Re: [AMRadio] power ratings
From: Mike Dorworth,K4XM [EMAIL PROTECTED] The total power pulled from power supply determines effeciency. A low level and linear consumes less power for same carrier power. See some KW mobile rigs from years ago. also I remember WCKY had 500,000 watts modulated carrier ( 2 megawatts pep) and it was from a LINEAR!... I never heard of WCKY running super power. WLW ran something like that just before WW2. They used plate modulation, not linear. Most of that transmitter is still at the transmitter site - the stuff is too big and heavy to move out without demolishing the building. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] power ratings
Donald Chester wrote: Gary K4FMX said: The best quality audio of all can be gotten from low level modulation and a linear amplifier. A linear amplifier has the same kind of distortion as a class-B modulator. That's true except with a linear amp most of the distortion products fall outside the audio bandwidth. 2nd and third harmonics etc. are outside the audio bandwidth. With tubes, the best quality audio can be had from low distortion plate modulators such as class-A series or Heising modulation, or pushpull plate modulators running class A or AB1. Except for the distortion introduced by the modulation transformer. Pulse-width series modulators produce perhaps the best audio. I suspect the best quality of all comes from the new class-E rigs. Agreed. According to the tube manuals, class-B audio service has inherent distortion levels on the order of 3-5%. It can be reduced with negative feedback. My Gates BC1-T manual claims less than 2% distortion at 100% modulation. The signal driving a linear amplifier has its own distortion, since the original signal has to be produced somehow. Pushpull class-A audio or series modulation, with feedback, might be a good candidate for the driver stage of a linear. If the linear is run properly in class AB1, that would be near the best possible audio out of a tube transmitter, even though the efficiency is not all that good. With low level modulation and a linear amp it is much easier to produce excellent audio than it is from high level plate modulation. Building a low power (driver) low distortion AM transmitter has fewer problems than high power low distortion transmitters. Class A direct coupled modulation schemes can be accomplished much easier at low levels than at high levels. Use of a balanced modulator can also eliminate the problems associated with occasional over modulation that plagues high level conventional modulation. Speaking of efficiency, an AM linear or grid modulated amplifier has close to the same overall efficiency as plate modulation, when calculated from the ratio of power drawn from the a.c. mains, to rf carrier output. A linear amplifier running AM has exactly the same efficiency as when it runs SSB. It's just that the duty cycle is different. That's true. An SSB amplifier at a power output level of 1/4 its full power has an efficiency level of exactly 50% of its full power out efficiency. If it is 66% efficient at full output it will be 33% efficient at 1/4 power output level. Just like it is with an AM signal as you say. Actually, since with the human voice, the average power is 7-8 dB lower than peak power (equivalent to around 30% modulation), the average efficiency of a SSB linear is similar to that of an AM linear because the efficiency of a linear is a function of the amplitude of the signal (0% at idling current, and a maximum of about 67% at maximum peak output just below the point of saturation or flat-topping). AM linears got their reputation as low efficiency on AM because of the 100% duty cycle carrier runs about 30% efficiency to allow enough headroom for the positive peaks. With an AM linear, you can see the glow on the plates DECREASE when you whistle into the mic to produce 100% tone modulation. The DC input is the same regardless of modulation, but the rf output is higher, since sideband energy is now included. That power has to come from somewhere, so the efficiency of the amplifier goes up to generate the sidebands. The advantage of plate modulation with AM is the ease of tuning up and QSY'ing. You simply dip the final and load to the desired carrier output, while maintaining enough grid drive to assure class-C service. With low-level modulation (linear or grid modulated), the rf drive level and degree of antenna coupling are critical to the modulation linearity of the final. With a rice box type exciter and amp for low level modulation all one has to do is turn the knob to insert full drive, tune both final and load controls for maximum output and then reduce drive to 25% of full output and you are good to go. 73 Gary K4FMX
