I have a Question about "Dead Key" and "SWING"

[Bow]

I have been playing with radios for the better part of 20 years... I'm a HAM, Avionics Tech (by education and trade) and a 11 meter Op...

But what is this Dead Key and Swing thing?

Dead key: Un-modulated Carrier

Swing: Modulated Carrier (Peak to Peak)

If you have a stock CB that has an Un-modulated carrier (Dead Key) of 4 watts and a Modulated carrier of 16 watts PEP (Swing?), you then have 100% modulation...

If you have the same radio modified for say... a 2 Watt "Dead Key" and 37 Watts of "Swing"?

Wouldn't you have a lot of over modulation,splatter, and the ability to to get a "Worked all Toasters" award from your neighbors?

What is the point of a low "Dead Key" and a big "Swing"

Someone please educate me on this...

 

[W5LZ]

Oh, I think you've probably already got the education. It's the other ones who need it.
- 'Doc

 

[Moleculo]

"Worked all Toasters"



That's awesome. I'm going to use that one.

The only reason I can think of why people want to do this is so they can drive the snot out of a transistor amp that can only handle a carrier of a couple watts. Of course the transistors used in that amp was probably never designed to driven like that either, so in the end you get to work even more toasters.

 

[gc505]

What is the point of a low "Dead Key" and a big "Swing"

Someone please educate me on this...

My guess is so that they don't sound like the tired, quiet hams on 10 meters. If that's what they wanted I'd imagine they'd at least get a tech ticket and hang out in 28.3-28.5 Mhz.

The overmodulated splatter has become a 11 meter trademark, especially with the "power boys" (and wannabe power boys) of CB.

I'm a very active ham (W9SFA) and I'm also very active on CB, and I'm proud of my screaming loud, overmodulated signal on that band, because it fits in with the others. But when I get tired of hearing overmodulated, crappy signals (like mine) I go catch a QSO on any of the HF bands where it's (sometimes) more civil and the signal quality is often unsurpassed.

We already know what the 11 meter band is - and what it isn't. It's effectively the unregulated ghetto of the HF spectrum. I guess that makes me a part time, 11 meter ghetto rat.

Wouldn't you have a lot of over modulation,splatter, and the ability to to get a "Worked all Toasters" award from your neighbors?

I love the terminology!

 

[Captain Kilowatt]

I don't care what band I operate on I absolutely refuse to have an over modulated splattering signal.



Well there was that ONE time I tried out my Heath DX-60 on 11m. That 12 watt carrier grid modulated to 50 watts caused quite a ruckous for several channels either way and I did get a little kick out of it but I quickly came to my senses. :laugh:

 

[W5LZ]

'WATT' = Worked All Them Toasters
'WAHA' = Worked All Hearing Aides
'WATF' = Worked All Teeth Fillings
'WACS' = Worked All Computer Speakers
'WAS' = Worked All Stereos
and the really hard one,
'WACCS' = Worked All Car Computer Systems

All the above require documentation for confirmation.
- 'Doc

 

[Captain Kilowatt]

'WATT' = Worked All Them Toasters
'WAHA' = Worked All Hearing Aides
'WATF' = Worked All Teeth Fillings
'WACS' = Worked All Computer Speakers
'WAS' = Worked All Stereos
and the really hard one,
'WACCS' = Worked All Car Computer Systems

All the above require documentation for confirmation.
- 'Doc

You forgot WHAT= Worked Hardly Anything 'tall ('tall=at all) Usually because they can't understand you and keep saying "What? What?"

 

[Bionic Chicken]

Years ago I had a 4-1000 amp and lived in the city. I would wait until after midnight to key it to limit RF interference with toaster, etc. My next door neighbor came over one morning and asked if I had been on the radio earlier in the day. I told him yes. He said he figured so because around 3 am he heard some racket in the front room of his house and went to investigate. He found the coffee pot (that had been set on a timer) brewing coffee an hour and a half before the set time. After doing a little testing we found I could not only turn his coffee pot on but could also make his VCR come on and start recording. Luckily he was a decent fellow and it was not a big problem.

 

[freecell]

"What is the point of a low "Dead Key" and a big "Swing"...."

conservatively speaking it started out as a method by which 4:1 peak-to-carrier could be produced by an amplifier driven well beyond the middle of its power output range whereas most well designed amplifiers will mimic the ratio established by the transmitter almost exactly if not excessively driven.

as time passed by it just turned into stupid.

if anyone is still confused about the proper peak-to-carrier power relationship of an am transmitter just visit the chart in the middle of the page linked to below.

Transmitter Power & Harmonic Line-Section OverSampling

 

[Bow]

I don't care what band I operate on I absolutely refuse to have an over modulated splattering signal.

EXACTLY!

I have never quite figured that out.. I love the "Break 19 for a Radio Check!"

"Well, your over modulating, very tinny, sounds pretty rough... roll your mic gain down..."

The reply is usually... "What?"

 

[Radio Tech]

EXACTLY!

I have never quite figured that out.. I love the "Break 19 for a Radio Check!"

"Well, your over modulating, very tinny, sounds pretty rough... roll your mic gain down..."

The reply is usually... "What?"

I just tell em, "You are getting out, I hear ya on at least 10 channels"

 

[Bow]

hahahhahaha

But down here around Houston, those guys usually speak Spanish.... on 5-6 channel either side of the channel they are on...

 

[Radio Tech]

In that case:

I just tell em, "Usted está saliendo, yo oye ya en por lo menos 10 canales"

 

[dudmuck]

If you have the same radio modified for say... a 2 Watt "Dead Key" and 37 Watts of "Swing"?

Wouldn't you have a lot of over modulation,splatter, and the ability to to get a "Worked all Toasters" award from your neighbors?

the 4:1 ratio for 100% modulation applies to symmetrical AM.
Where symmetry means the peak reduction in power (due to modulation) is the same as the peak increase in power.
Because with AM, modulation is alternating reduction and increase in total power.

Where you get into trouble is when the reduction in power attempts to go past zero power. This hits like a hammer on a nail, meaning its abrupt and wide in bandwidth. This is splatter.
On the opposite end of the cycle, the increase in power, the modulation can exceed 100% with a only tiny increase in distortion. To be loud, you dont want more on the negative side, only more on the positive.

Over negative modulation is a problem with radios and swing kits.
Positive side modulation becomes an issue with power amplifier transistors only able to put out limited power.

 

[W5LZ]

dudmuck,
You're right, as far as you are going with it. But, the fact remains that that dip into the 'zero power' portion of the 'negative side' is still a result of over modulation. It might be more noticeable than a slight excursion on the 'positive' side. But so what, it only indicates that the whole thing is being over modulated, driven too hard, and you still lose quality or fidelity of the signal. No real benefit to a 'single sideband with carrier' signal. Might as well go that extra step and make it 'single sideband with no carrier'. Imagine that!
- 'Doc