[AMRadio] Re: Legal limit


jeremy-ca km1h at jeremy.mv.com
Tue Nov 13 10:49:48 EST 2007


----- Original Message ----- 
From: "Ben Dover" <quixote2 at ix.netcom.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>; "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Tuesday, November 13, 2007 10:22 AM
Subject: Re: [AMRadio] Re: Legal limit


>
>
>>> 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)



I wasnt referring to any matching or power transfer.

You wouldnt catch me hooking a cap directly to the tank coil even with a so 
called safety choke. There are too many impedence and voltage variables.

Besides being a safety issue there is no harmonic suppression.

I wont even run open wire line.
All my old rigs (even the PP 211's) will be running from balanced PP output 
thru 12:1 powdered iron baluns into coax and filters. I wont even run open 
wire line. I also run 12:1 baluns/ununs on the receivers (2.5V HRO, NC-101X, 
NC-240D, SX-9, SX-28, HQ-129X, etc) from the coax feedlines and patch panel; 
it makes a big improvement.

Carl
KM1H



>
>
>
>
>>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
>
>
>
>
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