The AM Forum

vine.co/v/eiY0L3w9VlV (http://vine.co/v/eiY0L3w9VlV)

(you may need to click the volume 'on')

Jon
KA1TDQ

Takes two to tango, will the receiver on the other end know the difference? Give me mid range & highs, I can hear you. Percentage of mudulation......10% sucks wind...............close to 100% gets the job done...........anything more is just for the operator of the 150% transmitter. 

At times that broadcast audio (bass) comes thru like a muddy turd. Then my transmitter is not even turned on.............


Craig,

As has been discussed on here before, good high levels of average modulation is more effective at getting through than falling all over yourself for 150% modulation. Knock yourself out.

BTW, 600 watts output carrier on AM at !00% modulation, equates to 2400 watts PEP output, as the FCC would measure it. 1500 watts PEP output is the max legal limit isn't it??? You can do the math on the 600 watt carrier output, if you want to modulate that at 125 or 150% modulation. Have a good dummy load.

Al VE3AJM

it just has some video of a girl and no audio and no audio buttons.

If you run the mouse over the video while it's playing, you will see a little speaker icon in the upper left corner.  On my computer, it was "x'ed" out. Clicked on it and the audio played.  I didn't notice it immediately either.

  I am attaching a letter written by the late Hoisy Hoisington, W4CJL, Founder and Chairman of SPAM.

You might find this interesting.

Jim
Wd5JKO

I watched that clip for two hours and now I know more about justice than she does but know nothing about 150% modulation! Funny how one little clip can spark such a debate? I sometimes run over 160% or possibly more into my dummy load just to be bad. I don't do it on the air for fear of the modulation police  ::) ::)

I run over in Arizona, but I'm living in the Wild Wild West.

https://www.youtube.com/watch?v=wk4QqIeZ9Xk (https://www.youtube.com/watch?v=wk4QqIeZ9Xk)

JR

What does modulation approaching and greater than 100% get you?   Distortion in my B.A. receivers!   Don't do it. ;)

Some of he guys in N.E. are running about 500% modulation with some sort of PMS modulation scheme and I have no problem copying them on my R-390A receiver. I thought it was only modern solid state receivers that had a problem over a certain percentage? Is it true that if you take a fresh wet river rock and drill very fine hole in it,attach fine wires to it, you can make a transister? My experiment with dry rocks didn't work!

I always got good reports with my GRC-106. It usually made a 50-60W carrier and 400W PEP and that was apparently its stock behavior.
The situation may be different with it because it used "AM Equivalent" mode sending only the upper sideband with the carrier. There were no complaints about distortion or AGC deception.

Normally I use the plate modulated transmitter and try to keep positive peaks regulated to 100%. There are never any complaints on that set.

There is one person on the RT who uses a diode scheme on his plate modulated set to go >100%, but it does not bother me on my receiver, a 75A-2 in which the AGC release time has been increased to two seconds by adding a capacitor on the AGC line. The result is that he is louder-sounding with it, but then he has only got a 120W carrier so it helps me hear him rather than being an annoyance.

There are the articles where the carrier is run up to a high level and the modulation is greatly negative. In some tube data, it says that for class C "CW" data, that modulation essentially negative may be used as long as the positive peaks do not exceed some small value, 5 or 10% IIRC.

Modulation effect on the receiver is not only about the amount but the balance between positive and negative. The more asymmetrical it is, either way, the more it seems to wiggle the AGC around on the other end. Boatanchors that don't have product detectors get messed up by unusual schemes, and some are more affected and some less as far as what comes from the speaker.

Is the discussion also partly about whether the listener's receiver is delivering audio that sounds like the sending person is in the room with you, or delivers sound that reminds one of the CB band on Saturday night?

While standard broadcast-like operation works with all receivers, there are too many variables to expect that "modulation experiments" will be heard nicely on all receivers.

Once I heard broadcast-quality AM through a receiver with a flat 15 kHz filter and low-distortion detector and audio system, my point of view on stock 1950s - 1960s boat anchor receivers changed forever. For me, this happened years ago with a modified Racal. For others these days, it often happens with SDRs. But the effect is the same.

