Re: [Elecraft] K3 - Power cable voltage drop
As Bob has pointed out, power drop is not the factor in the voltage to
an Elecraft transceiver.
No matter what the supply voltage may be, the K2/K3/K3S/KX2/KX3 will
attempt to produce the output power requested by the power knob setting.
Those transceivers actually measure the output power rather than the
drive level as is done by many other transceivers.
The problem is that the transmit IMD increases as the voltage drops, so
running with a higher voltage results in a cleaner signal on the air.
Of course, if you are an "all knobs right" operator, you may notice a
bit of a drop in the maximum power available on some bands. Instead of
114 watts, you may get only 95 or 100 watts, but that is extreme.
I recommend that you do not set the power knob above 100 watts in any
case. Use the maximum setting only for testing into a dummy load.
The difference between 114 watts and 100 watts is only 0.57 dB and will
not be noticed on the far end of the transmission.
73,
Don W3FPR
On 12/28/2019 5:32 PM, Bob McGraw K4TAX wrote:
It is not quite that simple. Power drop is not really a factor.
The operating range of the radio, from specifications, is 11 volts
minimum to 15 volts maximum. Thus with a 4 volt operating range, a 1
volt drop represents a 25% change. Within this range of 11 to 15 volts
the radio will attempt to deliver 100 watts by demanding the required
amount of current from the power supply. Thus the three resistances in
series example, as I stated earlier, with the middle one {radio} being a
variable value.
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Re: [Elecraft] K3 - Power cable voltage drop
It is not quite that simple. Power drop is not really a factor.
The operating range of the radio, from specifications, is 11 volts
minimum to 15 volts maximum. Thus with a 4 volt operating range, a 1
volt drop represents a 25% change. Within this range of 11 to 15 volts
the radio will attempt to deliver 100 watts by demanding the required
amount of current from the power supply. Thus the three resistances in
series example, as I stated earlier, with the middle one {radio} being a
variable value.
Therefore the resistance of the DC power cables will then cause more
voltage drop to occur as the current demand increases. This has been
noted to cause the transmitter IMD {Inter-Modulation Distortion} to
significantly increase. Much has been written here regarding attaining
lowest IMD while operating at near maximum rated voltage. A word of
caution, NEVER allow the power supply to exceed 15 volts. It is very
important to maintain minimum voltage drop with the power cables and
anything else in the path. Those power distribution strips are horrible
in this regard and should NEVER be used to power the radio. The radio
should always be connected direct to the power supply terminals. No
exceptions.
For this and other reasons, I have my power supply set to 14.8 volts at
no load. In transmit with 100 watts output and current of 17.5 amps,
the voltage indicated by the radio is 14.5 volts or 0.3 volt drop {14.8
- 14.5 = 0.3}. The calculated resistance of my power cables is then E
/ I = R or 0.5 / 17.5 = 0.017 ohms.
In conclusion, it is NOT power output that is of concern.
73
Bob, K4TAX
On 12/28/2019 1:49 PM, shull2...@gmail.com wrote:
At what point does a drop in input power become significant? Does a 1.0v loss
translate to 10 times less output power than a 0.1v loss?
-Original Message-
From: elecraft-boun...@mailman.qth.net On
Behalf Of Bob McGraw K4TAX
Sent: Saturday, December 28, 2019 1:07 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 - Power cable voltage drop
Actually 1 ohm of total resistance from a 14V source and a 20A load would be
more than excessive. More like a 0.01 ohm is 0.20 volt drop for 20 amps. I x
R = E
View it as 3 series resistors across a 14 V source. R-1 is the DC POS lead
resistance, the radio which is a variable resistance as R-2, and
R-3 which is the DC NEG lead resistance. Therefore, the voltage at the radio
is equal to the IR drop being the sum of R-1 and R-3.
