KPA-1500 Efficiency As A Function of Input Power
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KPA-1500 Efficiency As A Function of Input Power
 
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Interesting data, Charles. I assumed that running the KPA1500 (or KPA500)
at lower power would keep the fan from running as much. I knew that efficiency changed with output power but I did not expect that it was this significant. If your data is correct there is 1000++ watts of heat to dissipate no matter what power level you use. John KK9A From: charles k5ua Date: Fri Aug 17 01:17:49 EDT 2018 Upon further testing, I have found that the efficiency of the KPA-1500 is varies greatly with driving power. The following table illustrates the relationships between exciter power, voltage, current, power-in(voltage x amps), power-out, efficiency, and dissipated power. The following test was made with the KPA-1500 into a dummy load and readings from the KPA-1500 utility software. (Exciter)(Amps) (Voltage) (Power-In) (Power-Out) (Efficiency Pout/Pin) (Dissipated Pwr) 10w 29a 52.7v 1528w 375W 375/1528 = 24.5% 1205w 15w 37a 52.7v 1950w 620w 620/1950 = 31.7% 1335w 20w 43a 52.6v 2262w 861w 861/2262 = 38.0% 1413w 25w 47a 52.6v 2472w 1060w 1060/2472 = 42.8% 1451w 30w 51a 52.6v 2682w 1227w 1227/2682 = 45.7% 1420w 35w 53a 52.5v 2782w 1380w 1380/2782 = 49.5% 1412w 40w 55a 52.5v 2887w 1497w 1497/2887 = 51.9% 1382w 45w 56a 52.5v 2940w 1600w 1600/2940 = 54.4% 1313w 50w 57a 52.5v 2992w 1703w 1703/2992 = 56.9% 1315w 53w 59a 52.5v 3097w 1825w 1825/3097 = 58.9% 1306w The remarkable thing is that DISSIPATED POWER appears to be relatively constant from 375w output through 1825w output. This implies the KPA-1500 will need to dissipate nearly the same amount of heat at low power output as at high power output, if I am interpreting the data correctly. I would like to know from Elecraft if this is normal behavior. Charles K5UA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
KPA-1500 Efficiency As A Function of Input Power
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"There was a similar post about the KPA500 in the last year or so. Elecraft responded that the amp was designed for 500 Watts running less was less efficient and running amp at low power was doing it no favors. "
Here is an example of measured PA dissipation for a KPA500: https://www.dropbox.com/s/bq0v2740t3iztnj/KPA500%20PA%20DISS%20for%2040%20meters.pdf?dl=0 73, Andy k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA-1500 Efficiency As A Function of Input Power
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In reply to this post by john@kk9a.com
I really do NOT understand why this data is so surprising.
It all seems to me to be perfectly normal with the amplifier's highest efficiency occurring at near max output. Which curiously, I would assume, is the way the amp was designed. Think zero output with zero drive = zero efficiency. Apply some drive, read some output and the efficiency goes up from there. 73, Charlie k3ICH -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of [hidden email] Sent: Friday, August 17, 2018 8:57 AM To: [hidden email] Cc: [hidden email] Subject: [Elecraft] KPA-1500 Efficiency As A Function of Input Power Interesting data, Charles. I assumed that running the KPA1500 (or KPA500) at lower power would keep the fan from running as much. I knew that efficiency changed with output power but I did not expect that it was this significant. If your data is correct there is 1000++ watts of heat to dissipate no matter what power level you use. John KK9A From: charles k5ua Date: Fri Aug 17 01:17:49 EDT 2018 Upon further testing, I have found that the efficiency of the KPA-1500 is varies greatly with driving power. The following table illustrates the relationships between exciter power, voltage, current, power-in(voltage x amps), power-out, efficiency, and dissipated power. The following test was made with the KPA-1500 into a dummy load and readings from the KPA-1500 utility software. (Exciter)(Amps) (Voltage) (Power-In) (Power-Out) (Efficiency Pout/Pin) (Dissipated Pwr) 10w 29a 52.7v 1528w 375W 375/1528 = 24.5% 1205w 15w 37a 52.7v 1950w 620w 620/1950 = 31.7% 1335w 20w 43a 52.6v 2262w 861w 861/2262 = 38.0% 1413w 25w 47a 52.6v 2472w 1060w 1060/2472 = 42.8% 1451w 30w 51a 52.6v 2682w 1227w 1227/2682 = 45.7% 1420w 35w 53a 52.5v 2782w 1380w 1380/2782 = 49.5% 1412w 40w 55a 52.5v 2887w 1497w 1497/2887 = 51.9% 1382w 45w 56a 52.5v 2940w 1600w 1600/2940 = 54.4% 1313w 50w 57a 52.5v 2992w 1703w 1703/2992 = 56.9% 1315w 53w 59a 52.5v 3097w 1825w 1825/3097 = 58.9% 1306w The remarkable thing is that DISSIPATED POWER appears to be relatively constant from 375w output through 1825w output. This implies the KPA-1500 will need to dissipate nearly the same amount of heat at low power output as at high power output, if I am interpreting the data correctly. I would like to know from Elecraft if this is normal behavior. Charles K5UA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA-1500 Efficiency As A Function of Input Power
