rest of Cobra 148F thread

[ken white]

...However, I see where I misread and lumped in the formulas for calculating modulation percentage with the text on nominal power. Here the source that messed me up: (Scroll down to the definition of modulation percentage, you'll see where I mistook that for part of the paragraph for Nominal Power)

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div6&view=text&node=47:4.0.1.1.2.1&idno=47

I still wish people would get away from the term "RMS Power", when they really mean "Average Power". RMS is a measurement of voltage, not wattage. I know, the term is meant to say that the RMS method of calculating voltage is used to determine power levels, but it's still confusing to the casual reader.

It seems to me the FCC has been trying to get away from Average power measurements (at least for the Amateur world)? All the Amatuer requirements are stated in terms of PEP now. All my equipment that has built in meters (tuners, amps, etc.) all have active peak reading meters. My Bird has the peak kit...I really only have one meter that doesn't have an active peak reading circuit anymore...

If you look at my other post you will see that the modulation index can be used for calculating PEP and RMS/Average Power to show how they are related. However, PEP can be calculated directly from the modulated envelope if the RMS/Average Power is not desired.

As for the RMS comments, Average Power can only be calculated using RMS Current and/or Voltage so I don't think the RMS terminology will go away. Any calculation of power that does not use RMS values will be wrong.

You need to look at why RMS values were developed to appreciate this metrics value.

Energy is the primary metric that "All" engineering diciplines share and the SI unit is the "joule". Power is defined as the change in energy per a change in time, which means a change in joules per second (J/s). So the units of energy must be consistant between "All" engineering fields.

RMS is defined as an "effective" value of voltage or current that produces the same energy transfer (watts) for time varying signals that a defined DC source will. So, RMS values are the only values that exactly describe wattage or energy transfer in joules. Average Power is calculated over one cycle by multiplying the RMS Voltage x RMS Current x Cos (phase angle between the voltage and current). So, RMS and Average can be thought of as one and the same.

As for peak meters, they are cheap, easy to build, and are fairly accurate so that is why they are popular in the amateur market. Notice that PEP and RMS power are directly related so that is why the FCC may use this terminology, not because RMS power doessn't exist...

 

[Happy_Hamer]

Well I think if you want to save money just buy a radio shack watt meter and cut your CB antenna 1 inch at a time until you see the maximum wattage, i think you will be happy.

Results may vary, do at your own risk. I am not a professional

Just wanted to make sure my cheap peak and tune procedure made it to page 2

Thank you

 

[Moleculo]

Ken...I follow you and appreciate the detailed explanations...it helps clear things up in my brain, at least.

 

[Slim]

Well I think if you want to save money just buy a radio shack watt meter and cut your CB antenna 1 inch at a time until you see the maximum wattage, i think you will be happy.
Very,Very cute there Hamer!!!!!! BUT so true
Results may vary, do at your own risk. I am not a professional

Very,Very cute there Hamer!!!!!! BUT so true

 

[Switch Kit]

Ken...I follow you and appreciate the detailed explanations...it helps clear things up in my brain, at least.

Like I said Mole , some care more then others do . for some , it can simply be Much Ado about nothing. Like anything over 100% modualtion / NPC mods / Swing Kits / clipped diodes / dirty amps / clean amps / this way and that way /whom does what to whom and whos says it's OK or not/ ect. ect. ect. Around here so very often , if someone DOESN'T have a problem with any of the above , they tend to be less then human, which I find far from the truth. In the beginning I kind of thought the thread to be more so a feedback kind of thread then anything else , but I guess Nightrider was just tickled pink so he decided to praise you this way and then Pyscho kind of added his feelings and it went from there. It's all good

 

[nightrider]

ok somebody send me a bird43p and i will shoot and host a video clip of the 148fgtl on 14.6 volts, pep and rms ???????
now yes i am pleased switch kit, radio talks very well but if you wanna break it right down it talks and does so very well at that, all that matters to me .............

 

[Butcher318]

Sounds like you got a very complete tune no doubt, bet it sounds great.

 

[davegrantsr]

butcher may be the 'resident complainer', but, i as well detest that 'As general occurance people always seem to quote unrealistic wattage numbers from their radio's. I wish people would get real on that stuff.' i can honestly say NOBODY has EVER brought me a radio that even got within a few watts of what whichever world famous tech tuned it to. yup, many of the 'tuned' radios that allegedly were getting 25-35-55-75 watts or WHATEVER were LUCKY to see 75% of that number on a wm1, sx100, 43/43p or whatever professional reader was available at the time of 'testing'. the argument isn't the TYPE of mod used to make the watts, cleanliness or clarity of the signal, but the blatant over-exaggeration of output numbers. i have had more then my share of grant xl users absolutely DROOL over the signal reports they got-or how the radio sounded to them. the disappointment in their EYES was almost SCARY when they saw 17 or 18 watts on the 43p, & it was worse when they saw 12 on the 43. THEN they would hear a 'local-tech' tuned XL at 25 or 30 or 923 (single '69 watts ) & realize that THEIR number, lower though it may be, sounds overwhelmingly better & gets NO COMPLAINTS. they feel EVEN BETTER when they receive COMPLIMENTS on their radio at ONLY 16 watts & the 'listener's' radio at supposedly double the power is nearly unintelligable. EVERY SINGLE CBer that requests or owns a 50+ watt cobra 29 should be beaten til he's happy to see it sounding good doing 15 watts. i have NO PROBLEMS claiming the 16 watts out of my radio. it has vaporized more then a few alleging double the output. same as when i race. yeah, i only got 275 horses....you want me to give you a car-length headstart? i'm SURE your 500 horse naturally aspirated on 87 octane 5.0 is gonna NEED at least that much if you wanna be in front of me at all during the race....

 

[Happy_Hamer]

This one time,,,,,,at band camp

 

[Happy_Hamer]

Can I ask a question here? Nightrider was only saying he liked the radio and was happy with the results.

Why do we really care how many watts he claims the radio was putting out?

1. HE IS HAPPY WITH HIS RADIO
2. HE IS HAPPY WITH HIS RADIO
3. I THINK HE IS HAPPY WITH HIS RADIO
4. SEE NUMBER 1.

Now I am going to get on the radio and look for some DX, I got a Uniden Grant LT, STOCK, and it puts out 25 watts on AM and 75 on SSB.

I use a fliputheBIRD 43PEE disambiguation watt meter!

 

[davegrantsr]

i'm happy for him, then. of course, i STILL don't believe it

 

[Happy_Hamer]

i'm happy for him, then. of course, i STILL don't believe it

What about Santa clause?

Have fun and enjoy the forum

 

[davegrantsr]

i LOVE santa :rknrl .....he brought me my 1st 11 watt grant XL when i was but just a kid. i took my tinker toy screwdriver & little tikes plastic hammer to it, got 18 watts out of it & have been in love with mb8719 SSB radios ever since. mom told me i got such a good christmas present because i didn't lie about output wattage :naughty .

 

[Moleculo]

i'm happy for him, then. of course, i STILL don't believe it

Then you are calling me a liar without any first hand experience or knowledge of what I did to the radio as a basis for that accusation. It's OK though, I don't get offended easily. Believe whatever you want to believe...it's a free country. But please don't start throwing accusations around about me lieing when I've never done any work on a radio for you to warrant those accusations.

 

[skirtchaser]

My mom says it's not good to tell other people what to do cause' they can do whatever they want. Want some of my Ice Cream....it's staw burry!