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#1
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Power amps/watts consumption query?
I would be grateful for the advice of one of our technically minded
members: The new radio I have coming merely states it's power consumption as 210VA, as it is a multivoltage radio. What consumption in watts/amps does this translate to at 240 volts AC mains? Also. if I used an inverter to drive it off a 12 volt DC battery, what would the power consumption in amps then be? A friend who helped me wrote: Watts = Volts * Amperes so 210VA = 210 Watts 210 Watts means 210 / 240 Amps which is .875 Amps. If you want to use a 12V battery, 210 Watts means 210 / 12 Amps or 17.5 Amps. This assumes the AC supply is as efficient as the DC supply. It won't actually be quite as efficient, so you're likely to need fewer Amps, maybe 14 or 15 but that's a guess. Maybe you can ask as the DC current depends on their design which is not known to us yet. Those numbers look very high to me. I suspect they've made a little mistake. I replied: it does seem very high to me for 210VA. at 240 volts AC mains. As just a poor guess I would estimate 0.5 amps at 240 volts AC mains and 8 amps at 12v DC but I cannot calculate it. _______________________________ So what do the experts out there think? Would be grateful for your help. John Plimmer, Montagu, Western Cape Province, South Africa South 33 d 47 m 32 s, East 20 d 07 m 32 s RX Icom IC-756 PRO III with MW mods Drake SW8 & ERGO software Sony 7600D, GE SRIII, Redsun RP2100 BW XCR 30, Sangean 803A. Antenna's RF Systems DX 1 Pro Mk II, Datong AD-270 Kiwa MW Loop, PAORDT Roelof mini-whip http://www.dxing.info/about/dxers/plimmer.dx |
#2
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Power amps/watts consumption query?
Thanks for that Lamont.
The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA The result you and my other friend get (which is the same) seems enormous. John Plimmer, Montagu, Western Cape Province, South Africa South 33 d 47 m 32 s, East 20 d 07 m 32 s RX Icom IC-756 PRO III with MW mods Drake SW8 & ERGO software Sony 7600D, GE SRIII, Redsun RP2100 BW XCR 30, Sangean 803A. Antenna's RF Systems DX 1 Pro Mk II, Datong AD-270 Kiwa MW Loop, PAORDT Roelof mini-whip http://www.dxing.info/about/dxers/plimmer.dx On Feb 9, 12:17*am, "The Shadow" wrote: wrote in message ... I would be grateful for the advice of one of our technically minded members: The new radio I have coming merely states it's power consumption as 210VA, as it is a multivoltage radio. What consumption in watts/amps does this translate to at 240 volts AC mains? Also. if I used an inverter to drive it off a 12 volt DC battery, what would the power consumption in amps then be? POWER CONSUMPTION IS IN WATTS NOT AMPS A friend who helped me wrote: Watts = Volts * Amperes so 210VA = 210 Watts NOT TRUE - WATTS = V*A*COSINE OF THE PHASE ANGLE 210 Watts means 210 / 240 Amps which is .875 Amps. If you want to use a 12V battery, 210 Watts means 210 / 12 Amps or 17.5 Amps. This assumes the AC supply is as efficient as the DC supply. It won't actually be quite as efficient, so you're likely to need fewer Amps, maybe 14 or 15 but that's a guess. Maybe you can ask as the DC current depends on their design which is not known to us yet. Those numbers look very high to me. I suspect they've made a little mistake. I replied: it does seem very high to me for 210VA. at 240 volts AC mains. As just a poor guess I would estimate 0.5 amps at 240 volts AC mains and 8 amps at 12v DC but I cannot calculate it. _______________________________ So what do the experts out there think? Would be grateful for your help. WHAT KIND OF RADIO IS IT -- 210 VA IS TOO HIGH FOR A RECEIVER -- MORE LIKE A TRANSCEIVER Volt-Amperes VA usually refers to AC apparent power - it takes into account reacive components see URL:http://www.allaboutcircuits.com/vol_2/chpt_11/2..html True power in an AC circuit is IxE if there are no reactive components otherwise it is I squared R or ExI x Cos theta So True Power (Watts) does not equal VA unless the circuit is purely resistive. Assuming your device is resisive (or near to it) then see URL:http://www.sengpielaudio.com/calculator-ohm.htm which indeed gives 0.875 Amperes Again usinghttp://www.sengpielaudio.com/calculator-ohm.htm which indeed gives 17.5 Amperes Allowing for efficiencies and loss etc I would allow for 20 to 25 amperes Most inverters will specify a power rating Lamont- Hide quoted text - - Show quoted text - |
#3
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Power amps/watts consumption query?