Re: [AMRadio] power ratings
[EMAIL PROTECTED] wrote: I have a junker HW-100 with a good PA section. How much power could I run as a linear amp using 2X6146 and what rating power supply would I need? Thanks. Ed K6UUZ 25 watts carrier with 100 watts pep output on the 6146's. 73 Gary K4FMX
Re: [AMRadio] power ratings
Thanks, Gary. Ed K6UUZ On Mon, 11 Jul 2005 22:58:26 -0400 Gary Schafer [EMAIL PROTECTED] writes: [EMAIL PROTECTED] wrote: I have a junker HW-100 with a good PA section. How much power could I run as a linear amp using 2X6146 and what rating power supply would I need? Thanks. Ed K6UUZ 25 watts carrier with 100 watts pep output on the 6146's. 73 Gary K4FMX __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
[EMAIL PROTECTED] wrote: Thanks, Gary. Ed K6UUZ On Mon, 11 Jul 2005 22:58:26 -0400 Gary Schafer [EMAIL PROTECTED] writes: because of the class of service. read here (http://www.qsl.net/wa5bxo/asyam/aam3.html) for a good explanation of everything related. 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
The plate dissapation of the 6146's is the key. Your carrier steady on should not exceed the dissapation rating. This is about 50 watts if I remember right which would give you 200 watts PEP. So your power suppl;y should be capable of about 150 watts continuous and it will handle the 200 watts on peaks. I would beef up the fan so that I had a good amount of air passing the glass of the 6146's to keep the seals cool. There were several articles in old mags for the conversion of DX100 to linears for the SB10. Those would be a good start for info. Healthfully yours, DON W4BWS - Original Message - From: [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Monday, July 11, 2005 8:32 PM Subject: [AMRadio] power ratings I want to thank everyone who responded to my question. The consensus of opinion is that the AL-811 runs 100 watts of carrier on AM with 400 watts PEP. This with 3X811 while my DX-100 does the same thing with 2X6146. Doesn't sound right, does it? I have a junker HW-100 with a good PA section. How much power could I run as a linear amp using 2X6146 and what rating power supply would I need? Thanks. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
Ye3s but the cost of a good modulation transformer for 300 watts or more would be as much as a SB200. Actually for a good rig you could run a pair of 813 or a high power triode similar tube at about 800 watts and cathode modulate at 400 watts. This is cost effective and works well. Tetrode tubes do not cathode modulate well. Healthfully yours, DON W4BWS - Original Message - From: Byron Lichtenwalner [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Monday, July 11, 2005 8:54 PM Subject: Re: [AMRadio] power ratings Ed Shows you what high level modulation can do, with finals running in Class C vs. the amp running in linear mode. Byron, W3WKR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
Rev. Don Sanders wrote: Ye3s but the cost of a good modulation transformer for 300 watts or more would be as much as a SB200. Actually for a good rig you could run a pair of 813 or a high power triode similar tube at about 800 watts and cathode modulate at 400 watts. This is cost effective and works well. Tetrode tubes do not cathode modulate well. Healthfully yours, Anyone looking to buy some 450TL's? 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
The plate dissipation of the 6146's is the key. Your carrier steady on should not exceed the dissipation rating. This is about 50 watts if I remember right which would give you 200 watts PEP. So your power suppl;y should be capable of about 150 watts continuous and it will handle the 200 watts on peaks. I would beef up the fan so that I had a good amount of air passing the glass of the 6146's to keep the seals cool. In AM linear service, the carrier output should not exceed HALF the total plate dissipation. A 6146 runs about 25 watts plate dissipation, so with a pair of them, you should be able to run 25 watts out. With 100% modulation in the positive direction, that would be 100 watts pep. A properly functioning AM final capable of 100% modulation should run about 33% carrier efficiency. That means that two-thirds of the input power is dissipated in the plates of the final, and one third is delivered as rf output. When the carrier is modulated, the final actually becomes more efficient, so the plate dissipation is reduced under modulated conditions. The DC input should not vary, so that simply means that some of the DC input that was being dissipated as heat is now being converted to rf output in the form of sideband power.
