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RF transformer

Started by Robert Baer July 29, 2013
On a sunny day (Mon, 29 Jul 2013 08:52:54 -0700) it happened Jeff Liebermann
<jeffl@cruzio.com> wrote in <r83dv8998jdi0a65st1hdqdpahc8qu0ifb@4ax.com>:

>On Mon, 29 Jul 2013 15:23:20 GMT, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >>Hey I just had a discussion at CNN.com. and found out how to get rid of the US deficit: >>Advertising on dollar bills, on banknotes, > >That's already being done, sorta: ><http://www.tosscards.com/million.htm> >About $0.05/ea. One of the local Pizza houses was passing them out >recently.
That is nice :-)
>However, it might be possible to do what the various baseball and >football stadiums have done for many years. Like renaming the stadium >after major sponsors, we should rename government buildings, programs, >and monuments after corporate sponsors. Instead of the white house, >it should be the Verizon house, or something equally disgusting. >Instead of naming airports and freeways after famous politicians, they >should be named after corporate sponsors. For example, the Starbucks >freeway.
Yes, that would help, but perhaps the politcians egos would not like that... I also suggested replacing George Washington on the banknotes with beautiful naked women.
On 07/29/2013 08:52 AM, Jeff Liebermann wrote:
> On Mon, 29 Jul 2013 15:23:20 GMT, Jan Panteltje > <pNaonStpealmtje@yahoo.com> wrote: > >> Hey I just had a discussion at CNN.com. and found out how to get rid of the US deficit: >> Advertising on dollar bills, on banknotes, > > That's already being done, sorta: > <http://www.tosscards.com/million.htm> > About $0.05/ea. One of the local Pizza houses was passing them out > recently. > > However, it might be possible to do what the various baseball and > football stadiums have done for many years. Like renaming the stadium > after major sponsors, we should rename government buildings, programs, > and monuments after corporate sponsors. Instead of the white house, > it should be the Verizon house, or something equally disgusting. > Instead of naming airports and freeways after famous politicians, they > should be named after corporate sponsors. For example, the Starbucks > freeway. >
"The United States of Walmart" has sort of a ring to it...
On 29/07/13 08.54, Jeff Liebermann wrote:
> On Sun, 28 Jul 2013 21:48:14 -0800, Robert Baer > <robertbaer@localnet.com> wrote: > >> I understand, that with the proper winding configuration, that a 90 >> degree phase shift can be achieved between primary and resonant secondary. >> That is done with a tapped secondary on a FM discriminator transformer. > > That would be a Foster Seeley Discriminator, except there is no 90 > phase shift involved: > <http://www.tpub.com/neets/book12/51c.htm> > A 90 degree phase shift demodulator would be a quadrature demodulator.
... Hi Jeff & Robert I hope I some day will design a Foster Seeley Discriminator or better yet a Ratio detector. The Ratio detector because it has built-in limiter functionality. - According to this site there is a 90 degree shift needed: http://www.radio-electronics.com/info/rf-technology-design/fm-reception/foster-seeley-fm-detector-discriminator.php Quote: "... To obtain the different phased signals a connection is made to the primary side of the transformer using a capacitor, and this is taken to the centre tap of the transformer. This gives a signal that is 90 degrees out of phase. ..." - By chance I found a schematic some months ago, with a Ratio Discriminator with AFC functionality. I did not imagine that it could, because I read some decades ago that only a Foster Seeley was associated with AFC functionality. Here is the schematic with the Ratio Discriminator with AFC functionality: http://www.radiohistoriskforeningvest.dk/Diagrammer/Blaupunkt-Derby%20de%20Luxe-7659700-1968-diagram.png Main: http://www.radiohistoriskforeningvest.dk/Diagrammer/Diagramsiden.php (look for: Blaupunkt-Derby de Luxe-7659700-1968-diagram.png ) AFC goes through R931 (top-right) to left to R784 (AFC limited by V40C2 two diodes) through R782, R755 (top mid) and finally to BA124 - used as varactor. Ratio Discriminator: http://www.radio-electronics.com/info/rf-technology-design/fm-reception/ratio-fm-detector-discriminator.php Quote: "... When circuits employing discrete components were more widely used, the Ratio and Foster-Seeley detectors were widely used. Of these the ratio detector was the most popular as it offers a better level of amplitude modulation rejection of amplitude modulation. This enables it to provide a greater level of noise immunity as most noise is amplitude noise, and it also enables the circuit to operate satisfactorily with lower levels of limiting in the preceding IF stages of the receiver. ..." /Glenn
On a sunny day (Mon, 29 Jul 2013 08:45:27 -0700) it happened RobertMacy
<robert.a.macy@gmail.com> wrote in <op.w0zp12su2cx0wh@ajm>:

>> Hey I just had a discussion at CNN.com. and found out how to get rid of >> the US deficit: >> Advertising on dollar bills, on banknotes, >> how much does google make ... FED can do it too. >> Made available to all for free. >> (And in that discussion I invented gambling on banknotes too). >> So there you are, I like LTspice, in runs in wine (that is a windows >> emulator for the microsof users), >> so I can actually use it. >> It is the best I have seen (LTspice, not wine). > >Great ideas!! If Facebook can turn a profit of $480M in this economy then >the govt should be able to do the same thing! > >Uh, who paid that $480M? and, did THEY make a profit? Who's spending this >money?