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In reply to this post by ANDY DURBIN
For those curious about the reasons for high power draw at low
power out, it might be useful to review the handbook discussion of amplifiers, and the characteristics of class A, B, and C designs. 73 Bill AE6JV -------------------------------------------------------------- Bill Frantz | There are now so many exceptions to the 408-356-8506 | Fourth Amendment that it operates only by www.pwpconsult.com | accident. - William Hugh Murray ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA-1500 Efficiency As A Function of Input Power
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In reply to this post by ANDY DURBIN
I've said this and measured this for years with tube type amps, where as
I hear hams say they are running reduced power to "save the tubes". That's HOGWASH. Determine the efficiency at reduced power vs. rated power. The excessive heat at reduced power has to go somewhere. I view running an amp, tube or solid state types, at reduced power is much like driving with your right foot on the accelerator and the left foot on the brake {US style} and wondering why your gas mileage suffers and your brakes wear out. Tune it up, load it up, and run that sucker at full power. After all, ........that's why you have an amp. 73 Bob, K4TAX On 8/17/2018 8:11 AM, ANDY DURBIN wrote: > "There was a similar post about the KPA500 in the last year or so. Elecraft responded that the amp was designed for 500 Watts running less was less efficient and running amp at low power was doing it no favors." > > Here is an example of measured PA dissipation for a KPA500: > > https://www.dropbox.com/s/bq0v2740t3iztnj/KPA500%20PA%20DISS%20for%2040%20meters.pdf?dl=0 > > 73, > Andy k3wyc > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA-1500 Efficiency As A Function of Input Power
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In reply to this post by Charlie T, K3ICH
Yes yes and yes. Amps are designed with the fixed output matching
network chosen for a value of impedance and energy transfer to be at "rated power". Running any amp at reduced power then does not confirm to the design of the output matching network and the efficiency decreases. You aren't doing any favor to yourself, the amp, or others to run the amp otherwise. 73 Bob, K4TAX On 8/17/2018 8:24 AM, Charlie T wrote: > I really do NOT understand why this data is so surprising. > It all seems to me to be perfectly normal with the amplifier's highest > efficiency occurring at near max output. > Which curiously, I would assume, is the way the amp was designed. > > Think zero output with zero drive = zero efficiency. > Apply some drive, read some output and the efficiency goes up from there. > > 73, Charlie k3ICH > > > > > -----Original Message----- > From: [hidden email] <[hidden email]> On > Behalf Of [hidden email] > Sent: Friday, August 17, 2018 8:57 AM > To: [hidden email] > Cc: [hidden email] > Subject: [Elecraft] KPA-1500 Efficiency As A Function of Input Power > > Interesting data, Charles. I assumed that running the KPA1500 (or KPA500) > at lower power would keep the fan from running as much. I knew that > efficiency changed with output power but I did not expect that it was this > significant. If your data is correct there is 1000++ watts of heat to > dissipate no matter what power level you use. > > John KK9A > > > From: charles k5ua > Date: Fri Aug 17 01:17:49 EDT 2018 > > Upon further testing, I have found that the efficiency of the KPA-1500 is > varies greatly with driving power. The following table illustrates the > relationships between exciter power, voltage, current, power-in(voltage x > amps), power-out, efficiency, and dissipated power. > The following test was made with the KPA-1500 into a dummy load and readings > from the KPA-1500 utility software. > > (Exciter)(Amps) (Voltage) (Power-In) (Power-Out) (Efficiency Pout/Pin) > (Dissipated Pwr) > 10w 29a 52.7v 1528w 375W 375/1528 = 24.5% > 1205w > 15w 37a 52.7v 1950w 620w 