anybody notices any change in Tweek characteristics when there is
Sporadic E present (usually in the Summer months). Nobody has  commented
at all. I know you listen a lot so I wondered if you have ever noticed
any variation in amplitudes and tail lengths (damping)?


Percy.


[Non-text portions of this message have been removed]

Thanks for responses,

filter before amplification would violate the lo input impedance.
You can't have a passive LC filter with zero wave impedance.
Not even with Bears microwave oven transformers :-)
Beside the fact that I don't like to replace a relatively new TV  a LCD would
create other problems. I can look at the broadband noise from my computer
monitor.
And fetching the energy out of the air? Nice idea. The loop is 1.2 m square and
located in the first floor. The tv is on the ground floor almost exactly below.
I know this is a bad situation. But no other place available. And I don't want
to drive into the meadows for every single test.
But would be a nice simulation task to find out how large such a sucking loop
needs to be and where to place it. Any ideas how to do it?

Walter

and no I don't have the money for 25 square meters of metglass ....

You won't have that problem when you upgrade to an LCD, Plasma, etc.

Jim

--- In VLF_Group@yahoogroups.com, "Walter" <fedderwi@...> wrote:
>
> Hi group,
>
> still fiddling with the air core loop located on the balkony.
> Found out that I have a huge signal from the tv set downstairs.
> Now this is a receiver in "100 Hz Technik" meaning the mag field of the
> line frequency is at 31.25 kHz outside of the band of interest.
> But it creates cross modulation.
>
> Any approved circuit diagrams around here for a loop preamp with high
> linearity? Want to bootstrap the interesting signals away from the noise level
but not have cross mod from the tv. Thereafter I can use
> a LP filter to suppress the tv signal.
>
> Basically I tried the first stage from Peters (Kiel) design. This
> is a simple transistor amp. Best suited for a mobile app and battery supply.
>
> Walter
>
> ps : a pig where you can have wool eggs and milk as well
>

Walter wrote:
> still fiddling with the air core loop located on the balkony.
> Found out that I have a huge signal from the tv set downstairs.
> Now this is a receiver in "100 Hz Technik" meaning the mag field of
> the line frequency is at 31.25 kHz outside of the band of interest.
> But it creates cross modulation.
>
> Any approved circuit diagrams around here for a loop preamp with high
> linearity? Want to bootstrap the interesting signals away from the
> noise level but not have cross mod from the tv. Thereafter I can use
> a LP filter to suppress the tv signal.

I would rather recommend to attenuate the interfering signal
component prior to amplification, not afterwards. Otherwise you
would need an amplifier with elevated power supply requirements
(not desired for battery operation) and operated at low gain,
which comes with a noise performance less than optimal.

With a high impedance amplifier input, I have always made the
receiving loop part of an L-C low pass filter and added an
additional load resistor to eliminate the resonance peak.
This makes a 2nd order low-pass filter prior to the amplifier.

With a low impedance amplifier input, the sensing loop would
exhibit a 1st order low-pass response already by itself, thus
attenuating the TV line frequency in comparison to the band of
interest.

With a low impedance amplifier input, you can also use a resonance
tank (with L and C connected in parallel) in series with the signal
line between the loop and the amplifier input, thus forming a notch
at the TV line frequency. The inductor of that notch tank should
utilize a (toroidal) ferrite core with the magnetic path completely
closed within the core.

Regards, Peter S.

Walter wrote:
> Hi group,
>
> still fiddling with the air core loop located on the
> balkony. Found out that I have a huge signal from the tv
> set downstairs. Now this is a receiver in "100 Hz
> Technik" meaning the mag field of the line frequency is
> at 31.25 kHz outside of the band of interest. But it
> creates cross modulation.

Just a thought.  What about a low pass filter in the space
between the TV and the antenna?  A shorted loop of high
conductivity around the path between the source and the
antenna may be able to reduce the strength of the
interference without altering the antenna or the preamp.

If the TV is yours, you might experiment with placing the
loop close to the TV (around the case or on the ceiling/wall
above it), so that it surrounds the path between TV and
antenna.  The closer you can get the shorted loop to the
picture tube yoke, the smaller it can be for the same
attenuation.  You might be able to place it inside the TV case.

--
Regards,

John Popelish

Hi group,

still fiddling with the air core loop located on the balkony.
Found out that I have a huge signal from the tv set downstairs.
Now this is a receiver in "100 Hz Technik" meaning the mag field of the
line frequency is at 31.25 kHz outside of the band of interest.
But it creates cross modulation.

Any approved circuit diagrams around here for a loop preamp with high
linearity? Want to bootstrap the interesting signals away from the noise level
but not have cross mod from the tv. Thereafter I can use
a LP filter to suppress the tv signal.

Basically I tried the first stage from Peters (Kiel) design. This
is a simple transistor amp. Best suited for a mobile app and battery supply.