73
Bob, K4TAX
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Re: [Elecraft] K3 - Power cable voltage drop
At what point does a drop in input power become significant? Does a 1.0v loss translate to 10 times less output power than a 0.1v loss? -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Bob McGraw K4TAX Sent: Saturday, December 28, 2019 1:07 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 - Power cable voltage drop Actually 1 ohm of total resistance from a 14V source and a 20A load would be more than excessive. More like a 0.01 ohm is 0.20 volt drop for 20 amps. I x R = E View it as 3 series resistors across a 14 V source. R-1 is the DC POS lead resistance, the radio which is a variable resistance as R-2, and R-3 which is the DC NEG lead resistance. Therefore, the voltage at the radio is equal to the IR drop being the sum of R-1 and R-3. 73 Bob, K4TAX On 12/28/2019 11:26 AM, Michael Walker wrote: > For measuring voltage drop.. I would measure the voltage drop from the > Plus lead of the Power supply to the plus lead on the back of the > radio while in full load TX (FM or RTTY). > > It should be less than 0.1 or 0.2 of a volt. > > Then, do the same on the Negative Lead. You should see the same > answer (assuming Negative DC doesn't find an alternative path). > > Those numbers should add up to the same voltage drop total. > > As a reminder. It only takes 1 ohm of loss in the cable/fuses to > significantly impact your full power out. > > Mike va3mw > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to shull2...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Actually 1 ohm of total resistance from a 14V source and a 20A load would be more than excessive. More like a 0.01 ohm is 0.20 volt drop for 20 amps. I x R = E View it as 3 series resistors across a 14 V source. R-1 is the DC POS lead resistance, the radio which is a variable resistance as R-2, and R-3 which is the DC NEG lead resistance. Therefore, the voltage at the radio is equal to the IR drop being the sum of R-1 and R-3. 73 Bob, K4TAX On 12/28/2019 11:26 AM, Michael Walker wrote: For measuring voltage drop.. I would measure the voltage drop from the Plus lead of the Power supply to the plus lead on the back of the radio while in full load TX (FM or RTTY). It should be less than 0.1 or 0.2 of a volt. Then, do the same on the Negative Lead. You should see the same answer (assuming Negative DC doesn't find an alternative path). Those numbers should add up to the same voltage drop total. As a reminder. It only takes 1 ohm of loss in the cable/fuses to significantly impact your full power out. Mike va3mw __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
For measuring voltage drop.. I would measure the voltage drop from the Plus lead of the Power supply to the plus lead on the back of the radio while in full load TX (FM or RTTY). It should be less than 0.1 or 0.2 of a volt. Then, do the same on the Negative Lead. You should see the same answer (assuming Negative DC doesn't find an alternative path). Those numbers should add up to the same voltage drop total. As a reminder. It only takes 1 ohm of loss in the cable/fuses to significantly impact your full power out. Mike va3mw On Sat, Dec 28, 2019 at 11:00 AM Don Wilhelm wrote: > Better precision than a battery can be found by using a precision > voltage regulator. Take a look at the Precision Voltage Source on my > website www.w3fpr.com. > > 73, > Don W3FPR > > On 12/27/2019 5:53 PM, Bill Frantz wrote: > > A simple reality test for a volt meter is to measure a fresh battery. > > Zinc/carbon or Alkaline should show about 1.56 volts. (I learned this > > test from the bias setting instructions for a Dynakit Stereo 70 > > amplifier. They built the amp so the test point read 1.56 volts when the > > bias is correctly set and suggested calibrating your meter with a > > battery. In that era, the zinc/carbon battery was what ran almost all of > > the flashlights (torches for for English speakers) in the world. > > > > 73 Bill AE6JV > > > > On 12/23/19 at 11:30 PM, rmcg...@blomand.net (Bob McGraw K4TAX) wrote: > > > >> A good, known accurate DVM is an asset to any station. Use it to > >> determine if the others are accurate. There are several good brands > >> available. A DVM that is not accurate is worse than no DVM at all. > >> My choice of many years ago is my Fluke 77. After I tapped it with > >> too much voltage, I sent it to Fluke for repair and calibration. I am > >> confident when I make a measurement it is accurate without question. > > - > > Bill Frantz| The first thing you need when | Periwinkle > > (408)356-8506 | using a perimeter defense is a | 16345 Englewood Ave > > www.pwpconsult.com | perimeter. | Los Gatos, CA > 95032 > > > > __ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to donw...