Deadkey vs swing

[HomerBB]

and again, LOL

 

[packrat]

I have caller ID, so I don't answer those kinds of calls.

 

[Simbalage22]

Ok.. NOW I AM CONFUSED!! Coil power Cobra 25LTD

I got a 25GTL.. According to what I have learned here, you dont spead coils for power! Then why does all tuts on this cobra 25GTL say 25 VR5 or Cut D9

L13 L10 L9 L8 Some of these are the coils. AND the others the slugs are missing. There is a cap/Resistor on jp6 which if memoy serves me is should just be a jumper on the cobras.. Whats right? I knew I have read (which remids me of my NWST Cobra) same practice to spead and tune coils... Ahhh I am undoubtfully lost now

 

[BOOTY MONSTER]

Christ.

Your satire / this thread is the perfect example of why I gave up on CB.

-Richard-

YouTube - ‪Ricky Nelson - Garden Party 1972‬‎

 

[74IN]

For CB radios, I do clip. I'm a bad fishy.

It simply gives the operator the control to regulate modulation. If you are a "all knobs full right" type, don't do it. Many unmodified CB's give only about 80% mod, and many try to use "power mics" to correct that in vain.

On the rigs in the big trucks, I use noise canceling mics and the ability to control the mod helps. Clipped, I find I do well at about noon to 1 o'clock on the mic gain. Turn it more than that and you overmod and sound like channel 6.

As far as a radio with a low DK and alot of swing goes, that works well when using an amp if the end result is a 1:4 ratio. At least in my experience.

If you have a very low DK with alot of peak, it's borderline DSB (double side band). It will sound horrible while you fixate on the big needle swing.

 

[Simbalage22]

For CB radios, I do clip. I'm a bad fishy.

It simply gives the operator the control to regulate modulation. If you are a "all knobs full right" type, don't do it. Many unmodified CB's give only about 80% mod, and many try to use "power mics" to correct that in vain.

On the rigs in the big trucks, I use noise canceling mics and the ability to control the mod helps. Clipped, I find I do well at about noon to 1 o'clock on the mic gain. Turn it more than that and you overmod and sound like channel 6.

As far as a radio with a low DK and alot of swing goes, that works well when using an amp if the end result is a 1:4 ratio. At least in my experience.

If you have a very low DK with alot of peak, it's borderline DSB (double side band). It will sound horrible while you fixate on the big needle swing.

Ok so clipping is ok when someon can verify that your dynagain (on cobra) isnt too high? Thanks for that.. very inspiring.. Was thinking of adding a switch for it off (clipped) and on... also there is a cap and diode isnt that to lower the dk? and could I just put a swith to basically byspass that for higher deakey, and enable it for lower? aka have the switch just connect the circuit as if the jumper were there?

 

[Simbalage22]

Your current set up is just right and it is sound good. Leave it alone.

So where'd that "to swing or not to swing thread go?" Y'all know...that one that was as long as a book and all kinds of people were getting killed over it? Man....that thread cost thousands of lives and millions of dollars ! {Animal House}

I found that thread... And this one makes WAYYYYY more sense....

 

[Simbalage22]

It seems to me there should be some clarification here between the coils (inductors) used for impedance matching and the inductor used for the 54 MHz trap. The first RF inductor off the final collector is to match the low collector output impedance to 50 ohms. It is correct to adjust this inductor for maximum PEP output and this will not increase harmonics. The second inductor is just a simple 54 MHz trap and should never be adjusted without the ability to measure a reduction in RF content at 54 MHz.

Now this is my question.. As for dk vs swing, I am confident that 1/4 of power should be DK, and the rest swing, However this trap thing.. how come the cobra 25 mods are to spread the coils, as well as tune pots? I have been told on this form never touch coils so whats right? This new radio has a cap/resistor and is only DK at 1w and swings to like 20 isnt that bad?

 

[Simbalage22]

Tell me this, when you are using the amp with that 2 watt deadkey from the radio, what does the amp deadkey without modulation? It should be around 45-55 watts. If it isn't, adjust the radio deadkey up or down until you get it somewhere in that range.

High deadkey with small swing=undermodulated (bad). Low deadkey with huge swing is overmodulated (also bad). Deadkey at 1/4 of full modulated power is just right. You are pretty close to that now (a little over) but since you are running an amp, a little more swing will probably be ok.

But check what the deadkey coming out of the amp is with no modulation, and let us know what that is.