Re: [AMRadio] power ratings
Donald Chester wrote: The plate dissipation of the 6146's is the key. Your carrier steady on should not exceed the dissipation rating. This is about 50 watts if I remember right which would give you 200 watts PEP. So your power suppl;y should be capable of about 150 watts continuous and it will handle the 200 watts on peaks. I would beef up the fan so that I had a good amount of air passing the glass of the 6146's to keep the seals cool. In AM linear service, the carrier output should not exceed HALF the total plate dissipation. A 6146 runs about 25 watts plate dissipation, so with a pair of them, you should be able to run 25 watts out. With 100% modulation in the positive direction, that would be 100 watts pep. A properly functioning AM final capable of 100% modulation should run about 33% carrier efficiency. That means that two-thirds of the input power is dissipated in the plates of the final, and one third is delivered as rf output. When the carrier is modulated, the final actually becomes more efficient, so the plate dissipation is reduced under modulated conditions. The DC input should not vary, so that simply means that some of the DC input that was being dissipated as heat is now being converted to rf output in the form of sideband power. Is that where sideband energy then is created and therefore exists as long as there's a modulate AM carrier? I wasn't in on the big discussion about this, a few months ago. --- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
Ken, as I read the rules, we are only allowed to run 375 watts carrier. With 100% modulation this will give us 1500 watts pep which is the max output allowed. I agree 300 watts carrier is almost necessary, however smaller linears wont handle that and if funds are limited, 150 watts with 600 pep isw better than nothing. I use my DX60B into the SB200 and the controlled carrier helps to keep the plate dissapation low on the 572B's. Healthfully yours, DON W4BWS - Original Message - From: kenw2dtc [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Tuesday, July 12, 2005 2:39 PM Subject: Re: [AMRadio] power ratings I've been using linear amps in AM service for a few year now. With current band conditions, it seems to me that a goal should be at least 300 watts of carrier. Sure you can make contacts with 25-50 watts but for consistant contacts, the higher power is the best. When guys ask me about linears, I usually advise that they shouldn't waste time on any linear with a tube or tubes with less than 1000 watts of plate dissapation. One of the best off the shelf amps is the Ameritron AL-1200 and even with that amp, when I reach 1500 watts PEP on AM the scope will start to show flattopping above that level. In addition, the smaller off the shelf SSB amps do not have the necessary beefy power supply to do AM operations at the rated PEP ratings. 73, Ken W2DTC __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
Rev. Don Sanders wrote: Ken, as I read the rules, we are only allowed to run 375 watts carrier. this is wrong. There is -no- maximum carrier limit. The only maximum power limit imposed on Ham Radio operators is 1,500W PEP output, regardless of mode. 1,500W PEP output on AM, -would- be 375w *if* you modulate that carrier with a sine-wave. We don't talk in sine-waves. Don Chester/K4KYV, Bacon/WA3WDR and John Coleman/WA5BXO collaborated on this very subject. ALL AM'ers should read this page, and read it again and when you're done, read it again. www.qsl.net/wa5bxo/asyam/aam3.html 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
In fact, since many people refuse (or just don't know how) to click on a link, allow me to paste some of that here, that is germane to the overall discussion of power levels, ratings, and class of operation of a tube. -Geoff/W5OMR = Amplitude Modulation (AM) using natural asymmetrical voice a joint effort by John, WA5BXO Bob, WA3WDR (Bacon) Tim, W5TOB Don, K4KYV When I (John) first tried AM, I had a Knight Kit T-60 transmitter, which used controlled-carrier modulation. Controlled-carrier modulation is a method of modulation that maintains a low carrier output until modulation is applied, and then the carrier will increase with the average level of modulation. This is done to keep the power consumption and heat low when you are not modulating. It was often used in rigs that were inexpensive and had components that were not sturdy enough to maintain a higher level of carrier and modulation. Modulation was accomplished by applying audio voltage to the screen grid bias voltage of the RF output tube. Controlled-carrier operation resulted from deliberate rectification of the audio waveform in sections of the modulator that were DC-coupled to the modulator output, and this was arranged to cause the average screen bias voltage to shift upward when audio was present, thereby increasing the carrier level when modulation was present. If this system was not overdriven, the resulting signal was readable, although not pleasing to the listener. The diode detector type receiver's AGC voltage would bump up and down with the carrier shift. This caused a very annoying rise and fall of background noise. Also, with loud speech, the rectifying section of the modulator could easily overperform its function. The resulting distortion was so severe that most of the audio was actually eliminated, just when it should have been the loudest! It was very difficult to avoid overdriving the