620/1950 = 31.7% > 1335w > 20w 43a 52.6v 2262w 861w 861/2262 = 38.0% > 1413w > 25w 47a 52.6v 2472w 1060w 1060/2472 = 42.8% > 1451w > 30w 51a 52.6v 2682w 1227w 1227/2682 = 45.7% > 1420w > 35w 53a 52.5v 2782w 1380w 1380/2782 = 49.5% > 1412w > 40w 55a 52.5v 2887w 1497w 1497/2887 = 51.9% > 1382w > 45w 56a 52.5v 2940w 1600w 1600/2940 = 54.4% > 1313w > 50w 57a 52.5v 2992w 1703w 1703/2992 = 56.9% > 1315w > 53w 59a 52.5v 3097w 1825w 1825/3097 = 58.9% > 1306w > > The remarkable thing is that DISSIPATED POWER appears to be relatively > constant from 375w output through 1825w output. This implies the > KPA-1500 will need to dissipate nearly the same amount of heat at low power > output as at high power output, if I am interpreting the data correctly. I > would like to know from Elecraft if this is normal behavior. > > Charles K5UA > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html Message > delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Charlie T, K3ICH
Well, only if you've figured out a way to divide by zero. [:-)
The term "amplifier efficiency" must have changed dramatically since I worked in broadcast nearly a lifetime ago. Then, it was the ratio [expressed as a percentage] of the RF power delivered to the 3 1/8" hardline divided by the DC power supplied to the amplifier plate circuit. Power to the filaments was generally excluded by manufacturers seeking to have higher efficiency numbers. One 10 KW FM transmitter I helped build used four 4-1000A's in parallel and the filament power was 600 watts. Efficiency, including filament power was just over 70%. To measure the efficiency of a KPA1500 [or 500, or KXPA100, or KPA2] one would measure the key down RF output and divide it by the key down DC input power. If it was water-cooled, I suppose one should include the input power to the pump(s), but no one ever did. SS amplifiers like the KPA(1)500 probably run class AB<mumble> or its equivalent and have substantial DC input power even at zero RF input. RF output power vs RF input power defines the amplifer's transfer function, not its efficiency. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County PS: I really don't recommend trying to get four parallel 4-1000A's to work anything close to "well" at 90.7 MHz. Apparently, it seemed like a good idea at the time. [:-) On 8/17/2018 6:24 AM, Charlie T wrote: > Think zero output with zero drive = zero efficiency. > Apply some drive, read some output and the efficiency goes up from there. > > 73, Charlie k3ICH > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA-1500 Efficiency As A Function of Input Power
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And I would guess it was running in class C, which is not
linear, so only useful for certain modes (including FM). Class C can convert most of the input power to RF power. 73 Bill AE6JV On 8/17/18 at 11:48 AM, [hidden email] (Fred Jensen) wrote: >One 10 KW FM transmitter I helped build used four 4-1000A's in >parallel and the filament power was 600 watts. Efficiency, >including filament power was just over 70%. ----------------------------------------------------------------------- Bill Frantz | Ham radio contesting is a | Periwinkle (408)356-8506 | contact sport. | 16345 Englewood Ave www.pwpconsult.com | - Ken Widelitz K6LA / VY2TT | Los Gatos, CA 95032 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Actually a class C amplifier can be made to perform as a linear. The technology is over 60 years old but I don’t think it has ever been tried in amateur service.
Sent from my iPad > On Aug 17, 2018, at 3:06 PM, Bill Frantz <[hidden email]> wrote: > > And I would guess it was running in class C, which is not linear, so only useful for certain modes (including FM). Class C can convert most of the input power to RF power. > > 73 Bill AE6JV > >> On 8/17/18 at 11:48 AM, [hidden email] (Fred Jensen) wrote: >> >> One 10 KW FM transmitter I helped build used four 4-1000A's in parallel and the filament power was 600 watts. Efficiency, including filament power was just over 70%. > ----------------------------------------------------------------------- > Bill Frantz | Ham radio contesting is a | Periwinkle > (408)356-8506 | contact sport. | 16345 Englewood Ave > www.pwpconsult.com | - Ken Widelitz K6LA / VY2TT | Los Gatos, CA 95032 > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by k6dgw
Today in broadcast we generally rate transmitters by AC in to RF out. For AM transmitters that figure is in the low 90 percent range and the current FMs run at about 74% AC in to RF out.