Well after comming back to this, I picked up a cheap patch cable to connect after the power from amp.. if its wide open and the dosy is set to 300 I see a deadkey around 100 and swings to 200.. If I turn it to variable and 30... It is where I usually use it, its around 5w swinging to 100.. But what I noticed it with the meter connected the amp @ full actually starts to click, possibly due to the cheap cable, or something with ps.. With antenna direct to the amp it doesnt click, but dims as I talk.. The PS is tinma 30AMP

 

[Simbalage22]

Someone PLZ REad Me..Deadkey formula!!!

Well I connected that cobra 25 to the meter, and was yacking ALL night.. the way it was modded... shows about 50w deadkey swinging to 250w with amp... So here is my question.. I know now with the amp that 142 needs a lower deadkey because its @ 100W deadkey.. However with the 25... does the 1/4 power rule apply when running barefoot too? if so 1 watt deadkey would be too litttle with it swinging to 10 right? Should it be more near 2 1/2 watt deadkey swinging to 10... I only ask because ppl say its clear (Without limiter clipped) just turned up, and the amp...but what about barefoot.. I use that formula.... 10 x 1fourth and get 2 1/2 w... as with the amp... 250W x 1fourth = 62 1/2 am I doing this right?

 

[Carl]

1/4th key always applies to a properly modulated am signal. try to achieve the same key to power relationship when running an amp or not.

the coils are tvi traps, by spreading them you increase the amount of harmonics. dosy, and other cheap meters cannot tell the difference between power that is on frequency or not. this is another reason that low pass filters get a bad rep, some people think the reduce your output by running them when in reality they only reduce the out of spectrum harmonics that your meter is reading.

good practice is to run one before your amplifier and possibly after if you can find one with the proper wattage handling capability's. generally you want a better one as the cheap ones don't work as well.

 

[Simbalage22]

1/4th key always applies to a properly modulated am signal. try to achieve the same key to power relationship when running an amp or not.

the coils are tvi traps, by spreading them you increase the amount of harmonics. dosy, and other cheap meters cannot tell the difference between power that is on frequency or not. this is another reason that low pass filters get a bad rep, some people think the reduce your output by running them when in reality they only reduce the out of spectrum harmonics that your meter is reading.

good practice is to run one before your amplifier and possibly after if you can find one with the proper wattage handling capability's. generally you want a better one as the cheap ones don't work as well.

thanks carl, so thats why those are in tuneups to see more watts LOL.. Now we are getting somewhere...

As my example a cobra 25 with 10w peek.. Isnt this where it should be?

Without an amp..Thats 10 watts so..

10 x 1/4 = 2 1/2 watts DK



With my TX 250HDV Amp..Thats 250 so..

250 x 1/4 = 62 1/2 watts DK


BKA.. Barefoot this radio should DK 2 1/2 watts swinging to 10, and
With my amp show 62 1/2 DK, swinging to max Correct?


now this is where is all gets tricky, so people understand my point. Someone posted that this amp should be within 45-55w of deadkey.. This 25 has a cap/resistor (Swing kit)... giving me less then 1w of carrier, and swinging to around 10...(barefoot) That would be bad if the info here is right, because alone this is not 1/4.. Too low, But However when running the amp with this config its around 50W Deadkey, swinging to around 250....

The 50 calculated here from what I am guessing is assuming the amps peek is 200, so its not working as hard.. so

200 x 1/4 = 50.... giving that radio the magic safe operating range WITH a swingkit... So I started a thread asking about the swing kit... With this swing kit the radio is off barefoot, but dead on 1/4 rule with the amp


Good response about that tvi misconception, as that alot of guides miss

 

[Carl]

your ts250hdv is rated at 150w peak with 4w input, 250w with 20w input (@26amp per texas stars testing) 175-190 is generally all you see, keep in mind that when you double your power you see 1/2 a s-unit increase or 3db. you would need to go from 150w to 600w to see just 1 full s-unit. that's why i try to recommend a 4 transistor amp run on low, it will be cleaner than a 2 transistor amp running at the same power levels.


Texas Star Export Feature Chart

 

[Simbalage22]

ok taking this new info into account. the amp can still max out to 250W... so if the radio has the swing it can get to 20W in...

I dont understand with this cobra 25 the dosy "sees" 200W.. with the swing kit..


So if I throw 4 watts in I get 150 out... So where does the swing play a role in all of this?

 

[loosecannon]

the truth is, you just cant really trust most wattmeters to be accurate.

try this, assuming the limiter diode in that 25 has not been clipped; turn the modulation pot down until you see a 1 watt deadkey swinging to about 4 or 5 watts on your dosy.
the mic gain on the front of the radio should be all the way up.
make sure that you have put the trap coils back the way they were before you do this.

now try it with the amp.
what does the amp put out now?
LC