Yes that is always that question, there is the issue of market share too, no advertising and people will forget you exist... As to the math and circuit thing,. I see it very much this way: A baseball player will throw or catch a ball, neural net.. A mathematician will need to know every freaking detail, altitude, speed, air pressure, size, material, wind direction, etc etc... and then spend the next few hours calculating, and the ball, well the ball will be lost. There were a few students some time ago who build a ball catching machine, I think it was on youtube, really cool, but very controlled setup of course. But, having programmed some neural nets, neural nets can give really bad answers too... It is a matter of training, and topology, a research area really. The way we teach the next generation is for a large part by spoon feeding them the equations. without them having that 'hand on' experience that the baseball player has so to speak. A parrot is not a good designer. Luckily there are genetic variations and ever so often somebody is born and left intact enough to get humanity a bit further.. Test boards I make usually simply work (apart from wiring errors), and I made many in the past and took almost as many apart again, just fun to get something working, deepening understanding (as weights in the neural net, not always - or usually not, as mathematical models). There is software too, in one way it is mathematically 100% exact, so a bit of both. I am not against math or something, just see it as a sub-circuit, a SMALL sub-circuit, in the human neural net. The 100 turns I came up with with w^2.L.C blah blah is justification, the 100 comes from the neural net. I have wound so many coils in my life I definitely did a 1 MHz one once... Was that not one of the first, a MW crystal radio? shift in ferrite rod for tuning.
On 29.7.13 7:22 , Glenn wrote:
> On 29/07/13 08.54, Jeff Liebermann wrote: >> On Sun, 28 Jul 2013 21:48:14 -0800, Robert Baer >> <robertbaer@localnet.com> wrote: >> >>> I understand, that with the proper winding configuration, that a 90 >>> degree phase shift can be achieved between primary and resonant >>> secondary. >>> That is done with a tapped secondary on a FM discriminator >>> transformer. >> >> That would be a Foster Seeley Discriminator, except there is no 90 >> phase shift involved: >> <http://www.tpub.com/neets/book12/51c.htm> >> A 90 degree phase shift demodulator would be a quadrature demodulator. > ... > > Hi Jeff & Robert > > I hope I some day will design a Foster Seeley Discriminator or better > yet a Ratio detector. The Ratio detector because it has built-in limiter > functionality. > > - > > According to this site there is a 90 degree shift needed: > http://www.radio-electronics.com/info/rf-technology-design/fm-reception/foster-seeley-fm-detector-discriminator.php > > Quote: "... > To obtain the different phased signals a connection is made to the > primary side of the transformer using a capacitor, and this is taken to > the centre tap of the transformer. This gives a signal that is 90 > degrees out of phase. > ..." > > - > > By chance I found a schematic some months ago, with a Ratio > Discriminator with AFC functionality. I did not imagine that it could, > because I read some decades ago that only a Foster Seeley was associated > with AFC functionality. > > Here is the schematic with the Ratio Discriminator with AFC functionality: > http://www.radiohistoriskforeningvest.dk/Diagrammer/Blaupunkt-Derby%20de%20Luxe-7659700-1968-diagram.png > > Main: > http://www.radiohistoriskforeningvest.dk/Diagrammer/Diagramsiden.php > (look for: Blaupunkt-Derby de Luxe-7659700-1968-diagram.png ) > > AFC goes through R931 (top-right) to left to R784 (AFC limited by V40C2 > two diodes) through R782, R755 (top mid) and finally to BA124 - used as > varactor. > > > Ratio Discriminator: > http://www.radio-electronics.com/info/rf-technology-design/fm-reception/ratio-fm-detector-discriminator.php > > Quote: "... > When circuits employing discrete components were more widely used, the > Ratio and Foster-Seeley detectors were widely used. Of these the ratio > detector was the most popular as it offers a better level of amplitude > modulation rejection of amplitude modulation. This enables it to provide > a greater level of noise immunity as most noise is amplitude noise, and > it also enables the circuit to operate satisfactorily with lower levels > of limiting in the preceding IF stages of the receiver. > ..." > > /Glenn >
The circuit (while quite correct) in not too carefully drawn: the signal from the diodes charges the electrolytic capacitor in reverse polarity. -- -T.