Sent from my iPad > On Aug 17, 2018, at 11:48 AM, Fred Jensen <[hidden email]> wrote: > > Well, only if you've figured out a way to divide by zero. [:-) > > The term "amplifier efficiency" must have changed dramatically since I worked in broadcast nearly a lifetime ago. Then, it was the ratio [expressed as a percentage] of the RF power delivered to the 3 1/8" hardline divided by the DC power supplied to the amplifier plate circuit. Power to the filaments was generally excluded by manufacturers seeking to have higher efficiency numbers. One 10 KW FM transmitter I helped build used four 4-1000A's in parallel and the filament power was 600 watts. Efficiency, including filament power was just over 70%. > > To measure the efficiency of a KPA1500 [or 500, or KXPA100, or KPA2] one would measure the key down RF output and divide it by the key down DC input power. If it was water-cooled, I suppose one should include the input power to the pump(s), but no one ever did. SS amplifiers like the KPA(1)500 probably run class AB<mumble> or its equivalent and have substantial DC input power even at zero RF input. > > RF output power vs RF input power defines the amplifer's transfer function, not its efficiency. > > 73, > > Fred ["Skip"] K6DGW > Sparks NV DM09dn > Washoe County > > PS: I really don't recommend trying to get four parallel 4-1000A's to work anything close to "well" at 90.7 MHz. Apparently, it seemed like a good idea at the time. [:-) > >> On 8/17/2018 6:24 AM, Charlie T wrote: >> Think zero output with zero drive = zero efficiency. >> Apply some drive, read some output and the efficiency goes up from there. >> >> 73, Charlie k3ICH >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Bill Frantz
Yes, it was Class C ... FM is constant envelope modulation. The ancient
50's/60's rules of thumb were: Class A: 25% - really linear Class B: 50% - linear with crossover distortion Class C: 75% - exceedingly non-linear Class AB1: between A & B, no grid current - mitigates crossover distortion Class AB2: AB1 but draws grid current - also mitigates crossover dist. For audio, Classes B and AB<mumble> needed two tubes and operated push-pull. We were interested in efficiency of the PA because higher efficiency meant lower dissipation for a fixed output [10 KW]. As it was, at 90.7 MHz, the anodes were already nearly white. Again ... I do not recommend using four parallel 4-1000A's anywhere near 90.7 MHz. [:-)) The RCA Ampliphase [aka "Amplifuzz"] series of AM transmitters ran Class C through the entire RF chain. They were a bear to align ... you never wanted to start a PoP after sign-off if you'd been awake all day. The Ampliphase history is moderately interesting however, especially if you're from or in Sacramento CA. This thread however has been discussing "efficiency" of a KPA1500 in terms of output power vs drive power which isn't even remotely close to measuring efficiency. As amateurs, I can't come up with a single reason why we'd be concerned about efficiency as long as the amplifier design is solid and robust. Our A/C uses far more energy over a summer than my K3/KPA500 did all year, and I leave it on a lot. If this is all about fans and their noise, the thread needs a new subject. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/17/2018 3:06 PM, Bill Frantz wrote: > And I would guess it was running in class C, which is not linear, so > only useful for certain modes (including FM). Class C can convert most > of the input power to RF power. > > 73 Bill AE6JV > > On 8/17/18 at 11:48 AM, [hidden email] (Fred Jensen) wrote: > >> One 10 KW FM transmitter I helped build used four 4-1000A's in >> parallel and the filament power was 600 watts. Efficiency, including >> filament power was just over 70%. > ----------------------------------------------------------------------- > Bill Frantz | Ham radio contesting is a | Periwinkle > (408)356-8506 | contact sport. | 16345 Englewood Ave > www.pwpconsult.com | - Ken Widelitz K6LA / VY2TT | Los Gatos, CA 95032 > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by W2xj
Yes. Electricity cost to generate the RF that earns the revenue is a
major part of the broadcast station budget. Not so much for amateurs. Since FM is constant envelope modulation, it makes sense it would have a lower overall efficiency. Even Rush Limbaugh has to take a breath occasionally on AM ... it makes no difference on FM. [:-)) 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 8/17/2018 3:45 PM, W2xj wrote: > Today in broadcast we generally rate transmitters by AC in to RF out. For AM transmitters that figure is in the low 90 percent range and the current FMs run at about 74% AC in to RF out. > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Seems like this discussion would be functional if it were ways to quiet the fans without compromising the efficiency of the cooling.
Chuck Jack KE9UW Sent from my iPhone, cjack > On Aug 17, 2018, at 7:13 PM, Fred Jensen <[hidden email]> wrote: > > Yes. Electricity cost to generate the RF that earns the revenue is a major part of the broadcast station budget. Not so much for amateurs. Since FM is constant envelope modulation, it makes sense it would have a lower overall efficiency. Even Rush Limbaugh has to take a breath occasionally on AM ... it makes no difference on FM. [:-)) > > 73, > > Fred ["Skip"] K6DGW > Sparks NV DM09dn > Washoe County > >> On 8/17/2018 3:45 PM, W2xj wrote: >> Today in broadcast we generally rate transmitters by AC in to RF out. For AM transmitters that figure is in the low 90 percent range and the current FMs run at about 74% AC in to RF out. >> >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email]
Chuck, KE9UW
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Re: KPA-1500 Efficiency As A Function of Input Power
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In reply to this post by k6dgw
Also on this related thread:
We're way over the posting limit on this one. Let's close this thread for now. (And, in the future, please voluntarily close long threads well before I happen to stop by :-) 73, Eric /elecraft.com/ On 8/17/2018 5:13 PM, Fred Jensen wrote: > Yes. Electricity cost to generate the RF that earns the revenue is a major > part of the broadcast station budget. Not so much for amateurs. Since FM is > constant envelope modulation, it makes sense it would have a lower overall > efficiency. Even Rush Limbaugh has to take a breath occasionally on AM ... it > makes no difference on FM. [:-)) > > 73, ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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