@embarqmail.com > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to va...@portcredit.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Better precision than a battery can be found by using a precision voltage regulator. Take a look at the Precision Voltage Source on my website www.w3fpr.com. 73, Don W3FPR On 12/27/2019 5:53 PM, Bill Frantz wrote: A simple reality test for a volt meter is to measure a fresh battery. Zinc/carbon or Alkaline should show about 1.56 volts. (I learned this test from the bias setting instructions for a Dynakit Stereo 70 amplifier. They built the amp so the test point read 1.56 volts when the bias is correctly set and suggested calibrating your meter with a battery. In that era, the zinc/carbon battery was what ran almost all of the flashlights (torches for for English speakers) in the world. 73 Bill AE6JV On 12/23/19 at 11:30 PM, rmcg...@blomand.net (Bob McGraw K4TAX) wrote: A good, known accurate DVM is an asset to any station. Use it to determine if the others are accurate. There are several good brands available. A DVM that is not accurate is worse than no DVM at all. My choice of many years ago is my Fluke 77. After I tapped it with too much voltage, I sent it to Fluke for repair and calibration. I am confident when I make a measurement it is accurate without question. - Bill Frantz | The first thing you need when | Periwinkle (408)356-8506 | using a perimeter defense is a | 16345 Englewood Ave www.pwpconsult.com | perimeter. | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to donw...@embarqmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
A simple reality test for a volt meter is to measure a fresh battery. Zinc/carbon or Alkaline should show about 1.56 volts. (I learned this test from the bias setting instructions for a Dynakit Stereo 70 amplifier. They built the amp so the test point read 1.56 volts when the bias is correctly set and suggested calibrating your meter with a battery. In that era, the zinc/carbon battery was what ran almost all of the flashlights (torches for for English speakers) in the world. 73 Bill AE6JV On 12/23/19 at 11:30 PM, rmcg...@blomand.net (Bob McGraw K4TAX) wrote: A good, known accurate DVM is an asset to any station. Use it to determine if the others are accurate. There are several good brands available. A DVM that is not accurate is worse than no DVM at all. My choice of many years ago is my Fluke 77. After I tapped it with too much voltage, I sent it to Fluke for repair and calibration. I am confident when I make a measurement it is accurate without question. - Bill Frantz| The first thing you need when | Periwinkle (408)356-8506 | using a perimeter defense is a | 16345 Englewood Ave www.pwpconsult.com | perimeter. | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I would leave it at 4.96 as that tells me it was set at some point (from 5.00 default). However, if you think the internal metering is wrong, you could double check it if you have a calibrated meter. Valid range of ADC REF setting is 4.75 to 5.25 and I typically see the correct value around 4.85 to 5.05. To experiment, I checked at 5.25 and 4.75 Set at 5.25 the internal volt meter displayed 14.2V. Set at 4.75 it showed 12.9V That is a 1.3 volt swing so it is worth setting properly. Keith WE6R On 12/26/2019 3:39 PM, Mike Flowers wrote: Hi Keith, Mine reads 4.96, so should it be set to 5.0 or left alone? Thanks. - 73 and good DX de Mike, K6MKF, NCDXC Secretary -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Keith Trinity WE6R Sent: Thursday, December 26, 2019 15:25 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 - Power cable voltage drop Notes for all; Check the K3 config menu item "ADC REF". If at 5.00 it is probably at default. (if at 4.00 a glitch occurred, probably during FW update, and will FUBAR the internal metering. Set to 5.00 or read on). (I check this during checkout, so if it has been in for Service, it should be OK). Higher accuracy of the K3 items like the internal Volt-Meter can be had if this is set properly. With a known external meter on Pin 2 to ground of the 15 pin ACCY connector; Go into config menu ADC REF and set it. Also you can stick your probes into the Anderson connectors at the back of the radio during full power TX to see the actual voltage to the radio. (I have a digital LED meter connected with small wires to the Anderson supply wire right at the back of the radio on my K3 test bench). Keith WE6R __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to mike.flow...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Hi Keith, Mine reads 4.96, so should it be set to 5.0 or left alone? Thanks. - 73 and good DX de Mike, K6MKF, NCDXC Secretary > -Original Message- > From: elecraft-boun...