Walter

ps : a pig where you can have wool eggs and milk as well

I wouldn't bet on it unless NOAA agrees, Spaceweather has a record of seeing and
predicting CMEs that dont seem to come our way.

Alan G3NYK


--- On Thu, 17/12/09, kg4inu <w4gon@...> wrote:

> From: kg4inu <w4gon@...>
> Subject: [VLF_Group] INCOMING CME
> To: VLF_Group@yahoogroups.com
> Date: Thursday, 17 December, 2009, 0:34
> Finally some activity!
>
>
http://spaceweather.com/images2009/16dec09/stereoa_cor2_cme.gif?PHPSESSID=rclefm\
3s6m15c131alovu48hv3
>
> Joel
>
>
>
> ------------------------------------
>
> Post message: VLF_Group@yahoogroups.com
>
> Subscribe:  VLF_Group-subscribe@yahoogroups.com
>
>
> Members may request the option of receiving just one e-mail
> per day which contains all of the days comments. Simply send
> an e-mail to the list owner (VLF_Group-owner@yahoogroups.com)
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>
>
>     VLF_Group-fullfeatured@yahoogroups.com
>
>
>

Finally some activity!

http://spaceweather.com/images2009/16dec09/stereoa_cor2_cme.gif?PHPSESSID=rclefm\
3s6m15c131alovu48hv3

Joel

Hi Wolf, finally I managed to work around the issue.

It seems that the "wrong" setting was to configure an input sampling frequency
of 96KHz. With 48KHz all works as expected. This value cuts max frequency of my
monitoring to 24KHz of course, but this is not really a big limitation for my
purposes.

Probably there is some sort of conflict with the actual characteristics of the
audio controller on my PC, despite of the fact that windows allows me to
configure 96KHz as the sampling rate on line input.

Best regards
Daniele

--- In VLF_Group@yahoogroups.com, "danieletincani" <danieletincani@...> wrote:
>
> Hi Wolf, thank you very much for your reply.
> Basically I'm interested in narrow-band listening like RTTY, CW, etc..
Unfortunately my free time is too tight and my environment is by far too noisy
for natural radio monitoring.
>
> Best regards
> Daniele
>
> --- In VLF_Group@yahoogroups.com, "dl4yhf" <dl4yhf@> wrote:
> >
> > Hi Daniel,
> >
> > I will send details in a personal message, as soon as time permits.
> > The best configuration depends on what you actually want to do; broadband
listening (as for VLF natural radio), or narrow-band filtered audio (to hunt for
'utility' signals on VLF).
> > The colour palette ist just a matter of taste. More important is to adjust
the waterfall's "contrast" and "brightness" controls to get the best results,
which also depends on the dynamic of the signal you want to observe.
> >
> > Cheers,
> >   Wolf DL4YHF .
> >
> > --- In VLF_Group@yahoogroups.com, "danieletincani" <danieletincani@> wrote:
> > >
> > > Hi all,
> > >
> > > may I ask you some simple question about SpecLab? Basically I'm using it
(with a 40-turns loop and a low-noise pre-amplifier) for "looking" at VLF
signals in the 10KHz-48KHz range of frequencies. My questions are:
> > > 1) which settings (from the list of SpecLab ready-to-use configurations)
would you advise as the best fitting for my purposes?
> > > 2) currently I'm using the "SAQrcvr1" settings but I'm not satisfied with
the quality of video output. Which palette would you choose to enhance the
"contrast" between good signals and the noise floor?
> > > 3) when I try to log the input stream to a .WAV file it works pretty good.
On the contrary, when I try to log the output stream (out of a bandpass filter),
the .WAV file I get contains only an intermittent noise in place of the sound I
was hearing during monitoring. Which setting am I missing?
> > >
> > > Thank you all in advance for any help.
> > > Regards
> > > Daniele
> > >
> >
>

> Ebino Japan is at 22.2Khz. and LeBlanc, France is at 18.3Khz. Both are much
stronger in the early mornings as in a few hours ago.

Thanks, they both seem to still be coming through here at 1700UTC.

Joel

Ebino Japan is at 22.2Khz. and LeBlanc, France is at 18.3Khz. Both are much
stronger in the early mornings as in a few hours ago.

http://electricterra.com/Data/VLFBeacon/0912161100.jpg

--- In VLF_Group@yahoogroups.com, "kg4inu" <w4gon@...> wrote:
>
> > Conditions have been pretty decent lately Joel.
> > http://electricterra.com/Data/VLFBeacon/0912160500.jpg
>
> Indeed. If possible can you tell me where (frequencies) the DX stations are
located in your plot? I always have a hard time IDing these TXers. :)
>
> Joel
>

> Conditions have been pretty decent lately Joel.
> http://electricterra.com/Data/VLFBeacon/0912160500.jpg

Indeed. If possible can you tell me where (frequencies) the DX stations are
located in your plot? I always have a hard time IDing these TXers. :)

Joel