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the rest of the Bonadio article on 'EAM' ?




 
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Author Topic: the rest of the Bonadio article on 'EAM' ?  (Read 2702 times)
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Patrick J. / KD5OEI
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« on: December 30, 2013, 09:04:48 PM »

here is page 1:
http://www.amwindow.org/tech/pdf/eam.pdf

Page 1 is all over. Has anyone page 2 or the rest of the article?

I guess it's just about pre-emphasis, but I'd still like to read the rest of it.
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« Reply #1 on: January 03, 2014, 12:19:28 PM »

That article is from The AM Press Exchange. Most of the issues are archived on this site.

http://amfone.net/AMPX/ampx.htm
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« Reply #2 on: January 03, 2014, 01:36:58 PM »

Aye, it seems many are not, according to the article indexes. Unless I'm doing it wrong.

In any case I had no idea Mr. Bonadio wrote things like many-part article on why AM is superior to SSB, and on tapping atmospheric charge, an interesting energy harvesting topic, and today certainly possible since small yet communicative things, designed for the purpose, require microampere average current - remote sensors come to mind. Indeed, I worked with this application among many at my former employer. I shall miss it, making 'whatever the customer wanted to do' a reality. Satisfying.

It would be worth a few bucks to have all the Press Exchange on CDROM. Or just have them all on line. Are the missing ones really lost? Maybe some day.
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« Reply #3 on: January 03, 2014, 01:46:10 PM »

Several guys made quite an effort to get those issues on line. I don't know if that's all the hard copies they have or the energy for the project died out over time. I would be nice to have them all on line.
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« Reply #4 on: January 04, 2014, 02:51:28 PM »


I wonder if George is still a going concern?

He has some interesting stuff around the net. Here is one:

http://www.freepatentsonline.com/4182754.pdf

There was also some WW2 stories, and how he cured malaria. I cannot find them, but there is some good stuff on how he helped out with the build up to D-Day..He sure is an interesting feller...

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« Reply #5 on: January 04, 2014, 08:57:11 PM »

He was still alive as of a few years ago. Have heard anything lately.
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« Reply #6 on: January 04, 2014, 09:19:57 PM »

IIRC, he was in charge of inventory, for lack of a better term, of the gear sent over on D-Day; trucks, half tracks, DD tanks, etc etc. He has a good write up on one of the military sites. I may have posted it here some years ago.

Yes Pat, it's about pre-emphasis, but it's worth seeking out the rest of the article as well as others he wrote (something about a 4 square aerial I think? and others). I talked with him quite a bit about those and other things in the late 80s/early 90s when I got active in AM, and he was quite interesting. He had a loud, peaky signal from W2WLR "Watertown's Little Radio" in NY. He actually offered me the old 32V he had used as the test bed for many of his articles for a parts source, but I never got over to pick it up.

He was into some kind of drops called Irrydium or similar that slowed the aging process. From the looks of his photos online, it must've worked as he never looked his age. Hopefully he's still with us.

I think I have most of the AM Press Exchange issues here somewhere in hardcopy, and the rest were online. The fellow who had been keeping them on his server passed away a few years back but I'm pretty sure he had passed them off before that. Might have that file saved as well, I'll look around.

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« Reply #7 on: January 04, 2014, 10:00:34 PM »

Bonadio "Space Dimension" B3D Antenna:

 http://www.hamelectronics.com/k1deu/pages/ham/antennas/pages/w2wlr/w2wlr_b3d.htm

Bonadio "Square Diagonal B2D Antenna:

page 1: http://www.hamelectronics.com/k1deu/pages/ham/antennas/pages/w2wlr/w2wlr_b2d_front.htm

Page 2 B2D: http://www.hamelectronics.com/k1deu/pages/ham/antennas/pages/w2wlr/w2wlr_b2d_back.htm

These notes courtesy John K1DEU.. RIP :
http://www.hamelectronics.com/k1deu/pages/ham/antennas/pages/w2wlr/index__w2wlr.htm
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« Reply #8 on: January 20, 2018, 08:56:13 AM »

I see that Mr. Bonadio passed away on July 12, 2015 at the age of 97. R. I. P.

Just continuing this interesting topic because I did some LTspice work on his LPF and also sourced a selection of inexpensive inductors for it. I did deviate a few percent from his given values but the deviation seems to have had little effect aside from only slightly increasing the cutoff frequency. Bonadio's inductors are 30.6mH and 20.27mH. These values are uncommon, but could be made up by series connection the smaller values to trim the inductance up if one wants to make the exact design. I made an effort to use standard 10mH values because 20mH and 30mH coils are not common, so one would use two for the 20mH coil and three for the 30mH coil.

The most important thing I learned is that the inductors must have quite low DC resistance, or two things happen. One is the sharp notches in the response diminish with the curve becoming smoother and less aggressive, and the other is that the frequencies just before cutoff suffer, the knee being softer.

Inductors are costly, but if one can stomach $4 each, for five inductors of 2.3 Ohms each, the result is very good. If one will spend $15 on each for 1.55 Ohm inductors, it is as close as anything can be. 99-cent inductors of 7.3 Ohms are usable, but the deviations mentioned in the above paragraph are much more pronounced.

The image us a comparison of these values in the circuit, with curves, inductor part numbers, and vendors stocking them. Hope that might be helpful for those who like a simple analog LPF.

I don't push filters on anyone, but it may be useful if one uses pre-emphasis, which is another thing Mr. Bonadio advocated. The filter would go at the line level input to the speech amp. Of course it is useless of the speech amp and modulator are not clean and add their own noise above the desired cutoff frequency.

-0dB@3.33KHz
-3dB@3.48KHz
-6dB@3.54KHz
-12dB@3.63KHz
-47dB@4.00KHz


* LPF with part numbers.png (87.08 KB, 1247x881 - viewed 45 times.)
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« Reply #9 on: January 20, 2018, 09:29:15 AM »

These two circuits give a pre-emphasis, followed by the LPF filter In these, the LPF filter was simulated with the standardized component values for the inductors, 20mH and 30mH, which can be made of 10mH parts.

Please note that the RC network pre-emphasis hookup giving +5dB at 3.3KHz is very lossy, about 35dB, as opposed to the LPF which is not lossy in its passband. The two section pre-emphasis network giving +10dB at 3.3KHz is much lossier.

Above each voltage source in a diagram is a text statement such as "AC562" This means that to get 1V out from the network, 562V peak is required to input from the source. Obviously it isn't practical to have to put that that much voltage into 500 Ohms and some op-amp based pre-emphasis circuit would be better. The other circuit, with just 5dB of treble boost, still needs 50V input. I think that R30 might be able to be removed without harm. The three 750 Ohm resistors give 500 Ohms in and out between the pre-emphasis and the LPF.

These two are not so practical but they let me see possible response curves and play with the values. The TXT file is actually a LTspice .ASC file, so others can play around with this if they want. Just rename to .ASC


* pre-emph 5dB plus LPF.png (54.87 KB, 1055x1009 - viewed 38 times.)

* pre-emph 10dB plus LPF.png (50.82 KB, 1055x1009 - viewed 42 times.)
* bonadio speech filter with part numbers.txt (8.05 KB - downloaded 24 times.)
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