Yes, those numbers are possible in amateur service. When I ran a pair of 3-400s linear, I ran about 800 watts carrier input, I got about 160 watts carrier output, disspipation about 640 watts, 200 % mod, and about 1500 PEP out. (Efficiency gets bad when you set them up that way.)
If I turned the audio down to about 100%, I could raise the carrier level and get 350 watts carrier output, carrier input about 1100 watts, PEP about 1500 watts, dissipation about 750 watts. The tubes did get hot that way, though. Bacon, WA3WDR ----- Original Message ----- From: "Jim candela" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" <[email protected]> Sent: Thursday, March 16, 2006 7:22 PM Subject: RE: [AMRadio] Amplifier to use with my DX-60 > > Don, > > You said: "So you could run maximum 1500 watts DC input to those tubes, > with 500 watts > carrier output, and 1000 watts dissipated by the tubes". > > Reply from Jim WD5JKO: > > What is stated above is correct if the tubes can dissipate 1000 watts of > heat (like two 3-500Z's flat out blushing), and the drive is adjusted to > about 1/4th that for maximum PEP output. In this case the efficiency is > assummed to be about 33%, so 1500 X .333 = 500 watts. The efficiency may > vary some, and is usually lower then that, so the 33% assumption is only a > first guess. It could be 25%, and that really upsets the situation making > the linear more of a heater, and less of a transmitter. > > One good thing about the 1500 watt PEP output power rule we all complain > about is that efficiency doesn't matter as much now. You can legally run a > 15 KW PEP input amplifier with 10% efficiency to provide 1500 watts PEP > output. It wouldn't make a lot of sense, or be practical, but it's now > legal. Back in the 1000 watts DC input days things were a lot different, and > the SB-220's input would likely exceed 1000 watts DC before the AM carrier > got to 375 like we often do today with these amps. The point here is that > for low efficiency linears, or grid modulated amplifiers, we can sometimes > run more power today on AM then before the rules changed from 1000 watts DC > input to 1500 watts PEP output. Of course this isn't the case with plate > modulation where an output PEP at or maybe more than 3KW PEP WAS possible, > and completely legal. > > Regards, > Jim > WD5JKO > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of kenw2dtc > Sent: Thursday, March 16, 2006 4:21 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Amplifier to use with my DX-60 > > > Don says: > > "So you could run maximum 1500 watts DC input to those tubes, with 500 watts > carrier output, and 1000 watts dissipated by the tubes" > > *******I need a little help with the math here Don. You are suggesting that > with a class B linear in AM mode, one can get 2000 watts PEP with 1500 watts > input ? > > 73, > Ken W2DTC > > _______________________________________________________ _______ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 > > _______________________________________________________ _______ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb >
