scope pattern

[K5IIA]

i have heard about the shark fin look on the scope and was wondering if this was kinda closee to it. the top is just a tad flat but i do see a fin off to the side of it.

 
http://www.youtube.com/bspn33#p/a/u/1/vJYB5wVNVdc

this was recorded off the if output of a r390

[W2PFY]

I just love that audio How can i get some

[W1RKW]

Back swinging the monkey!

[flintstone mop]

ohhhhhhhhhh nooooooo Mr Bill!!!!

Looks like it's out of phase and no high frequencies.
If you are using a professional microphone, you can reverse the leads. If you're not running balanced audio to the TX, You can reverse the plate leads on the modulator tubes AFTER THE TX IS OFF AND HV DISCHARGED.....
Sorry for loud voice.

Any EQ used? Usually the settings resemble a smiling face, somewhat.

This link is a better representation of a well modulated TX

http://www.youtube.com/watch?v=pvowzE_XYl0

You modulation looks like out of phase.
Listening sounds like a transistor audio amp and the bias set wrong. audio choppy and extreme distortion.
Modulator tubes bias set up properly??
You're moving along and making AM
Fred

[WA3VJB]

http://www.youtube.com/bspn33#p/a/u/1/vJYB5wVNVdc

The guy on there is among those who taught The Derb how to Swang a Munkey. just FYI.

[K5IIA]

i remember a vid that derb did on youtube i wish was still on there. i forgot what amp it was but he was tuning it with the watt meter and having some fun with it. 

[WA1LGQ]

Looks like the good buddy was using a class C "linear" amp.

[KX5JT]

While we are on the subject, here is my scope pattern on the newly acquired Viking II.
Do I need to add a negative peak limiter?

http://s271.photobucket.com/albums/jj131/kx5jt/?action=view&current=scope.mp4

[Steve - K4HX]

That or turn down the mic gain. Also check your audio polarity.

[w5omr]

That or turn down the mic gain. Also check your audio polarity.

Agreed.

Where the pattern expands above and below the base line are the Positive peaks.  the Negative peak is where the plate voltage is reduced to 0 in the final.  You've got too much audio.

As Steve suggested, check the audio polarity, as well.  Might be the plate caps on the 807's. 

To see how much positive audio you do have in that rig, I'd suggest adjusting the carrier to the point where it consumes 2 divisions on the graticule, then talk to it.  100% will be when the positive peaks reach 2x as high as the carrier, at the same time as the carrier is pinched at the baseline (and not that long line between peaks which represents OVER-modulation).  Make note of where your pattern peaks are.  This establishes a reference point. Make your changes, and check it again.  With the carrier consuming 2 divisions, at 100%, your peaks should reach close to 4 divisions, up/down from the base-line.

Also, I see some hummmmmm on the carrier.  That's probably being picked up by the scope being near an AC field of a transformer. If the Scope is on top of the transmitter - not a good idea.  Or, it's the single lead inside your tuner-box that's getting hum induced into it.  This is why I suggested sampling RF out in the field of the antenna.  Probably best to use some RG-58, run it outside, and make a loop in the coax of a few feet, and lay it on the ground, or hang it in a tree, or something.

Here's what I was able to capture, so you know what I'm talking about..

That solid line between the patterns, is over-modulation.  that's the base-line and shouldn't be cut off like that.

Your carrier consumes 4 divisions on the graticule of the scope.  Your peaks should not be rounded off at the tops (means you're flat-topping - not enough audio voltage and/or reversed audio lead/plate-leads on the modulator), and should consume ~8 divisions, without pinching off the carrier (like the picture shows).

Hang in there, John!  We'll get ya straightened out, yet! :-)

[KX5JT]

Thanks Geoff.  I knew I was overmodulating.  As you see I do put the carrier for the center half of the scope (2 divisions above and below the centerline).  I am hitting the top and bottom pretty easily. 

The problem is when I drop the audio on the front panel to the point where the there is no white lining (or flatlining like I like to call it), then the positive peaks barely make it to the 70% level.   It just don't look pretty. 

I'll try swapping the plate leads on the 807's tommorow night when I'm back in the shack.  Although they look like they belong to each tube they are on, I have read that vocal symmetry can vary from person to person.  Can't hurt to try it.

[w5omr]

Thanks Geoff.  I knew I was overmodulating.  As you see I do put the carrier for the center half of the scope (2 divisions above and below the centerline).  I am hitting the top and bottom pretty easily. 

Well... I set mine to 2 divisions (one above, one below).  SOMEwhere around here, I have a video of it and need to capture a screen-shot and show you why I need only 2 divisions for the carrier... it's because the audio is pretty much going off the top and below the bottom of the screen 
[quote
The problem is when I drop the audio on the front panel to the point where the there is no white lining (or flatlining like I like to call it), then the positive peaks barely make it to the 70% level.   It just don't look pretty. 
[/quote]
It's FAR better to be UNder-modulated than OVER-modulate like that, when it comes to keeping peace with those that share our spectrum, and not necessarily our views.

In other words, if you don't want the wrath of some SillySideBander coming up and saying "hey, man!  Yer splattering all over the band!" because, well... he'd be right and then there starts the war.  If we don't give 'em a reason to bitch in the -FIRST- damn place, we can help keep the bad feelings down to a minimum.

Besides, it's the right thing to do (not over-modulate, that is).