wrote in message ... Thanks for that Lamont. The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA Wow John those figures are high -- is it a tube type radio? Example a solid state Icom IC-746 PRO - URL: http://www.icomamerica.com/en/produc...fications.aspx Power supply requirement 13.8V DC ±15% Power consumption Tx Max. power 23A Rx Standby 2.2A Max. audio 3.0A That's 317 Watts Tx and 41 Watts Rx (max figures) Lamont |
#4
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Power amps/watts consumption query?
"The Shadow" wrote in message ... wrote in message ... Thanks for that Lamont. The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA Wow John those figures are high -- is it a tube type radio? 210VA = 95.55W 850VA = 386.75W Does sound like a tube rig. |
#5
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Power amps/watts consumption query?
In article ,
"The Shadow" wrote: wrote in message ... I would be grateful for the advice of one of our technically minded members: The new radio I have coming merely states it's power consumption as 210VA, as it is a multivoltage radio. What consumption in watts/amps does this translate to at 240 volts AC mains? Also. if I used an inverter to drive it off a 12 volt DC battery, what would the power consumption in amps then be? POWER CONSUMPTION IS IN WATTS NOT AMPS A friend who helped me wrote: Watts = Volts * Amperes so 210VA = 210 Watts NOT TRUE - WATTS = V*A*COSINE OF THE PHASE ANGLE 210 Watts means 210 / 240 Amps which is .875 Amps. If you want to use a 12V battery, 210 Watts means 210 / 12 Amps or 17.5 Amps. This assumes the AC supply is as efficient as the DC supply. It won't actually be quite as efficient, so you're likely to need fewer Amps, maybe 14 or 15 but that's a guess. Maybe you can ask as the DC current depends on their design which is not known to us yet. Those numbers look very high to me. I suspect they've made a little mistake. I replied: it does seem very high to me for 210VA. at 240 volts AC mains. As just a poor guess I would estimate 0.5 amps at 240 volts AC mains and 8 amps at 12v DC but I cannot calculate it. _______________________________ So what do the experts out there think? Would be grateful for your help. WHAT KIND OF RADIO IS IT -- 210 VA IS TOO HIGH FOR A RECEIVER -- MORE LIKE A TRANSCEIVER Volt-Amperes VA usually refers to AC apparent power - it takes into account reacive components see URL: http://www.allaboutcircuits.com/vol_2/chpt_11/2.html True power in an AC circuit is IxE if there are no reactive components otherwise it is I squared R or ExI x Cos theta So True Power (Watts) does not equal VA unless the circuit is purely resistive. Assuming your device is resisive (or near to it) then see URL: http://www.sengpielaudio.com/calculator-ohm.htm which indeed gives 0.875 Amperes Again using http://www.sengpielaudio.com/calculator-ohm.htm which indeed gives 17.5 Amperes Allowing for efficiencies and loss etc I would allow for 20 to 25 amperes Most inverters will specify a power rating As you noted above 210 Watts is to much power for a receiver. Chances are then the VA the OP refers to is apparent AC power or peak power. In order to answer the PO's question if we assume AC 210VA peak power I have found that for most power supplies, which are full wave rectified followed by larger capacitance a figure of about a third works well. Then the AC real power would be 74 watts. Then to get to DC we need the RMS value of the AC real power, which is a factor of 2.828 so about 26 watts RMS. At 12 Volts to drive the inverter would be about 2 amps DC. I'm making plenty of assumptions here. You will be somewhat more than 2.1 amps depending on the inverter efficiency. Lets use a figure of 80% so the battery current draw would then be about 2.5 amps. 26 watts and 2.1 amps are rational numbers for todays solid state receivers. A lot of assumptions but it seems to make sense. -- Telamon Ventura, California |
#6
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Power amps/watts consumption query?
