RF transformer

Probably a careless reprint of a circuit from the Navy's electronic manual (I don't remember the website, but it turns up often on these subjects). They, of course, used *electron current flow*, just to be different.

Often, the diodes in those old schematics (when electron and conventional current were still open for debate) would specify with a + and -. So you'd see a diode drawn anode-to-cathode with a plus and minus respectively (i.e., the rectifier makes the minus side negative, because the symbol is pointing *electrons* in that direction).

Don't forget those old circuits with germanium PNP BJTs, with a negative supply on the top and backwards-pointing emitters on bottom. :)

Tim

On a sunny day (Mon, 29 Jul 2013 11:05:14 -0800) it happened Robert Baer wrote in :

I had good AM rejection in the TV demod 5.5 MHz, 8 mm diameter formers, at 1 cm spacing those almost touch. You propbably want a good limiting amplifier. But please tell us: Is it narrow band FM (at 1 MHz????) It should be... other methods may be better (PLL, quadrature).

I had some nice formulas for calulating bandfilters, no idea where that is.

LC coupling LC and LC -C- LC etc Once had to do a whole lot a 19 inch rack full ...

On a sunny day (Mon, 29 Jul 2013 11:22:47 -0800) it happened Robert Baer wrote in :

You have to start somehere...

On a sunny day (Mon, 29 Jul 2013 23:00:07 -0700) it happened Jeff Liebermann wrote in :

Yes, and one old way to demodulate FM with a AM radio was 'slope detection',

So, basically OP can use any MW radio for 1 MHz.. ;-)

This gives some other detectors, like 'ratio detector' that I like personally:

What's wrong with their current name? "Screwed Taxpayers, Inc."

I have one on genuine dead tree slices. It has a Bohr atom, boats, and a nicely drawn tube on the front. It also has a TO-3-ish transistor hastily drawn in above the tube. The cover says it is NAVPERS 10087-C and the inside front page gives a Stock Ordering No. of 0500-031-0110.

Most of these schematics don't have the + and - on the diodes, but Chapter 3 has a diode symbol with a separate "forward current" arrow pointing against the diode.

The ratio detectors are in chapter 26. Figure 26-16 shows that the "bottom" plate of the cap on the far right is positive, backwards to what the above link shows. That same figure also has little arrows drawn on it (in the original) to show the charging path for that cap, and they run opposite to the way the diodes point.

Figure 26-18 sort of matches the above link, but the cap on the far right isn't specifically called out as electrolytic - it just has the flat plate on top and curved plate on the bottom, no plus sign by one plate.

For some reason, the Navy liked to have a capacitor from the top end of the primary winding to the middle of the secondary winding.

The appendices tell me that I need an AN/ABC-1 (or possibly an AN/DBC-1, depending on the definition of "pilot") to implement RFC 1149.

Matt Roberds

On a sunny day (Tue, 30 Jul 2013 21:54:15 -0800) it happened Robert Baer wrote in :

Na...

So far so good, I did a narrow band FM receiver with an IF of 455 (LC + Murata ceramic filters), and a Motorola chip (would have to climb the attic for teh type number, still have one with filters), Superhet. The Motorola chip has a quadrature detector, noise detector (out of band audio) for squelch.

Lost you here, we were talking FM no?

??? Explain plz.

Do not worry, the wavelength was even bigger than you can imagine in my 19 inch 'case' (crate?) LOL

On a sunny day (Wed, 31 Jul 2013 05:03:25 GMT) it happened Jan Panteltje wrote in :

Correction, actually that was a MECHANICAl filter IIRC!

Find my confession to crazyness. IF frequency: 455KC, bandwidth: standard AM of 10KC max; trial use on SSB signals. Moused up version of FM detector to enhance AM detection and suppress "duck talk" SSB - which is backwards and upside-down use of standard FM detector. Nineteen inch rack does not match wavelength..

You have ordered a disappointment - SSB comes out as Donald Duck even from a FM detector.

For the 455 kHz IF bandwidths, FM must be narrow-band (not much energy outside the first pair of sidebands). IIRC, a hard-limiting IF strip and a discriminator is the way to go, instead of a ratio detector.

• So not as quacked-up as i thought..

• That is good for FM, not AM; better would be the equivalent to an un-limiter..

IIRC, you were asking for a discriminator transformer.

Enhanced AM detection goes by creating a in-phase local copy of the AM carrier and using a product detector with it. Here SSB comes out well, if you can create a copy of the non-existing carrier.

First cut is to use and work with an FM discriminator for AM and SSB.

On a sunny day (Thu, 01 Aug 2013 14:02:01 -0800) it happened Robert Baer wrote in :

Hope that helps.

Recently, after years of testing, researchers have found that mice have four feet, to within 10 sigma.

Debate continues if the tail should be counted as a fifth. This would cause a frequency modulation of the amount of feet whenever tail hits ground, destroying the confidence in the 10 sigma result. More funding is required to make more precise measurements to see if this finding makes changes in the standard mouse model necessary.

Does this include computer mice?