[AMRadio] Re: Legal limit


Ben Dover quixote2 at ix.netcom.com
Tue Nov 13 10:22:09 EST 2007



>> Most likely, they wouldn't have any way to measure anything that is not 
>> fed by 50-ohm coax.  What if you use link coupling directly to a tuner 
>> that feeds open wire line, with only a pair of wires to tie the two links 
>> together?  Or if you feed the open wire line directly from a pick-up coil 
>> coupled directly to the tank?
>
>
>Its called a balun, and prepackaged ones of many ratios are readily 
>available. Clip, clip and measure into the Bird.
>
>
>
>Or what about an antenna that is connected
>> directly to the tank circuit without any feedline or tuner?
>
>
>Now, that is definitely asking for trouble. I'd hope that no one does that 
>method any longer.


On the contrary...  oddball line impedances and single wire feeders are the
easiest of all to deal with.

If you run such a setup, you DO have an RF ammeter in the line for tuneup,
do you not? And before putting that new antenna into service, you went over
it with an RF impedance bridge, didn't ya?  ;o)  

Once you mathmatically deal with the reactance, your RMS power is simply a
matter of I squared times R. From that you can come up with feedpoint voltage
figures for an unmodulated carrier, and using a simple capacitive voltage 
divider at that point, attach a scope to determine the voltage difference
between resting carrier and 100% modulation.

By that time you have all the information you need to calculate your PEP.

It's not as simple as sticking a Bird peak reader into a 50 ohm line, but
it's not THAT difficult if you know what you're doing. And I guarantee you
the PEP figure you come up with will be far more accurate than a Bird will
EVER give ya!   :o)




>Bottom line is that Charlie is no more interested in an AMer that is a few 
>dB over the limit than they are with anyone else running an 8877, 2 x 
>3CX800, or similar amp on SSB or CW that can easily crank out 2500W.
>What gets Charlies attention is the obvious troublemaker or braggart that 
>thinks its cool to talk about his two 4-1000A's, 4CX5000, etc, meanwhile 
>being 20 KHz wide.


AMEN to that! Exactly the point I was trying to make. The Friendly Cookie 
Company is too busy cutting big deals to give a damn about what happens on
the ham bands. The only time you have to sweat them is if there's an obvious
and major problem...  like K1MAN found out!  ;o)

It's been a lot of years, but I HAVE experienced an FCC inspection (some TVI
complaints back in Chicago). My experience with it wasn't that bad.

As a broadcaster, the FCC is always in my mind, tho even professionally
the encounters with The Feds are rare...  and always nonconfrontational.

FCC field engineers aren't geniuses, nor are they dummies... they're just guys
who are working for a living. They're not out to slap you in the head if they
can. In fact, most of them are/were HAMS, just like you.

If you can give them explainations and justifications that are based on solid
engineering principles, and YOU DON'T TRY TO BS 'EM, most perceived problems
can be resolved. In fact, even if you aren't experienced or skilled enough to
deal with a technical problem yourself, some of these guys will go out of thier
way to help you; one Chicago office engineer is a lifelong FRIEND of mine. He
became Elmer (I hate that term! <<smile>>) to a lot of guys... some of whom he
met when he D/Fed and busted 'em as bootlegging high school kids!

In general... about the only time these guys go into a full blown Judah Mansbach
mode is when you try to be a wise guy, and pull violations that are DELIBERATE
and FLAGRANT.



>Im sure we all know at least one SSB op that is running 5KW+ but has never 
>been bothered. I'd have to take off my shoes and socks to be able to add up 
>the ones I know of.

Exactly. The key to Peaceful Piracy on the ham bands is to NOT act like a jerk
on the air. Just because you've got 10 KW, you DON'T have to use it to push 
everyone else around on the air. If you just apply the Golden Rule, even HUGE
power violations are unlikely to result in a knock on the door from a Fed.



Mr. T., W9LBB






More information about the AMRadio mailing list

This page last updated 23 Oct 2017.