On Feb 8, 4:40*pm, wrote:
Thanks for that Lamont. The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA The result you and my other friend get (which is the same) seems enormous. John Plimmer, Montagu, Western Cape Province, South Africa South 33 d 47 m 32 s, East 20 d 07 m 32 s RX Icom IC-756 PRO III with MW mods Drake SW8 & ERGO software Sony 7600D, GE SRIII, Redsun RP2100 BW XCR 30, Sangean 803A. Antenna's RF Systems DX 1 Pro Mk II, Datong AD-270 Kiwa MW Loop, PAORDT Roelof mini-whiphttp://www.dxing.info/about/dxers/plimmer.dx On Feb 9, 12:17*am, "The Shadow" wrote: wrote in message ... I would be grateful for the advice of one of our technically minded members: The new radio I have coming merely states it's power consumption as 210VA, as it is a multivoltage radio. What consumption in watts/amps does this translate to at 240 volts AC mains? Also. if I used an inverter to drive it off a 12 volt DC battery, what would the power consumption in amps then be? POWER CONSUMPTION IS IN WATTS NOT AMPS A friend who helped me wrote: Watts = Volts * Amperes so 210VA = 210 Watts NOT TRUE - WATTS = V*A*COSINE OF THE PHASE ANGLE 210 Watts means 210 / 240 Amps which is .875 Amps. If you want to use a 12V battery, 210 Watts means 210 / 12 Amps or 17.5 Amps. This assumes the AC supply is as efficient as the DC supply. It won't actually be quite as efficient, so you're likely to need fewer Amps, maybe 14 or 15 but that's a guess. Maybe you can ask as the DC current depends on their design which is not known to us yet. Those numbers look very high to me. I suspect they've made a little mistake. I replied: it does seem very high to me for 210VA. at 240 volts AC mains. As just a poor guess I would estimate 0.5 amps at 240 volts AC mains and 8 amps at 12v DC but I cannot calculate it. _______________________________ So what do the experts out there think? Would be grateful for your help. WHAT KIND OF RADIO IS IT -- 210 VA IS TOO HIGH FOR A RECEIVER -- MORE LIKE A TRANSCEIVER Volt-Amperes VA usually refers to AC apparent power - it takes into account reacive components see URL:http://www.allaboutcircuits.com/vol_2/chpt_11/2.html True power in an AC circuit is IxE if there are no reactive components otherwise it is I squared R or ExI x Cos theta So True Power (Watts) does not equal VA unless the circuit is purely resistive. Assuming your device is resisive (or near to it) then see URL:http://www..sengpielaudio.com/calculator-ohm.htm which indeed gives 0.875 Amperes Again usinghttp://www.sengpielaudio.com/calculator-ohm.htm which indeed gives 17.5 Amperes Allowing for efficiencies and loss etc I would allow for 20 to 25 amperes Most inverters will specify a power rating Lamont- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - JP, Message - "New Radio in South Africa" http://groups.google.com/group/rec.r...866d6ff18a951c I am getting another RX, an Icom IC-7700 see brochure at: http://www.ab4oj.com/icom/ic7700/IC-7700_pre.pdf ICOM IC-7700 - http://www.rigpix.com/icom/ic7700.htm Minute-Video - http://www.youtube.com/watch?v=eJS0z-Y5hKc You are talking about your new Icom IC-7700 Transceiver. IC7700 - http://www.ab4oj.com/icom/ic7700/main.html Icom IC-7700 Transceiver - Rated Power Consumption : Tx Max. power 800 VA {Transmit 'Power Output' Mode} Rx Stand-by 200 VA (typ.) {Receive Only Listening Mode} Max. Audio 210 VA (typ.) {Receive Only Maximum Audio Output} 12 VOLT DC POWER SOURCE / SUPPLY - = FOR RECEIVE ONLY USE = - [NO MIC CONNECTED / NO TRANSMITTING] 240 Volts divide by 12 Volts = 20 f# 0.875 Amperes @ 240 Volts 0.875 Amperes times 20 f# = 17.5 Amperes @ 12 Volts Add a 15% Power Supply Safety Factor : 17.5 Amperes times 15% (0.15) = 2.63 Amperes 17.5 Amperes plus 2.63 Amperes = 20.13 Amperes Requires as a Minimum a 12 Volt DC Power Supply that is Rated at 20+ Amperes. {25 Amps would be better.} FWIW - Going from 240 VAC to 120 VAC the 0.875 Amperes would become 1.75 Amperes {2 Amps} Again these Rough Numbers are for "Receive Only" Use -NOT- Transmit. ~RHF |
#7
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Power amps/watts consumption query?