As far as getting the positive peaks up there, yeah.. check the polarity of the microphone, and the plate-caps on the 807's.  When Jerry put the Valiant mod transformer in there, they might have gotten reversed.  (not knocking Jerry's technical ability - I've done the same thing)
[/quote]
I'll try swapping the plate leads on the 807's tommorow night when I'm back in the shack.  Although they look like they belong to each tube they are on, I have read that vocal symmetry can vary from person to person.  Can't hurt to try it.
[/quote]

It does vary from person to person.  Female voices are -most- difficult to manage!  You could always monitor the output of your microphone with your voice on your scope.  That'll give you an idea of what YOUR voice patterns are like.

[k4kyv]

A trick I use to get more detailed resolution with my scope is to set the base line right at the bottom of the screen, not midway up towards the top.  The envelope pattern by definition is symmetrical, so the top half is inevitably a mirror image of the bottom half.  Move the sweep line down to the bottom of the screen and double the vertical gain (or halve the attenuation) so that the pattern once again fills the screen, and you will get a closer-up view of the envelope pattern. You may want to also double the sweep frequency to keep the shape of the pattern the same.

[flintstone mop]

A trick I use to get more detailed resolution with my scope is to set the base line right at the bottom of the screen, not midway up towards the top.  The envelope pattern by definition is symmetrical, so the top half is inevitably a mirror image of the bottom half.  Move the sweep line down to the bottom of the screen and double the vertical gain (or halve the attenuation) so that the pattern once again fills the screen, and you will get a closer-up view of the envelope pattern. You may want to also double the sweep frequency to keep the shape of the pattern the same.

I'll check that out Don...........Looking at both sides enables me to determine if the modulation is out of phase. Just looking at only half might not reveal phase............i'll do some lookin'
Fred

[KA2QFX]

As funny as it is to hear these clowns tear up 27 MHz, what's funnier is the worse they sound the more they tell each other they sound good... as long as they're loud. 

I think those are Guppy Fins you're seeing.

Mark

[K5IIA]

I can tell I'm out of phase when I hit the baseline before I modulate 100 percent positive.

[KX5JT]

I think I might build a project box with a dpdt toggle switch labeled Phase Reversal and put it in line.

I like that technique Don.  I just tried it.

[Steve - K4HX]

Beats getting inside the TX and switching plate caps!

I think I might build a project box with a dpdt toggle switch labeled Phase Reversal and put it in line.

I like that technique Don.  I just tried it.

[KX5JT]

Beats getting inside the TX and switching plate caps!

No, that would be much easier BUT I also have other rigs, including a DX-60 that could benefit from using a project box, there are no push pull modulator tubes in that rig or in my ts-570 Steve.

[Steve - K4HX]

Yep. Put the box in line at the point where your outboard audio gear feeds the transmitters. Should be FB.

[k4kyv]

As funny as it is to hear these clowns tear up 27 MHz, what's funnier is the worse they sound the more they tell each other they sound good... as long as they're loud. 

I hear the same thing all the time on the ham bands when I tune in slopbucketeers.  I hear some of the nastiest, raspiest crappiest sounding audio imaginable, and the other guys in the QSO tell him he "sounds good".

[KX5JT]

As funny as it is to hear these clowns tear up 27 MHz, what's funnier is the worse they sound the more they tell each other they sound good... as long as they're loud. 

I hear the same thing all the time on the ham bands when I tune in slopbucketeers.  I hear some of the nastiest, raspiest crappiest sounding audio imaginable, and the other guys in the QSO tell him he "sounds good".

Sadly I hear it too on A.M.  --- Give me an HONEST report, because that's what you're getting from me!

[k4kyv]

Sadly I hear it too on A.M.  --- Give me an HONEST report, because that's what you're getting from me!

You're five-nine. I say again, five-nine!  Now please repeat your call sign several times. I can barely hear you through all the noise, and the QRM is covering up your signal... You're five-nine.

[KX5JT]

Sadly I hear it too on A.M.  --- Give me an HONEST report, because that's what you're getting from me!

You're five-nine. I say again, five-nine!  Now please repeat your call sign several times. I can barely hear you through all the noise, and the QRM is covering up your signal... You're five-nine.

Thanks Old Man you're 59 too, gud luck in the contest!

[Steve - K4HX]

Almost no one give out correct reports compared to the definitions below.

An S9 would hardly ever be given. Many R3 and R4 reports would also be given, even though the guy on the receiving end is getting 100% copy.

R = READABILITY
1 -- Unreadable
2 -- Barely readable, occasional words distinguishable
3 -- Readable with considerable difficulty
4 -- Readable with practically no difficulty
5 -- Perfectly readable

S = SIGNAL STRENGTH
1 -- Faint signals, barely perceptible
2 -- Very weak signals
3 -- Weak signals
4 -- Fair signals
5 -- Fairly good signals
6 -- Good signals
7 -- Moderately strong signals
8 -- Strong signals
9 -- Extremely strong signals

T = TONE
1 -- Sixty cycle a.c. or less, very rough and broad
2 -- Very rough a.c. , very harsh and broad
3 -- Rough a.c. tone, rectified but not filtered
4 -- Rough note, some trace of filtering
5 -- Filtered rectified a.c. but strongly ripple-modulated
6 -- Filtered tone, definite trace of ripple modulation
7 -- Near pure tone, trace of ripple modulation
8 -- Near perfect tone, slight trace of modulation
9 -- Perfect tone, no trace of ripple or modulation of any kind