[ICOM] IC-7000 AM Modulation Problem

[msole at loxinfo.co.th]

An interesting point Peter. I'd go so far as to say dropping peak modulation depth to about 65% 
doesn't overly hurt especially if you run 6dB of compression to bring down the peak to average 
ratio so boosting the low level audio bits. Professionally I am involved with aviation comms 
which of course is all AM, well some digital as well now but that's another thing again, mostly we 
set peak mod on the transmitters to be about 80-85%, no reduction in performance ever noticed. 
We do have some 250 watt carier transmitters in service, good for 600km at times over a sea 
path.

Setting your transmitter to show 25 wats carrier and increasing the audio so it 'sounds' good is 
most likely safe and adequate for most. Amazing just how good AM can sound, even from an 
Icom!

73
Martin, HS0ZED


Quoting Peter Markavage <manualman at juno.com>:

> Actually AM'ers can run more than 375 watts of carrier output as long as
> they decrease the percentage of modulation. Running the percentage of
> modulation at 90% or 80% has little impact to the person on the receiver
> end. You generally want the AM receiver end to capture the
> signal(carrier), so under poor conditions, more carrier at the expense of
> 100% modulation, is desirable. 1500 watts PEP output is your maximum;
> carrier and modulation are your variables; adjust them according to
> conditions.
> 
> Pete, wa2cwa
> 
> On Wed, 5 Apr 2006 11:47:14 -0400 "David J. Ring, Jr." <n1ea at arrl.net>
> writes:
> > Boy, you guys are good.  25 watts carrier fully modulated at 100% 
> > does 
> > indeed produce 100 watts peak envelope power (PEP).
> > 
> > I am always amazed when I tell people that the "old standard" of 
> > having 1 kW 
> > carrier INPUT was equivalent to having 4 kW PEP input on AM phone.
> > 
> > Now AMers can only run 375 watts of carrier output - which produces 
> > 1500 
> > watts PEP output.
> > 
> > What people expect to see is 100 watts carrier fully modulated but 
> > that 
> > would be 400 watts PEP output.
> > 
> > Imagine how big the boxes would be if they were to be designed for 
> > 100 watts 
> > carrier full time to be plate modulated for 100% modulation?
> > 
> > They'd be, they'd be ... ... as big as boat anchors!
> > 
> > Of course the BA's were designed for that.
> > 
> > 73
> > 
> > David N1EA
> > ----- Original Message ----- 
> > From: "Larry Harrison" <harrisonl at comcast.net>
> > To: "ICOM Reflector" <icom at mailman.qth.net>
> > Sent: Tuesday, April 04, 2006 11:27 PM
> > Subject: Re: [ICOM] IC-7000 AM Modulation Problem
> > 
> > 
> > Adam
> > 
> > Yes this is what I thought all along.  That is why I used 25 watt 
> > carrier in
> > my original post and tests. The PEP output at 100% modulation would 
> > be 100
> > Watts. (4 X Carrier)  meeting the PA PEP rating for any 100 Watt 
> > PEP
> > transmitter.
> > 
> > Regards, 73
> > Larry K3JRR
> ----
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