No, it's not a tube rig, it's the latest Icom IC-7700.
See the spec sheet at the end of the brochu http://www.ab4oj.com/icom/ic7700/IC-7700_pre.pdf John Plimmer, Montagu South Africa On Feb 9, 4:42*am, "Brenda Ann" wrote: "The Shadow" wrote in message ... wrote in message ... Thanks for that Lamont. The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA Wow John those figures are high -- is it a tube type radio? 210VA = 95.55W 850VA = 386.75W Does sound like a tube rig. |
#8
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Power amps/watts consumption query?
"Brenda Ann" wrote in message ... "The Shadow" wrote in message ... wrote in message ... Thanks for that Lamont. The device is a transceiver and the power usage on: Transmit is 850VA and on Receive is 210VA Wow John those figures are high -- is it a tube type radio? 210VA = 95.55W 850VA = 386.75W Does sound like a tube rig. Golly Brenda how does 210VA = 95.55W 850VA = 386.75W wikipedia on volt-ampere A volt-ampere in electrical terms, means the amount of apparent power in an alternating current circuit equal to a current of one ampere at an emf of one volt. It is equivalent to watts for non-reactive circuits. Are you using peak, rms, or average factors? I assume the VA figures given by John are rms values thus RMS voltage is the amount of dc voltage that is required for producing the same amount of power as the ac waveform URL on rms voltage http://www.free-ed.net/sweethaven/Mo....asp?iNum=0102 Lamont |
#9
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Power amps/watts consumption query?
"The Shadow" wrote in message ... Golly Brenda how does 210VA = 95.55W 850VA = 386.75W wikipedia on volt-ampere A volt-ampere in electrical terms, means the amount of apparent power in an alternating current circuit equal to a current of one ampere at an emf of one volt. It is equivalent to watts for non-reactive circuits. Are you using peak, rms, or average factors? I assume the VA figures given by John are rms values The calculator used assumes a power factor of .70. It is right in line with the calculations used for USP'es in their V/A to W conversions. |
#10
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Power amps/watts consumption query?
In article ,
"Brenda Ann" wrote: "The Shadow" wrote in message ... Golly Brenda how does 210VA = 95.55W 850VA = 386.75W wikipedia on volt-ampere A volt-ampere in electrical terms, means the amount of apparent power in an alternating current circuit equal to a current of one ampere at an emf of one volt. It is equivalent to watts for non-reactive circuits. Are you using peak, rms, or average factors? I assume the VA figures given by John are rms values The calculator used assumes a power factor of .70. It is right in line with the calculations used for USP'es in their V/A to W conversions. The reason is the power supply input impedance is not resistive and worse the bridge diodes will only conduct on the AC peaks thus the power factor correction and the VA being a peak value not RMS. -- Telamon Ventura, California |
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