@mailman.qth.net > On Behalf Of Keith Trinity WE6R > Sent: Thursday, December 26, 2019 15:25 > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 - Power cable voltage drop > > Notes for all; > Check the K3 config menu item "ADC REF". If at 5.00 it is probably at > default. > (if at 4.00 a glitch occurred, probably during FW update, and will FUBAR the > internal metering. Set to 5.00 or read on). > (I check this during checkout, so if it has been in for Service, it should be OK). > > Higher accuracy of the K3 items like the internal Volt-Meter can be had if this is > set properly. > With a known external meter on Pin 2 to ground of the 15 pin ACCY connector; > Go into config menu ADC REF and set it. > > Also you can stick your probes into the Anderson connectors at the back of the > radio during full power TX to see the actual voltage to the radio. > (I have a digital LED meter connected with small wires to the Anderson supply > wire right at the back of the radio on my K3 test bench). > Keith WE6R > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html Message > delivered to mike.flow...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Notes for all; Check the K3 config menu item "ADC REF". If at 5.00 it is probably at default. (if at 4.00 a glitch occurred, probably during FW update, and will FUBAR the internal metering. Set to 5.00 or read on). (I check this during checkout, so if it has been in for Service, it should be OK). Higher accuracy of the K3 items like the internal Volt-Meter can be had if this is set properly. With a known external meter on Pin 2 to ground of the 15 pin ACCY connector; Go into config menu ADC REF and set it. Also you can stick your probes into the Anderson connectors at the back of the radio during full power TX to see the actual voltage to the radio. (I have a digital LED meter connected with small wires to the Anderson supply wire right at the back of the radio on my K3 test bench). Keith WE6R __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Concur. -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Vic Rosenthal Sent: Tuesday, December 24, 2019 9:34 PM To: hawley, charles j jr Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 - Power cable voltage drop I have a Fluke DVM also. I gulped when I bought it some 30+ years ago, but it was a good decision. It’s like a Snap-On wrench. It just feels right and never let me down. Victor 4X6GP > On 25 Dec 2019, at 4:29, hawley, charles j jr wrote: > > I have a Fluke 87...for a couple of decades now. It does it all well. > > Chuck Jack Hawley > KE9UW > > Sent from my iPhone, cjack > >> On Dec 23, 2019, at 10:31 PM, Bob McGraw K4TAX wrote: >> >> A good, known accurate DVM is an asset to any station. Use it to determine >> if the others are accurate. There are several good brands available. A >> DVM that is not accurate is worse than no DVM at all. >> >> My choice of many years ago is my Fluke 77. After I tapped it with too >> much voltage, I sent it to Fluke for repair and calibration. I am confident >> when I make a measurement it is accurate without question. >> >> Bob, K4TAX >> >> >> Sent from my iPhone >> >>>> On Dec 23, 2019, at 2:12 PM, Buck wrote: >>> >>> The reliable place to measure the voltage at the K3x is using the supply >>> voltage display meter in the radio. I was surprised to find mine was >>> significantly low. I thought it was voltage drop but changing the supply >>> cable didn't make much difference. >>> >>> Turns out the Astron power supply was more than a volt low and the meter on >>> the supply had been cranked up to make it appear to be correct. I used two >>> separate VOMs to set the power supply and then adjusted the meter to make >>> it agree. >>> >>> Moral of the story: don't rely on the meter on the power supply and assume >>> a low reading at the radio is due solely to voltage drop. >>> >>> >>> >>> Buck, k4ia >>> Honor Roll >>> 8BDXCC >>> EasyWayHamBooks.com >>> >>>>> On 12/23/2019 2:26 PM, Phil Kane wrote: >>>>> On 12/22/2019 9:44 AM, Bob McGraw wrote: >>>>> I also added a dedicated ground between the ground screw on the >>>>> back of the radio to the ground screw on the power supply. >>>> That's for "bonding". Where do you pick up "ground" - at the >>>> radio, at the PS, or at some other point? >>>> 73 de K2ASP - Phil Kane >>>> Elecraft K2/100 s/n 5402 >>>> From a Clearing in the Silicon Forest Beaverton (Washington County) >>>> Oregon >>>> __ >>>> Elecraft mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:Elecraft@mailman.qth.net This list hosted by: >>>> http://www.qsl.net Please help support this email list: >>>> http://www.qsl.net/donate.html Message delivered to >>>> radiok...