modulator, without the modulation being too low to hear well. The group of hams that I wanted to join on 3850 KC just couldn’t hear me, or complained endlessly about the awful sound from my rig’s controlled carrier modulation. Their complaints were constructive, and they convinced me that I needed to upgrade my modulation technique if I was going to join in the AM fun. My solution was to build a plate modulation system. The modulating audio voltage was derived from an external audio amplifier that could deliver the proper audio voltage to the plate supply circuit of the final RF amplifier. The improvement this made in signal output and audio quality was remarkable. The group could hear me, and hear me clearly. Over time, I learned more, but the knowledge came slowly. It was almost 10 years before I really understood the circuit, and the math behind it. A lot of this understanding is due to my association with Don, K4KYV. The T-60 was typical of many relatively low-cost transmitters available to newcomers to the hobby in the years from 1960-65, and it is an example of how the manufactures were trying to sell equipment. The advertisements would say something like “Here is a transmitter that will run near the legal limit for a novice on CW and has the capability of running AM when the novice upgrades to general class.” The Knight Kit T-60 rig described above was purchased for about $70. The cost of adding the AM capability to the transmitters design was probably about $5. The external modulator that I constructed was built from scrap and hand-me-down parts, but had the parts been purchased, they would have cost more than the Knight Kit T-60. The original $5 modulator that was put into the Knight Kit T-60 was a bungled attempt to add AM capability to a low-cost transmitter, but it sold a lot of transmitters. Why was screen modulation used? Because it was inexpensive and simple. It did not require any transformers, and only small, low power tubes were needed in the modulator. Why was controlled-carrier modulation used? Mostly to reduce RF amplifier plate dissipation. Efficiency is low in a screen-modulated AM transmitter. Typical carrier efficiency is only about 35%. The typical 6146B could only produce about 15 watts of carrier power, and at 35% efficiency the plate dissipation was about 28 watts. The thought was to reduce plate dissipation when no audio was present, by reducing the carrier output. Efficiency was lower at lower output levels, but dissipation was lower, too. The idea was that average plate dissipation would be lower, so more carrier power could be produced when audio was present, without overheating the tube. However, the transmitter designs really did not produce much more usable carrier power during modulation, and distortion was so bad that this power seemed higher, but it really did little good. Some amateurs have made simple improvements to the screen modulator circuitry of the T-60 and similar
Re: [AMRadio] power ratings
Ken, as I read the rules, we are only allowed to run 375 watts carrier. With 100% modulation this will give us 1500 watts pep which is the max output allowed. ***Don, You are correct about the 1500 watts PEP. It could also be derived by 600 watts of carrier with much less than 100% modulation. There are also schemes where the carrier is almost 1000 watts and it is modulated downward at nearly 100% and still get the 1500 watts PEP. Another comment about linears in AM service. Those who do the math and run an SSB linear with the PEP equal to 4 times the carrier sometimes miss the calculation of the male voice which will usually modulate higher than 100% unless limited in the audio section. Thus many SSB amps do not have the headroom for good AM.
Re: [AMRadio] power ratings
A comment about AM transmitters. A plate modulated AM transmitter requires a modulator of 50% of the power of the final to produce 100% modulation. These transmitters like the Johnson Ranger produce better audo than the screen modulation units like the small Heaths. Only the Heath DX-100 and TX-1 (Apachee) used plate modulation. But most of the airborne military transmitters used screen modulation to reduce the weight and power requirment. These all produce very good comunication audio. But if you want broadcast quality audio you need a real plate modulated rig. Bob Macklin K5MYJ/7 Seattle, Wa. REAL RADIOS GLOW IN THE DARK - Original Message - From: kenw2dtc [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Tuesday, July 12, 2005 5:30 PM Subject: Re: [AMRadio] power ratings Ken, as I read the rules, we are only allowed to run 375 watts carrier. With 100% modulation this will give us 1500 watts pep which is the max output allowed. ***Don, You are correct about the 1500 watts PEP. It could also be derived by 600 watts of carrier with much less than 100% modulation. There are also schemes where the carrier is almost 1000 watts and it is modulated downward at nearly 100% and still get the 1500 watts PEP. Another comment about linears in AM service. Those who do the math and run an SSB linear with the PEP equal to 4 times the carrier sometimes miss the calculation of the male voice which will usually modulate higher than 100% unless limited in the audio section. Thus many SSB amps do not have the headroom for good AM. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