Here's an example (from a modified Racal RA6790):

http://liberty.3950.net/WA3VJB%207290%2020k%20bw%2020110320%200317PM%20ET.mp3

and another (from an SDR-1000):

http://liberty.3950.net/WA1HLR%20W4BVT%20et%20al%20early%20AM%2020141119%203885%20kHz.mp3

The improvement in audio -- and the ability for the operator's voice and personality and subtleties of expression and meaning to come through -- was, for me, much greater going from stock AM to high fidelity AM than it was going from stock communications SSB to stock communications AM.

73,

Kevin, WB4AIO.

Yes, it depends a great deal on the receiver -- and on the preferences and expectations of the listener.

AME (single sideband with carrier) has an inherent distortion of about 35% at 100% modulation, when heard on a diode detector. The fact that some don't complain about this is interesting; possibly their receivers already generate distortion that masks that coming from the inherent AME behavior. But that distortion disappears completely when a synchronous detector is used.

It's the same with stations that utilize very high positive peaks. Those who generate this kind of signal using natural asymmetry (and have clean modulators) sound perfectly clean on a sync detector, but generate some distortion on most commercial diode detectors. Those who generate this kind of signal using asymmetrical clippers or other diode schemes create some inherent distortion that can't be remedied at the receive end. How tolerable this distortion sounds depends on the ears of the listener and his expectations, the degree to which his receive setup generates its own harmonics and intermod, and also how "bright" the transmitted audio is. Stations with a lot of audio energy in the 3 to 10 kHz treble range tend to mask such distortion and make it more tolerable.

73,

Kevin, WB4AIO.

Kevin,

???? Are you suggesting the purchase of special/new equipment for listening to encrypted 150% mudulated audio? Not going to happen at this QTH! If I wanted to listen to encrypted audio..............maybe that of law enforcement transmissions ;D

Here in Orygun there are grow lights East of me, grow lights West of me.......afraid to look over the backyard fence, might be grow lights back there too. The WeedQRM is no less than S9. Most of use poor hams that aren't into growing weed can't afford more radios. Give me sumthin around 100% mod........with mid range & highs. Then I'll light up transmitter.


Craig,

That's it Craig! I can handle the 150%ers but what I can't stand is the 50%ers!!
Nothing bugs me more than an S9+ carrier with no audio.

This is fun ;D............hot here in Orygun & the shack doesn't have AC.

We try to help those that don't have an o'scope in line with the TX. Tell'um to crank up the audio gain till they tickle the base line.

Craig,

Even worse, an S-3 carrier with 50% modulation - - with an old buzzard transmission   ;D

Al

...and through a vintage carbon mic they picked up at the last hamfest.

Jon

Al,

Now you are talking bout me & others. I had a DX-40 once. ;D

Craig,

Debate? WTF? What is there to debate? People run what they run. Have a QSO with them or not. Life's too short to argue about stupid stuff.

who you calling stupid??

Now at 150% : WHO YOU CALLING STUPID?

 ;) :o

I thought that was only legal in Colorado (seriously)...legal in your state too?  They kept it quiet. CO made a big deal about it.

"A measure to legalize recreational use of marijuana in Oregon was approved on November 4, 2014, making Oregon only the second state to have legalized recreational marijuana."

And you thought that a satellite shot of Oregon showing lots of cloud cover was just burning forests.

It will most likely take a SCOTUS decision to make it legal in the rest of the states.

Jon

 ;D

gonna need a hepa filter for the smoke & odor.

Craig,

Carbon charcoal filters are the ones of choice.

It is legal to grow your own I  a lot of the state's that have medical laws.   Here in California,  it's a county by county limit.   I believe Kern,  the county I live in,  is the lowest.   They have been trying to close the shops for years, drags on and on in the courts.

--Shane
KD6VXI

A dope named GRUBER called us stupid too

Fred