@gmail.com >>> __ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net Please help support this >>> email list: http://www.qsl.net/donate.html Message delivered to >>> rmcg...@blomand.net >> >> >> __ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net Please help support this >> email list: http://www.qsl.net/donate.html Message delivered to >> c-haw...@illinois.edu > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > k2vco@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to gthorn...@thorntonmostullaw.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I have a Fluke DVM also. I gulped when I bought it some 30+ years ago, but it was a good decision. It’s like a Snap-On wrench. It just feels right and never let me down. Victor 4X6GP > On 25 Dec 2019, at 4:29, hawley, charles j jr wrote: > > I have a Fluke 87...for a couple of decades now. It does it all well. > > Chuck Jack Hawley > KE9UW > > Sent from my iPhone, cjack > >> On Dec 23, 2019, at 10:31 PM, Bob McGraw K4TAX wrote: >> >> A good, known accurate DVM is an asset to any station. Use it to determine >> if the others are accurate. There are several good brands available. A >> DVM that is not accurate is worse than no DVM at all. >> >> My choice of many years ago is my Fluke 77. After I tapped it with too >> much voltage, I sent it to Fluke for repair and calibration. I am confident >> when I make a measurement it is accurate without question. >> >> Bob, K4TAX >> >> >> Sent from my iPhone >> On Dec 23, 2019, at 2:12 PM, Buck wrote: >>> >>> The reliable place to measure the voltage at the K3x is using the supply >>> voltage display meter in the radio. I was surprised to find mine was >>> significantly low. I thought it was voltage drop but changing the supply >>> cable didn't make much difference. >>> >>> Turns out the Astron power supply was more than a volt low and the meter on >>> the supply had been cranked up to make it appear to be correct. I used two >>> separate VOMs to set the power supply and then adjusted the meter to make >>> it agree. >>> >>> Moral of the story: don't rely on the meter on the power supply and assume >>> a low reading at the radio is due solely to voltage drop. >>> >>> >>> >>> Buck, k4ia >>> Honor Roll >>> 8BDXCC >>> EasyWayHamBooks.com >>> > On 12/23/2019 2:26 PM, Phil Kane wrote: > On 12/22/2019 9:44 AM, Bob McGraw wrote: > I also added a dedicated ground between the ground screw on the back of > the radio to the ground screw on the power supply. That's for "bonding". Where do you pick up "ground" - at the radio, at the PS, or at some other point? 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to radiok...@gmail.com >>> __ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to rmcg...@blomand.net >> >> >> __ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to c-haw...@illinois.edu > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to k2vco@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Yes true. However seeing they way some hams configure their stations, building or modifying and implementing a power supply with voltage sensing, is of serious questionable nature. Likewise, in conditions where power supplies are buried under the desk. One needs to see the volt meter when the supply is first turned on to assure the voltage is correct. And that should be done before the radio is turned on. Oh I know about crowbar circuits, but if that $2.50 part fails it will likely take out a $3000 radio. This just isn't smart. Having worked with equipment that was supplied with 35 ft or 50 ft power cables for loads of 20A to 30A at + & - 18 volts, I understand just a wee bit about voltage sensing circuits and what makes them oscillate. Just err on the safe side. And for ham radio, it likely is not necessary to have or implement remote voltage sensing. Wire and connectors are cheap. Use a shorter length of wire or larger gauge wire. There's no likely component failure with this approach. 73 Bob, K4TAX On 12/24/2019 8:25 PM, K9MA wrote: Typically, there are small resistors at the power supply between the output and sense terminals to prevent the voltage from rising if a sense wire opens up. 73, Scott K9MA -- Scott Ellington --- via iPad On Dec 24, 2019, at 5:39 PM, Bob McGraw K4TAX wrote: Yes, but one screw-up on the remote sensing system and it will take advantage of the voltage overhead on the pass transistors and likely wipe out every piece of equipment. I strongly do not advise it. And you make a valid point for NOT using remote sensing. 