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Message |
    
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 137
Registered: 12-2003
| | Posted on Friday, December 31, 2004 - 11:39 am: | 
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I got in the middle of a conversation between two guys I know wo work on radios. One guy owns a cb shop and peaks and tunes radios for $25 to $35 depending on the radio. The other guy maintains that all you have to do to a radio is clip the modulation limiter and save your money.
Is this true? what EXACTLY is done to a radio when it is peaked and tuned? What are the advantages/ disadvantages? I have a brand new Cobra 29 LTD Classic and I'm apprehensive about letting anybody put their fingers in there. |
Tech808
Moderator
Username: Tech808
Post Number: 4422
Registered: 8-2002
| | Posted on Friday, December 31, 2004 - 12:00 pm: |
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Cb,
Stay away from the guy who clips radio's.
Peak & Tune = tuning / aligning the radio for the best / maximum output and receive with out adding distortion and leaves your AMC (Automatic Modulation Control) intact.
I personally have never used or clipped a radio and refuse to work on one that has been clipped.
If the guy who does the Peak & TUne has a scope Great! if he does not have a scope look for someone who does and ask them to put it on the Scope so you can see a SMOOTH Modulation Pattern with NO Spikes in it.
It should look like SMOOTH ROLLING WAVES on the Scope when he is done.
There just is NO reason for it.
Just my nickels worth.
Lon
Tech808
CEF808
N9OSN
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Geekster
Intermediate Member
Username: Geekster
Post Number: 152
Registered: 6-2004
| | Posted on Friday, December 31, 2004 - 12:04 pm: |
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Not usually. A peak peaks max modulation without distortion, and a tune is usually an alignment for maximum receive while maintaining a low noise floor level.
The clipping isn't a good idea it can lead to distortion, TVI, and adjacent channel splatter.
Ask which communications monitor they will be using for the tune up. If they look at you funny then run for the door.
cheap tuneups aint good
good tuneups aint cheap |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Friday, December 31, 2004 - 12:58 pm: |
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The limiter is a GOOD thing so don't clip it! It works to keep the radio from overmodulating and even makes it sound louder by adding compression to the audio. That's all a limiter is - a compression circuit. For AM it's an audio compression circuit, and for SSB it's an RF compression circuit.
Geekster and Lon have it right, and I like the way that Geekster put it:
cheap tuneups aint good
good tuneups aint cheap |
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 138
Registered: 12-2003
| | Posted on Friday, December 31, 2004 - 6:33 pm: |
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Thanks everyone.
That makes alot of sense because I have heard the radios that have had the limiter clipped and they DO splatter all over the place. Most of the guys who run 1,000 + watts around here bleed all over the place, then when you say something to them about it they get all upset. |
Inspector
Intermediate Member
Username: Inspector
Post Number: 112
Registered: 12-2001
| | Posted on Friday, December 31, 2004 - 9:57 pm: |
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The parts in the radio that make up the AMC circuit are there for a reason and should not be defeated. When you defeat the AMC by clipping a part, you turn your radio into a radio like one 40 years old that never had an AMC. If you want to "sound" louder, get an amplified microphone, have the rig tuned to 100% modulation and the AMC will protect you from overmodulating. The other way is the PPE mod (the NPC with the limiter INTACT)...It gives the impression of more than 100% mod without the RFI and distortion.....Look at it this way, if Uniden, Galaxy-RCI, etc. could make their rigs louder by REMOVING parts...parts that cost them money...they would have done it long ago. They are there for a reason (and NO, the FCC did not make them do it). |
Gumball
Junior Member
Username: Gumball
Post Number: 36
Registered: 10-2004
| | Posted on Saturday, January 01, 2005 - 11:38 am: |
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Anyone who advocates removing the limiter (of "clipping the mod") has just told you that he does not know anything about radios.
And unless a tech has a scope....find another tech.
Been there, done that, sold the radio............ |
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 140
Registered: 12-2003
| | Posted on Saturday, January 01, 2005 - 12:45 pm: |
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The funniest part is that he told me he would only charge me $15 to do it because I was a friend. |
Tech808
Moderator
Username: Tech808
Post Number: 4439
Registered: 8-2002
| | Posted on Saturday, January 01, 2005 - 1:00 pm: |
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Cb,
Man with Friends like that you do not need Enemies.
Lon
Tech808
CEF808
N9OSN |
Geekster
Intermediate Member
Username: Geekster
Post Number: 154
Registered: 6-2004
| | Posted on Saturday, January 01, 2005 - 1:42 pm: |
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I would just say no thanks. If he is a friend just say no thanks and take it to a real tech. |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, January 02, 2005 - 3:54 am: |
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Wow! $15 to back out the screws, clip the leg of a transistor with a nail clipper, and put the screws back in. What does that work out to - $300/hour? Nice friend. |
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 143
Registered: 12-2003
| | Posted on Sunday, January 02, 2005 - 1:25 pm: |
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Yeah, no kidding.
He does that to everyone that comes to him with a radio. He told me that if someone comes to him with a radio that has been peaked and tuned or had a swing kit or something put in, he takes it out and clips the limiter. After that those radios sound like complete poop. The audio is distorted, you can't understand a word they say and they bleed all over the band. But I guess they think they sound good. |
Bruce
Senior Member
Username: Bruce
Post Number: 1975
Registered: 9-2003
| | Posted on Monday, January 03, 2005 - 5:06 am: |
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With all its faults the limiter does a fair job of keeping your radio narrow enough so everyone has a chance. It's not only cb'ers who need a lesson in modulation 101 there are many hams who sound like junk too........ lissin on 75 meters at night. |