The best quality audio of all can be gotten from low level modulation and a linear amplifier. 73 Gary K4FMX Bob Macklin wrote: A comment about AM transmitters. A plate modulated AM transmitter requires a modulator of 50% of the power of the final to produce 100% modulation. These transmitters like the Johnson Ranger produce better audo than the screen modulation units like the small Heaths. Only the Heath DX-100 and TX-1 (Apachee) used plate modulation. But most of the airborne military transmitters used screen modulation to reduce the weight and power requirment. These all produce very good comunication audio. But if you want broadcast quality audio you need a real plate modulated rig. Bob Macklin K5MYJ/7 Seattle, Wa. REAL RADIOS GLOW IN THE DARK - Original Message - From: kenw2dtc [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Tuesday, July 12, 2005 5:30 PM Subject: Re: [AMRadio] power ratings Ken, as I read the rules, we are only allowed to run 375 watts carrier. With 100% modulation this will give us 1500 watts pep which is the max output allowed. ***Don, You are correct about the 1500 watts PEP. It could also be derived by 600 watts of carrier with much less than 100% modulation. There are also schemes where the carrier is almost 1000 watts and it is modulated downward at nearly 100% and still get the 1500 watts PEP. Another comment about linears in AM service. Those who do the math and run an SSB linear with the PEP equal to 4 times the carrier sometimes miss the calculation of the male voice which will usually modulate higher than 100% unless limited in the audio section. Thus many SSB amps do not have the headroom for good AM. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
Gary Schafer wrote: The best quality audio of all can be gotten from low level modulation and a linear amplifier. 73 Gary K4FMX However, highly non-efficient. --- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
But if you want broadcast quality audio you need a real plate modulated rig The best quality audio of all can be gotten from low level modulation and a linear amplifier. ***I disagree with both statements above. If properly set up and fixed with the proper audio chain, a plate modulated rig, a broadcast transmitter, a rice box and linear, a plate modulated rig and a linear or a class E rig could sound like broadcast quality and the listener would not be able to distinguish the difference. 73, Ken W2DTC
Re: [AMRadio] power ratings
However, highly non-efficient. Actually not TRUE. The total power pulled from power supply determines effeciency. A low level and linear consumes less power for same carrier power. See some KW mobile rigs from years ago. also I remember WCKY had 50 watts modulated carrier ( 2 megawatts pep) and it was from a LINEAR!.. my$ 0.02. Mike
Re: [AMRadio] power ratings
kenw2dtc wrote: But if you want broadcast quality audio you need a real plate modulated rig The best quality audio of all can be gotten from low level modulation and a linear amplifier. ***I disagree with both statements above. If properly set up and fixed with the proper audio chain, a plate modulated rig, a broadcast transmitter, a rice box and linear, a plate modulated rig and a linear or a class E rig could sound like broadcast quality and the listener would not be able to distinguish the difference. 73, Ken W2DTC But the difference could be measured. 73 Gary K4FMX
Re: [AMRadio] power ratings
Geoff wrote: Gary Schafer wrote: The best quality audio of all can be gotten from low level modulation and a linear amplifier. 73 Gary K4FMX However, highly non-efficient. --- 73 = Best Regards, -Geoff/W5OMR Efficiency doesn't matter anymore for hams. Output power is the limiting factor not input power. 73 Gary K4FMX
Re: [AMRadio] power ratings
Gary Schafer wrote: Geoff wrote: Gary Schafer wrote: The best quality audio of all can be gotten from low level modulation and a linear amplifier. However, highly non-efficient. Efficiency doesn't matter anymore for hams. Output power is the limiting factor not input power. I don't operate in those circles. I'm still a ham from the OLD days, when Radio was RADIO. For what some pass off as hams these days, you could do just as well to drive down to the local discount store, and buy a boom-box and plug it in. That's all it takes to be a ham these days, anyway - right? No one builds anymore. It seems like no one goes out and finds some wire, stretches out a pre-determined length and feed a peice of coax in the middle of it, to make an antenna. No, they'd rather BUY a dipole... HOLY JIMMINY! The first commercial dipole I saw for sale, I about soiled my knickers. I thought now, there's a guy with a good idea, but who's gonna pay $50 for 25' of RG-58 coax, a pair of connectors, some copper wire and a peice of pvc? That was at a hamfest, and an hour later, he was sold out. Ain't for me, man... --- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] power ratings
Didn't this subject get beat to death back in January of this year? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Power ratings
Sorry about this. I must have hit a wrong key and sent the message before I was done. Ed K6UUZ On Mon, 11 Jul 2005 08:42:39 -0700 [EMAIL PROTECTED] writes: I thought I understood these things, But I have confused me little self. I need some clear thinking here. I have a rice box rated for 100 watts SSB or 25 Watts AM. I belie __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
