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Sparky built 100 watt cobra 25.

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  #11  
Old 10-30-2009, 03:51 AM
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Quote:
Originally Posted by W5LZ View Post
"PEP" is the only true measurement of an amplitude modulated signal" bob85"

But only if you are measuring peak envelope power. Other wise, the other means of measuring power have just as much validity. If you like 'big numbers', using Pep is sure the way to do it. If you don't know what those numbers mean, you really aren't saying anything important or significant at all. What's the difference between about 700 watts Avg/RMS, and 1000 watts Pep? Absolutely nothing.
- 'Doc

(Ask him, he'll say the same thing if he's honest about it.)

(Ask him, he'll say the same thing if he's honest about it.) I doubt that very much.Seeing as bob is well aware of what AVG power actually means and how it is measured.

There is no such thing as RMS power.

For Amplitude Modulated signals at 100% modulation:

PEP is 2.66 times AVG 100% modulated power or 4 times unmodulated carrier power.

therefore a signal of 1000w PEP would be equivalent to a 250w AVG power unmodulated carrier or a 375 watt AVG 100% modulated signal.

A huge difference between either modulated or unmodulated AVG power and your 700w AVG/RMS power.

to quote yourself:
"If you don't know what those numbers mean, you really aren't saying anything important or significant at all."
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  #12  
Old 10-30-2009, 04:34 AM
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AL (Sparky) does decent tune-up work generally included in a competative purchase price. Unlike some internet shops that would have you believing they offer several levels of peak & tune worth upwards of $40 above what the radio sells for. Anytime I have spoken to him on the phone, his answers have always been direct and honest with me. That said the Cobra 25 RFX package commands a price beyond it's value. As stated previously, aside from the increase in power, it will still be limited to the Cobra 25 features with a higher than normal current draw contained within a small unvented space, a receipt for disaster.
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Old 10-30-2009, 07:06 AM
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I think i'm going to have to just go with a 25 with out the add on amp. Someone else pointed out something i had been worried about and that is over heating,so i think I'm going to go with a 25 with mosfet final upgrade and leave it at that. Like i said the only reason i was thinking of the add on amp + the cobra 25 was because there does not seem to be any other place to mount a full size radio such as a 95T

Also thought about maybe the Magnum 257 but i cant find any info on the net about the over all size of the compared compared to a 25. Do any of you know if they are close in size?
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Old 10-30-2009, 07:15 AM
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257 would be a great choice....

25 dimensions
6-1/4 x 2-1/8 x 8-5/8


257 dimensions
Length: 9 1/2 " approx.
Width: 6 "
Height: 2 "


pretty damn close, and a helluva lot more radio....
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Old 10-30-2009, 08:43 AM
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Quote:
Originally Posted by W5LZ View Post
"PEP" is the only true measurement of an amplitude modulated signal" bob85"

But only if you are measuring peak envelope power. Other wise, the other means of measuring power have just as much validity. If you like 'big numbers', using Pep is sure the way to do it. If you don't know what those numbers mean, you really aren't saying anything important or significant at all. What's the difference between about 700 watts Avg/RMS, and 1000 watts Pep? Absolutely nothing.
- 'Doc

(Ask him, he'll say the same thing if he's honest about it.)
1000 watts PEP is roughly 700 watts average if you calculate 1 and 1/2 times the resting carrier then you'll have the same figures which would show approximate modulation.
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Old 10-30-2009, 08:45 AM
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Quote:
Originally Posted by jazzsinger View Post
(Ask him, he'll say the same thing if he's honest about it.) I doubt that very much.Seeing as bob is well aware of what AVG power actually means and how it is measured.

There is no such thing as RMS power.

For Amplitude Modulated signals at 100% modulation:

PEP is 2.66 times AVG 100% modulated power or 4 times unmodulated carrier power.

therefore a signal of 1000w PEP would be equivalent to a 250w AVG power unmodulated carrier or a 375 watt AVG 100% modulated signal.

A huge difference between either modulated or unmodulated AVG power and your 700w AVG/RMS power.

to quote yourself:
"If you don't know what those numbers mean, you really aren't saying anything important or significant at all."
Oh snap! that's a big gator.
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Last edited by mackmobile43; 10-30-2009 at 09:10 AM.
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Old 10-30-2009, 09:08 AM
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your better off buying a radio thats factory made to do this wattage RCI 2970 GALAXY 95T these types of radios are true power and your getting so much more ontop of the power like SSB FM and all the band coverage which nobody had to nip n tuck clip and cut to get.
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Old 10-30-2009, 10:35 AM
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"Oh snap! that's a big gator."

Yes it is, isn't it? I think I should be able to get at least one pair of shoes and maybe a hand bag out of that one. Too bad I don't need a pair of shoes. The hand bag does sound nice though. I'd suggest that you read exactly what I said, and not any more than what I said, when you make assumptions about what you think i said. Enough said?
- 'Doc

Assuming there are any 'gators' in the UK, other than the zoo?
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Old 10-30-2009, 12:25 PM
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Quote:
Originally Posted by 1515 View Post
Actually PEP is the true, correct way to measure it
That's why there's not an avg. reading meter on a cb radio and that's because the guys who make them don't gain any knowledge from reading these forums.
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