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PEP? Are Those Power Meters Showing Us PEP Peak Envelope Power, or just Peak Power?

Discussion in 'Amateur Radio Amplifiers' started by KQ4X, Dec 31, 2012.

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  1. WA4AXT

    WA4AXT Ham Member QRZ Page

    When say Peak Envelope Power , PEP or peak power , your talking about the same reading just expressed in different way . Its simply the maximum power or the measurement of the crest of the wave . If you want a cheap meter that reads PEP and does a good job then just go on line and purchase a used Heathkit HD-2140 like I have which reads both peak and average power at the push of a button .

    [​IMG]

    I know now its not your fault , but the thought of a person holding a extra class license and operating a legal limit amp who does not fully understand something as fundamental as average , rms and peak power is not a good sign . Its like a comment a guy made on a Kenwood boat anchor site I read in recent times who damaged the finals on his transmitter and wondered why the manufacture did not post a warning that such a thing could happen if the unit is not tuned up properly .At the time the radio was being sold in the early 1980es , it was not unreasonable for Kenwood to assume that a licensed operator would know that fact but today ? I think the FCC should at the very least bring back the requirement that each person hold each class of license starting with the lowest class for at least a year before being eligible to take a advancement test to acquire a higher class of license .
     
    Last edited: Dec 31, 2012
  2. K7JEM

    K7JEM Ham Member QRZ Page

    This is true. But you can do your taxes without a calculator or an accountant. The tax tables are provided in the form.

    The point is that we are not told how to comply with the rule, just that we have to do it. Your post made it sound as if someone had to own a wattmeter if they were going to operate at or near the legal limit.

    If you have a wattmeter that indicates 1400 watts out, yet you are really doing 1600 watts out, you are not complying with the rule. If you have no wattmeter, but regardless, are staying below 1500 watts, you are complying with the rule. The FCC doesn't care how you comply with the rule, just that you do it.

    Joe
     
  3. K7JEM

    K7JEM Ham Member QRZ Page

    I think you need to read your original post about this and see if you can figure out why I posted what I did. You may or may not be able to see that what you posted implied that the FCC requires you to have a wattmeter. They do not. Having a wattmeter doesn't mean you will comply, since your wattmeter may not be accurate, and even if it is, you can still ignore it.

    If you read the rules you will see that the max power rules don't even talk about wattmeters, they just set limits. How you comply with those limits is your responsibility.

    Having a wattmeter is a good idea, but it's not required by the FCC rules.

    Joe
     
  4. KV6O

    KV6O Ham Member QRZ Page

    Huh? I thought the point he made was logical and not argumentative at all. How you comply is up to you - that was his point.

    If I am running QRP off a battery at a campsite, I will be in compliance of the max power rules without a power meter. When I use my 2 Meter HT, I don't have a power meter inline. There are lots of examples of not needing to measure your power and still be in compliance. Many, if not most hams will never need to worry about this. Notable exceptions are when running an amplifier (obviously) and on bands with power restrictions that make it prudent to monitor.




     
  5. W1BR

    W1BR Premium Subscriber QRZ Page

    Many inexpensive "peak reading" wattmeters use a cheap, passive circuit that is nothing more than an electrolytic cap to "hold" the peak reading. I've never seen one that was accurate. As others noted, the best method is to use a monitor scope. Set the power for 1.5kW CW output, and make a note of the vertical deflection, and then keep the SSB peaks at or below those points. Besides, the scope will show flat-topping and other issues that are just as important.

    Pete
     
    Last edited: Dec 31, 2012
  6. AA5CT

    AA5CT Ham Member QRZ Page

    ... scope.

    ?
     
  7. AA5CT

    AA5CT Ham Member QRZ Page

    It's those pesky "multiply Line 17 x .0137 and enter that number on Line 18" that beg for a calculator ...
     
  8. AA5CT

    AA5CT Ham Member QRZ Page

    We (hams, in general) should have grown wise to these 'ploys' when rigs in the 50's were called/named: "Globe King" and the like! :D

    (It's not like the hype started yesterday is my point.)

    Jim
     
  9. WA4AXT

    WA4AXT Ham Member QRZ Page

    The Heathkit HM-2140 uses 4 op amp stages and can be purchased on E-BAY right now for about $40 . Its not as good as a scope but good enough for Ham operation . I mean what ham routinely has his test equipment sent to a calibration lab to be certified as accurate like is required when working on some commercial or military equipment ? http://www.ebay.com/itm/HEATHKIT-MO...6?pt=US_Radio_Comm_Meters&hash=item484e66fa72
     
  10. W1BR

    W1BR Premium Subscriber QRZ Page

    I agree.... but something like a Diamond SX-200 simply switches in an electrolytic cap to go from average to peak power. It isn't very accurate. Heck, I may throw a bit on that wattmeter :)

    Most in line meters are accurate if the load is a pure 50 ohm resistive load.

    I doubt the FCC is going to issue a violation unless the ham is in obviously trying to circumvent the rules..

    Pete
     
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