[AMPS] PEP philosophy/rules

[measures]

>
>
>Hi All,
>
>If I may, I'd like to start a "philosophical" thread which arises from: 
>i)  many of us home-brewing amps
>ii) tuning with a string of high-speed (i.e. high-speed
>    compared to the time constants of our meters) vs. 
>    key-down, vs. whistling or saying "hoooooooola" into
>    the microphone.
>iii) our desire to remain legal.
>
€   FCC inspectors allow 10% for error, so the actual limit is 1650w.  
However, I know of instances where the 1650w figure was slightly exceeded 
without raising inspectors' eyebrows.  The bottom-line is that even 
1db/26% makes virtually no difference on the air, so who really cares?  
FCC inspectors are more likely to be after sources of interference than 
gnats.  .  

>Here's the situation:  (non-US hams, please fill in the appropriate 
>numbers)
>
>Suppose I tune my home-brew amp to put out the US allowed 
>maximum of 1500W under key-down conditions.  My HV drops from say 
>3200V (key up) to 3000V (key down). Now if I send CW, my HV doesn't 
>drop quite as far, so I'm probably putting out more power, say 1600W 
>for the sake of the example.  If I transmit SSB, the HV dops even 
>less, and I'll actually be putting out maybe 1700W PEP.
>
>Now if I'm able to monitor my output signal with a good oscilloscope, 
>(and my antenna represents a pure resistive load whose value I know 
>accurately, but let's not go there right now) then I can just turn 
>down my drive a bit, and stay legal.  The burden of staying below 
>1500W PEP output power is on me, the designer, builder, 
>owner-operator of the amp.  But suppose I don't have a sure-fire, lab 
>quality means of measuring my true PEP under all conditions (FM, CW, 
>SSB, AM etc.)  How can I be sure I get maximum output and still 
>comply?  Well, I can tune with a string of fast dits.  But the 
>problem (of exceeding 1500W PEP) still remains; it's just different 
>in magnitude.
>
>But wait!  It doesn't have to be a HB amp!  What if I own one of many 
>1500W output commercially available, type-approved, amplifiers?  I 
>still have the same problem(s)!  How does, say, Alpha Power, (to take 
>a high-quality example) make sure that no more than 1500W goes out?  
>Did they have to do that to get US FCC type acceptance?  How much 
>"overhead," i.e. how much more than 1500W PEP does the FCC consider 
>compliant?  Are high speed dits satisfactory?  Do the manuals include 
>this as a tuning method? Should they?  
>
>These questions came to me in an RF-induced dream after a recent 
>contest.  Maybe I should post this to an FCC part97 reflector! 8>)
>All responses are welcome!
>
>73,
>
>George T. Daughters, K6GT
>
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>


-  Rich..., 805.386.3734, www.vcnet.com/measures.  


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