73 Bob, K4TAX On 12/24/2019 3:22 PM, Jim Rhodes wrote: I have thought about doing that. Just requires a 2 wire hookup with small gauge wire. But I run all of my small items like the remoterig box, LP-pan box, VHF/UHF rig and so forth off of the main supply and if I have a larger than anticipated voltage drop on rig power cable the voltage on the other tings could go fairly high. The power supply is a HB thing with at least a 50 amp capacity and plenty of voltage overhead before pass transistors. (Used to run 2 HF rigs before downsizing.) On Tue, Dec 24, 2019 at 2:25 PM Rose wrote: First, it would require some basic technical skill ... (;-) 73 K0PP On Tue, Dec 24, 2019, 13:20 Karin Johnson wrote: Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to elecraftcov...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jimk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to k...@sdellington.us __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I have a Fluke 87...for a couple of decades now. It does it all well. Chuck Jack Hawley KE9UW Sent from my iPhone, cjack > On Dec 23, 2019, at 10:31 PM, Bob McGraw K4TAX wrote: > > A good, known accurate DVM is an asset to any station. Use it to determine > if the others are accurate. There are several good brands available. A DVM > that is not accurate is worse than no DVM at all. > > My choice of many years ago is my Fluke 77. After I tapped it with too much > voltage, I sent it to Fluke for repair and calibration. I am confident when > I make a measurement it is accurate without question. > > Bob, K4TAX > > > Sent from my iPhone > >> On Dec 23, 2019, at 2:12 PM, Buck wrote: >> >> The reliable place to measure the voltage at the K3x is using the supply >> voltage display meter in the radio. I was surprised to find mine was >> significantly low. I thought it was voltage drop but changing the supply >> cable didn't make much difference. >> >> Turns out the Astron power supply was more than a volt low and the meter on >> the supply had been cranked up to make it appear to be correct. I used two >> separate VOMs to set the power supply and then adjusted the meter to make it >> agree. >> >> Moral of the story: don't rely on the meter on the power supply and assume a >> low reading at the radio is due solely to voltage drop. >> >> >> >> Buck, k4ia >> Honor Roll >> 8BDXCC >> EasyWayHamBooks.com >> On 12/23/2019 2:26 PM, Phil Kane wrote: On 12/22/2019 9:44 AM, Bob McGraw wrote: I also added a dedicated ground between the ground screw on the back of the radio to the ground screw on the power supply. >>> That's for "bonding". Where do you pick up "ground" - at the radio, at >>> the PS, or at some other point? >>> 73 de K2ASP - Phil Kane >>> Elecraft K2/100 s/n 5402 >>> From a Clearing in the Silicon Forest >>> Beaverton (Washington County) Oregon >>> __ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to radiok...@gmail.com >> __ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to rmcg...@blomand.net > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to c-haw...@illinois.edu __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Typically, there are small resistors at the power supply between the output and sense terminals to prevent the voltage from rising if a sense wire opens up. 73, Scott K9MA -- Scott Ellington --- via iPad > On Dec 24, 2019, at 5:39 PM, Bob McGraw K4TAX wrote: > > Yes, but one screw-up on the remote sensing system and it will take > advantage of the voltage overhead on the pass transistors and likely wipe out > every piece of equipment. I strongly do not advise it. And you make a > valid point for NOT using remote sensing. > > 73 > > Bob, K4TAX > >> On 12/24/2019 3:22 PM, Jim Rhodes wrote: >> I have thought about doing that. Just requires a 2 wire hookup with small >> gauge wire. But I run all of my small items like the remoterig box, LP-pan >> box, VHF/UHF rig and so forth off of the main supply and if I have a larger >> than anticipated voltage drop on rig power cable the voltage on the other >> tings could go fairly high. The power supply is a HB thing with at least a >> 50 amp capacity and plenty of voltage overhead before pass transistors. >> (Used to run 2 HF rigs before downsizing.) >> >> >>> On Tue, Dec 24, 2019 at 2:25 PM Rose wrote: >>> >>> First, it would require some basic technical skill ... (;-) >>> >>> 73 >>> >>> K0PP >>> >>> On Tue, Dec 24, 2019, 13:20 Karin Johnson >>> wrote: >>> Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to elecraftcov...@gmail.com >>> __ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to jimk...@gmail.com >>> >> > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to k...@sdellington.us __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Yes, but one screw-up on the remote sensing system and it will take advantage of the voltage overhead on the pass transistors and likely wipe out every piece of equipment. I strongly do not advise it. And you make a valid point for NOT using remote sensing. 