Thanks John, I probably should have been a bit clearer, I would like to get at least 600W out PEP.
I checked today and the power supply is running 2812 VDC unloaded. I am starting to question my results yesterday as I have been told I probably did not tune the amp correctly. That is what I get for being a new guy I guess... Bow W5EFR -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Monday, April 23, 2007 10:04 To: 'Discussion of AM Radio in the Amateur Service' Subject: RE: [AMRadio] My Amplifer Quest took a strange turn today Bow: You need to start over if you want to get 600 watts carrier output. A pair of 813s is just not capable of doing this in linear AM service. 150 to 200 watts is about it. And you don't have enough power supply either for large AM service. Keep in mind that to get a carrier of 600 watts on AM you must have an amplifier capable of over 2400 watts (4 X carrier). Even so there is another draw back in that when a linier amplifier is operated at full drive and full output (lets say 2500 watts) its efficiency is 60-75 percent and with no input its efficiency is Zero percent. With this in mind you can figure that at 25% of the full drive power and output, that the efficiency will be between 0 and 70 percent and in most cases it is around 25-30 percent. This means that the amp can produce a lot more heat when driven at 25% of full output than it does at full output. Hence the probability of damage to light weight part is great. There are some rules of thumb to be used for linear amplifiers in AM service, and these rules are a lot different in requirements for big equipment than the rules of thumb for SSB service. This is the reason that many times it is better to use class C plate modulated service instead. You have some parts there that could be very usefull and the 813s or capable of all you want and more, in class C service I would be happy to help with some graphs and drawing to get you started if you want to come by for so coffee. The Computer Fixer 1622 Sawdust Rd. Ste A1 The Woodlands, TX 77380 281-367-6765 PS: bring Chocolate Chip cookies -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bow Sent: Monday, April 23, 2007 2:39 AM To: 'Discussion of AM Radio in the Amateur Service'; Glowbugs Subject: RE: [AMRadio] My Amplifer Quest took a strange turn today Well, A bit of an update on my new toy.. I tested it today, after repairing some solder joints that were not up to my specs and replacing some wire I didn't like that looks of. The test was: Icom IC-718 --> MFJ-949E antenna tuner-->Amplifier-->Daiwa 3kw watt meter-->MFJ legal limit dummy load. The IC-718 will do 100 Watts on CW/SSB/Rtty and 40 watts on AM I used the frequency of 3870 kHz I first used a RTTY signal Input from Rig - Output from Amp - Grid Current (amps) - Plate Current (amps) 30 - 180 - .02 - .24 50 - 380 - .07 - .34 60 - 400 - 0.1 - .36 75 - 410 - 0.2 - 0.4 Next I tried an unmodulated AM carrier 25 - 200 - .04 - .26 40 - 375 - 0.1 - .34 Final Check was on SSB, modulated to the peak ALC setting with a 1 kHz tone. 30 - 110 - .02 - .16 40 - 200 - .02 - .18 50 - 210 - .02 - .22 60 - 300 - .04 - .22 70 - 375 - .04 - .24 80 - 400 - .06 - .26 I figured 80 watts was about as hard as I want to drive it. I don't have a High Voltage test lead here to actually check the plate voltage, but I am going to take this featherweight (NOT!!!) into work with me and check it out there. Here are some more photos, including the guts. I may just rewire this thing for my own piece of mind. http://riley-music.com/BowsStuff/AMP/14Guts.JPG http://riley-music.com/BowsStuff/AMP/15TubeSockets.JPG http://riley-music.com/BowsStuff/AMP/16Relay.JPG http://riley-music.com/BowsStuff/AMP/17PWRSection.JPG http://riley-music.com/BowsStuff/AMP/18MeterSwitch.JPG http://riley-music.com/BowsStuff/AMP/19CapChoke.JPG http://riley-music.com/BowsStuff/AMP/20FilTranny.JPG http://riley-music.com/BowsStuff/AMP/21PWRTranny.JPG http://riley-music.com/BowsStuff/AMP/22CoilSwch.JPG I guess now I need to figure out how to do a few things.... Get an opinion from someone who knows something about amplifiers and homebrewing.... 1. Make it band switch able for 80/40/20/10 2. Figure out a tuned input for the above bands 3. figure out how to get it up to a 600 watt output level (because everyone tells me the first 600 watts are the best for signal boost) Bow W5EFR -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 269.5.7/771 - Release Date: 4/21/2007 11:56 ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body. ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body. No virus found in this incoming message. Checked by AVG Free Edition. 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