You will get lots of answers. the short and correct answer is 100 watts carrier with peaks to 400 watts. I run a similar one at 150 watts carrier for short periods. The reason the ricebox drops to 25 watts is because it is 100 pep am under those conditions about 17 watts is what I use to drive my 3 x 811a amp here. There was a great article in QST explaining this and I have popsted ref in the past. The amp will easily do 600 pep but YOUR supply will not, Mine will. That is why they say 400 watts PEP.. Hope this helps.. mike - Original Message - From: [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Monday, July 11, 2005 11:54 AM Subject: [AMRadio] power ratings I thought I understood these things, But I have confused me little self. I need some clear thinking here. I have a rice box rated for 100 watts SSB or 25 Watts AM. I believe the 100 watts is PEP while the 25 watts is RMS (continuous carrier). I want to add a linear amplifier to bring the 25 watts AM up considerably. I see the Ameritron AL-811 is rated for 600 watts SSB and 400 watts AM. Is this 400 watts PEP or RMS. If PEP that means the RMS rating is 100 watts, the same as my DX-100. Also it requires 75 watts of drive. Is this PEP or RMS. If RMS my rice box at 25 watts won't drive it. I am thinking the 75 watts of drive is PEP and my rice box with 100 watts PEP in AM will drive it. Can someone clarify this for me? Thanks. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] power ratings
SSB amps make poor AM amps, partly because they are built for the very small average power output/duty cycle. I would say AL-811 is good for about 100 watts carrier output tube wise, but the power supply may not be up for it. Many amps of that type use voltage doubler or tripler circuits, and stiff regulation is not their strong point. A pair of 3-500z tubes will do 400 watts of carrier I think, if the power supply can handle it, and with fans, and with a 220 volt feed Seems quite silly when you can get 700 watts of carrier out of a pair of 813's. Or 300 watts carrier out of a pair of plate modulated 811a's. If you want to get any clean power out, you likely have to run the rice box at 15 or 20 watts so you don't get into the ALC stuff, and would need to look for an amp that takes less power to drive. From 25 to 100 watts is a big jump, even if 100 watts does not sound like a lot. I think 100 watts is qrp for AM, unless you work 40 meters in the day, with a good antenna. On the other hand, the rice boxes make great exciters for class C rf decks! Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, July 11, 2005 11:55 AM To: amradio@mailman.qth.net Subject: [AMRadio] power ratings I thought I understood these things, But I have confused me little self. I need some clear thinking here. I have a rice box rated for 100 watts SSB or 25 Watts AM. I believe the 100 watts is PEP while the 25 watts is RMS (continuous carrier). I want to add a linear amplifier to bring the 25 watts AM up considerably. I see the Ameritron AL-811 is rated for 600 watts SSB and 400 watts AM. Is this 400 watts PEP or RMS. If PEP that means the RMS rating is 100 watts, the same as my DX-100. Also it requires 75 watts of drive. Is this PEP or RMS. If RMS my rice box at 25 watts won't drive it. I am thinking the 75 watts of drive is PEP and my rice box with 100 watts PEP in AM will drive it. Can someone clarify this for me? Thanks. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] power ratings
[EMAIL PROTECTED] wrote: I thought I understood these things, But I have confused me little self. I need some clear thinking here. I have a rice box rated for 100 watts SSB or 25 Watts AM. I believe the 100 watts is PEP while the 25 watts is RMS (continuous carrier). I want to add a linear amplifier to bring the 25 watts AM up considerably. I see the Ameritron AL-811 is rated for 600 watts SSB and 400 watts AM. Is this 400 watts PEP or RMS. If PEP that means the RMS rating is 100 watts, the same as my DX-100. Also it requires 75 watts of drive. Is this PEP or RMS. If RMS my rice box at 25 watts won't drive it. I am thinking the 75 watts of drive is PEP and my rice box with 100 watts PEP in AM will drive it. Can someone clarify this for me? Thanks. The general 'rule of thumb', Ed, is to load your linear up for max smoke, in CW. then, switch yoru ricebox over to AM, and adjust the carrier level up to 25% of the total output power of the amp. Then, increase your mic gain up until you just start to see a deflection on the grid meter of the amp. This should put you pretty darn close to the linear portion of your AM signal. Of course, a Scope always helps when adjusting audio levels. As for the power out of the amps and rice boxes... 25% of the max output should be sufficient for 'clean' sounding AM, in -most- rigs. 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Power ratings
Your statement sounds pretty close to me. For instance, I set my TS-430S carrier level for about 1/3 of full carrier (Ip)capability, then adjust the mic gain control until it sounds OK on my monitor or to a live contact. Do not use a compressor at all. IMHO. Good luck. 73 K0NG . Quoting [EMAIL PROTECTED]: I thought I understood these things, But I have confused me little self. I need some clear thinking here. I have a rice box rated for 100 watts SSB or 25 Watts AM. I belie __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net This message was sent using IMP, the Internet Messaging Program.
Re: [AMRadio] power ratings
Ed Shows you what high level modulation can do, with finals running in Class C vs. the amp running in linear mode. Byron, W3WKR
