Some distortion? Sometimes it helps, but eating Doritos while talking?
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Negative Peak Compression boards for Cobra 29
- Thread starter FredTx63
- Start date
I have to agree with you guys. It’s whatever sells radios. To most it’s good sounding audio. You have your talk on three channels at once guys. We have the do it yourself guys that have everything perfect on the scope. There are the guys who made their own mods to sell. There are guys that replace the new components in out of the box radios. There are guys with their perfectly tuned bench. In the future we may see radios that were tuned with tools blessed by Voodoo Witch Doctors. A radio tuned in a dressing room of a strip club so it will always smell like vanilla perfume and Coors Light. And then CBs upgraded with parts from the Roswell New Mexico UFO crash. It’s a big market. People prefer what makes them feel good. A good sounding radio does just that.
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I have watched that twice.
What's going on with the peak reading meter?
The before reading looks better on the peak meter that the after unless my old eyes are fooling me.
What do you think?
73
Jeff
What's going on with the peak reading meter?
The before reading looks better on the peak meter that the after unless my old eyes are fooling me.
What do you think?
73
Jeff
At 3:28
Stock...
At 5:10
Still Stock
At 17:02...
Now installed...
At 17:37...
Keyed up with Carrier ON LOWEST SETTING (ON Board pot)
At 18:11...
Still on LOW POWER Setting...
at 19:53...
There's something we need to talk about...
The above is LAG from Limiter and Mic (AMC loop)
More Detail...
No - PEP is LOWER!
@AudioShockwav - you're right!Stock...
At 5:10
Still Stock
At 17:02...
Now installed...
At 17:37...
Keyed up with Carrier ON LOWEST SETTING (ON Board pot)
At 18:11...
Still on LOW POWER Setting...
at 19:53...
There's something we need to talk about...
The above is LAG from Limiter and Mic (AMC loop)
More Detail...
No - PEP is LOWER!
There are several conditions happening here.
When you "turn down the carrier" - remember where the LIMITER is located - up stream from JP36, what you, the viewer are seeing, is the Limiter AMC doing its' job in the loop affecting HOW PEP will even rise, not by much, the radio is thinking it's full tilt back to the Driver and Final - this is not ALC working, it doesn't have such a feature - AMC is working before it gets to this board, nor how AMC would even care...
The Audio distortion and clipping is from the processing AFTER the Clipper diode.
You lose PEP when you run a lower carrier - the LIMITER is set for Full power, the Audio amp is only amplifying what it sees at the Mic. To work, the LIMITER needs to be modified to allow the swing and Peak to even work...AHEMN - remember we put a CAP on the Leads of JP36...
We're forgetting some key pointers...
The above, compare it, is nearly an Exact duplicate of the board, except the "compressor".
But CB Tricks did this up for their own site in early 2000's
IF you own any Sole-Battery powered vehicle Read Non Hybrid or Gas powered - in the near future - better check the Owners manual...the next key up could kill you...
Attachments
Look at the wave form on the scope after the install when testing with the 1 k tone.
If you watch closely as he keys the Mic the wave form quickly flat tops , then comes back as the limiter comes into play.
27.2059 is not what I call spot on.
73
Jeff
If you watch closely as he keys the Mic the wave form quickly flat tops , then comes back as the limiter comes into play.
27.2059 is not what I call spot on.
73
Jeff
Anyone got one yet?
Mine is still in transit.
Still need to go dig out a 29 out of the shed lol
73
Jeff
Mine is still in transit.
Still need to go dig out a 29 out of the shed lol
73
Jeff
Friend sent me this link , said this is the guy building them.
He does talk about the limiter lag.
Here
73
Jeff
He does talk about the limiter lag.
Here
73
Jeff
I got mine, but have to wait until the weekend to experiment.
Look at the wave form on the second radio an compare to the first one.
That's not the limiter lagging behind, looks like it has been defeated to me.
Why not leave the limiter intact and adjust it?
73
Jeff
That's not the limiter lagging behind, looks like it has been defeated to me.
Why not leave the limiter intact and adjust it?
73
Jeff
Yours came prescratched too!
Has anyone ever done a shootout, or remember one being done with equal antenna setups? Let’s say 5 foot Firestik. Similar year Cobra 29s. One Cobra 29 4 watts dead key set to 4:1 modulation. And the second everything set to max, swing kit, blessed by the shining golden screwdriver. Say receiving station at 5 miles and let them go to see who can do it better. I can recall the antenna tests on Coppers Forum about the old oil can antennas and open coils.
Shadetree Mechanic
Delaware Base Station 808
Hooked mine up in a new 29, will post pictures soon. The stock limiter is definitely needed, and we kinda knew that. I am using the dead key adjustment on the board with a jumper instead of an external pot. The highest dead key I can get is 2 watts. I have another new 29 with no other mods that has the Nomad board that I use for testing amps. I will compare the two to see if this new board really has an NPC like feature.
More to come.
More to come.