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Author Topic: are class e rigs wide?  (Read 81574 times)
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kg8lb
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« Reply #100 on: November 12, 2009, 01:55:35 PM »

Quote
Check out these two local BC stations.
Which one is using the old plate modulated BTA?
Which is complying with the restricted modern standard?
Which sounds like crap?  Well, believe it or not, you actually have to listen to the audio.

This sounds like the old, "What's My Line" TV program.

I would guess the Country station is using plate modulation while the "local" station is using an IBOC mask.

Phil - AC0OB

  Wouldn't the actual program material make a difference as well ?  IE :Processed snare drums and cymbals VS a James Earl Jones voice over ...

  Apples to apples ?
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W1DAN
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« Reply #101 on: November 12, 2009, 02:07:39 PM »

Brett:

Any AM transmitter, regardless of type will splatter up and down the band in the same way if driven over 100% negative (and thus reach carrier cutoff). This creates complex products (spikes, square waves that also mix with themselves) that can be as wide as the tank circuit. The math is the same regardless of type.

AM modulation is the multiplication of the RF carrier by an audio signal.

For a mathematical discussion of good AM, look here:

http://en.wikipedia.org/wiki/User:WillWare/Radio_theory

It seems you are closing in on the idea of someone overmodulating as compared to cleanly modulating high frequency audio.

It'd probably be good to carefully look at strong AM broadcast stations (non IBOC) that are not overmodulating and compare this to someone obviously splattering on the CB band. Listening, tuning and looking at your spectrum display will reveal the clues over time.

As usual, you must be sure that your receiver and display are not creating their own artifacts. I have fooled myself doing this.

When you get a chance, let us know if it is overmodulation you suspect or just clean wide audio. By all means have a discussion with the operator.

Hope this helps!

73,
Dan
W1DAN
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steve_qix
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Bap!


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« Reply #102 on: November 12, 2009, 02:24:23 PM »

None of this has anything whatsoever to do with class E.

The EXACT SAME components are generated using a tube rig if it is operated under the same conditions.  The very same thing happens if there is overmodulation of either a class E RF amp or a class C tube RF amp.  The pulse width modulators behave identically in either case as well.

THIS IS NOT A CLASS E THING.  This is an individual transmitter thing.  Tube, solid state, DYY design, QIX design... it is NOT a class E thing.

You can pretty much make any technology (tube or solid state) do pretty much the same thing.  Having built quite a few PWM transmitters from tubes and MOSFETs, I can tell you with absolute certainty they do exactly the same thing.

As far as my designs are concerned, I could "dumb them down" to match some of the other offerings out there, but I have been leaving those decisions up to the operator.  I do offer much tighter filters, and the designs are published, and the parts are available as part of a PWM class E kit, if desired.  All of my designs are capable of reduced frequency response, but again, that is up to the operator.  I only say all of this because the majority of the class E transmitters out there are of my design, and that design provides a robust, high capability platform.  What the operator does with it is an individual thing.  Kind of like buying a high performance car.  The operation of that car is up to the driver.

Regards,

Steve
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WA3VJB
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« Reply #103 on: November 12, 2009, 02:57:50 PM »


"Thrown around" yes, and handed to them by those who want to substitute quantity instead of quality as a measurement standard.

Dave said -
Quote
The point of my post is bandwidth numbers are thrown around by hams as if they were finite values like counting bricks.
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WA1GFZ
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« Reply #104 on: November 12, 2009, 02:58:17 PM »

man, 5 pages of beating a dead horse.
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KF1Z
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Are FETs supposed to glow like that?


« Reply #105 on: November 12, 2009, 03:05:17 PM »

man, 5 pages of beating a dead horse.


To a bloody, quivery, gelatinous mass.
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Pete, WA2CWA
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« Reply #106 on: November 12, 2009, 03:08:51 PM »

man, 5 pages of beating a dead horse.


Not a uncommon occurrence. We can probably do 20 pages on how to cook a steak on a grille.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
Steve - WB3HUZ
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« Reply #107 on: November 12, 2009, 03:20:44 PM »

Yea, quit bad-mouthing Class E. Move on to Class F already.


* beatdeadhorse5[1].gif (8.67 KB, 65x78 - viewed 895 times.)
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ke7trp
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« Reply #108 on: November 12, 2009, 03:23:50 PM »

Cooking steaks.. Hmm.  Going to Grill up some tonight.


Clark
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W3RSW
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Rick & "Roosevelt"


« Reply #109 on: November 12, 2009, 03:54:06 PM »

yeah!
What's for dinner net.

Beating right along,  ...(hmm, steaks sound good.)
Check out this bad boy.

Quote
Wouldn't the actual program material make a difference as well ?  IE :Processed snare drums and cymbals VS a James Earl Jones voice over ...
Sure.  The changeover to cymbals and rock from voice programming shows up half way down the waterfall.


* WMMN.JPG (134.13 KB, 943x701 - viewed 946 times.)
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RICK  *W3RSW*
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« Reply #110 on: November 12, 2009, 04:15:23 PM »

the subject of AM bandwidth always seems to get most AMers bowels into an uproar! Especially the thought of legislated bandwidth limits.

All I got to say is one of the reasons I'm on Am and not on SSB is simple"
"Why have hamburgers when you can have steak"
And speaking of steak and the "Whatz fah dinnah net" I'll have to call the war dept and see Whatz fah dinnah  Grin  Grin

                                                   The Slab Bacon
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"No is not an answer and failure is not an option!"
W3RSW
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Rick & "Roosevelt"


« Reply #111 on: November 12, 2009, 05:17:45 PM »

better yet, let's fire up on 3733.

last one in's a rotten egg.

Later-
fired up the 813's rig, made a couple of calls and then just realized that the entire east coast is socked in from Ida, lightning and all.   AHE's probably unhooked all his antennae, etc.
....oh well

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RICK  *W3RSW*
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CW is just a narrower version of AM


« Reply #112 on: November 14, 2009, 11:34:11 AM »

Ride this horse!

The 10 kHz spacing on the BCB guarantees adjacent channel interference. That is why they skip a few channels in local coverage areas. 10 kHz is not enough even with legal AM if you are talking HiFi.
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These are the good old days of AM
kg8lb
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« Reply #113 on: November 14, 2009, 12:02:39 PM »

Ride this horse!
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