On Mon, 29 Jul 2013 07:53:29 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sun, 28 Jul 2013 23:54:03 -0700, Jeff Liebermann <jeffl@cruzio.com> >wrote: > >There's a detailed explanation of how to design an FM discriminator >for AFC in the Radiotron Designers Handbook 4th edition (1953) Pg >1152-1156. ><http://www.paleoelectronics.com/RDH4/CHAPTR29.PDF> >Note the concern for controlling the Q of both the primary and >secondary.
Yup. The Big Red Book ;-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Tim Williams wrote:
> "Robert Baer"<robertbaer@localnet.com> wrote in message > news:jumJt.296288$aW2.143211@fx13.iad... >> I understand, that with the proper winding configuration, that a 90 >> degree phase shift can be achieved between primary and resonant >> secondary. >> That is done with a tapped secondary on a FM discriminator >> transformer. >> What are the guidelines and requirements needed to construct such a >> transformer at a given frequency OTHER than the standard 10.7Mhz? >> Say, on a form in the one inch diameter region, and frequency below >> 1Mhz? > > You need LL high enough (k low enough) that the resonant tank, at whatever > Q it ends up at, doesn't draw an excessive amount of current (excessively > double-humping that stage's IF response), without being so high that the > signal is too small. Just basic IF transformer and bandpass filter stuff. > >> Ideal coil diameter, length based on chosen frequency? > > Well, you generally get best results with a coil 0.5 to 2" long, pitch > twice the wire diameter. Assuming that the form is 1" as stated. That's > true of coils in general; were you expecting something specific to this > application?
* OK, i confess my madness here. 455KC FM discriminator transformer, reasonably optimized for linear operation and max AM rejection. That is my initial target (for further madness).
> >> Turns / inductance > > Depends on circuit impedance, but easily figured from the nature of the > network. > >> (no resonating cap)? > > As in, self resonant?
* No; what should the target inductance be (of the coil without a resonating cap) WRT frequency? That way i could calculate the needed resonating cap.
> > At<1MHz? You're going to need more than 1" diameter to get a resonator > down there. Especially with any useful Q. > > Tim >
Jeff Liebermann wrote:
> On Sun, 28 Jul 2013 21:48:14 -0800, Robert Baer > <robertbaer@localnet.com> wrote: > >> I understand, that with the proper winding configuration, that a 90 >> degree phase shift can be achieved between primary and resonant secondary. >> That is done with a tapped secondary on a FM discriminator transformer. > > That would be a Foster Seeley Discriminator, except there is no 90 > phase shift involved: > <http://www.tpub.com/neets/book12/51c.htm>
* I disagree; look at the phase diagrams.
> A 90 degree phase shift demodulator would be a quadrature demodulator. > >> What are the guidelines and requirements needed to construct such a >> transformer at a given frequency OTHER than the standard 10.7Mhz? > > Make sure the xformer bandwidth (or Q) is sufficiently low that it > covers the range of frequency deviation you're expecting. Too wide a > range, and you get low detected output voltages. Too high a Q or too > narrow a range, and the discriminator can't handle the maximum FM/PM > deviation. Note that both the primary and secondary of the > discriminator xformer are tuned. > >> Say, on a form in the one inch diameter region, and frequency below 1Mhz? >> Ideal coil diameter, length based on chosen frequency? >> Turns / inductance (no resonating cap)? > > Fill in the blanks: > 1. Center frequency. > 2. Maximum deviation or modulation acceptance bandwidth. > 3. Maximum modulation frequency (or modulation index). > 4. Linearity required (optional). > 5. Do you need AM rejection? Discriminator is also sensitive to AM. > 6. What do you have against tuning capacitors? > > There are too many other specs that have to nailed down (size, tuning > range, stability, footprint, solderability, etc) in order to design a > proper discriminator coil. I don't want to do that. > >
RobertMacy wrote:
> > use free femm 4.2 to design coil > > use LTspice to design 'circuit' based upon parameters determined from femm. > > BOTH user groups, super helpful
Thanks. Now digging into my old,dusty RCA Radiotron.
Jan Panteltje wrote:
> It is actually really simple: > Find a nice C value, 220 pF is my favorite. > Use online calculator to find L for resonance, or estimate from Xperience. > Use standard coil formers (8 mm diameter, or 6 mm diameter, whatever), > with adjustable cores. > Add some turns (how about 100? for 1MHz), > apply your F from source or generator. > Tune for maximum. > > Now make 2, put them, 1 cm next to each other,
* RCA Radiotron indicated tight coupling to achieve a double-humpped response for better linearty and AM rejection.
> wind 5 to 10 coupling turns from the first one, your LF comes from that. > do that diode thingy. > > I have done it twice, for TV audio (was 5.5 MHz FM here, > thing then needs to be very precise as else you get video rattle in the audio. > (the 5.5 MHz came from the video detector). > Did not take more than an hour to build and adjust.