73 Bob, K4TAX On 12/24/2019 3:22 PM, Jim Rhodes wrote: I have thought about doing that. Just requires a 2 wire hookup with small gauge wire. But I run all of my small items like the remoterig box, LP-pan box, VHF/UHF rig and so forth off of the main supply and if I have a larger than anticipated voltage drop on rig power cable the voltage on the other tings could go fairly high. The power supply is a HB thing with at least a 50 amp capacity and plenty of voltage overhead before pass transistors. (Used to run 2 HF rigs before downsizing.) On Tue, Dec 24, 2019 at 2:25 PM Rose wrote: First, it would require some basic technical skill ... (;-) 73 K0PP On Tue, Dec 24, 2019, 13:20 Karin Johnson wrote: Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to elecraftcov...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jimk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
With the Astron supplies, the 723 regulator does have provision for remote sensing. And with a bit of work and some extra wiring and components one can have remote sensing. I would suggest NOT doing so as remote sensing become "inputs" to the 723 regulator chip and any noise or RF on the remote sensing lines can be very problematic. Proper filtering and time constants will be required to prevent oscillations. My suggestion is to use good quality #10 AWG wire, such as auto primary wire fitted with correct terminals on the ends. Be sure to correctly crimp and solder as needed. Suggested length is something less than 10 ft. Also be sure to have a dedicated ground between the ground screw on the back of the radio to the ground on the power supply. In the end, if you desire to have remote sensing, purchase a suitable supply that provides remote sensing. Life will be much easier. 73 Bob, K4TAX On 12/24/2019 2:20 PM, Karin Johnson wrote: Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to rmcg...@blomand.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
There can be stability issues with remote sensing. Also RF susceptibility. Take care! 73, Scott K9MA -- Scott Ellington --- via iPad > On Dec 24, 2019, at 4:03 PM, Don Wilhelm wrote: > > That would be a neat thing to do, but DO NOT do that on a power supply that > is connected to anything other than the rig you are sensing from. > > The voltage on other devices connected to the power supply will increase when > you transmit on the rig to which the sense wires are connected. > > Use a separate power supply for accessories. > > If you need to use the same supply, you can adjust the voltage upward - the > SS30 sold by Elecraft already has an output voltage of 14.1 volts. > Still use a separate power cable to the transceiver and another cable to any > distribution box that you use for accessories for best results (lowest > voltage drop when transmitting). > > 73, > Don W3FPR > >> On 12/24/2019 4:23 PM, K4HYJ via Elecraft wrote: >> I do use voltage sensing at the rear of the radio. Astron supplies can be >> modified easily to do this - they already have sense wires tied to the >> voltage output terminals. Basically you disconnect them there and run leads >> (keep em short) to the radio. On transmit, my K3s drops less than 1/10 a >> volt. >> There are a few write ups floating around on how to do this. I installed a >> switch (make before break type) on my RS-50M so I can return to "normal" >> sensing. ***WARNING*** If the external sense wires are not connected to >> anything the crowbar circuit will fire!!! > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to k...@sdellington.us __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
That would be a neat thing to do, but DO NOT do that on a power supply that is connected to anything other than the rig you are sensing from. The voltage on other devices connected to the power supply will increase when you transmit on the rig to which the sense wires are connected. Use a separate power supply for accessories. If you need to use the same supply, you can adjust the voltage upward - the SS30 sold by Elecraft already has an output voltage of 14.1 volts. Still use a separate power cable to the transceiver and another cable to any distribution box that you use for accessories for best results (lowest voltage drop when transmitting). 73, Don W3FPR On 12/24/2019 4:23 PM, K4HYJ via Elecraft wrote: I do use voltage sensing at the rear of the radio. Astron supplies can be modified easily to do this - they already have sense wires tied to the voltage output terminals. Basically you disconnect them there and run leads (keep em short) to the radio. On transmit, my K3s drops less than 1/10 a volt. There are a few write ups floating around on how to do this. I installed a switch (make before break type) on my RS-50M so I can return to "normal" sensing. ***WARNING*** If the external sense wires are not connected to anything the crowbar circuit will fire!!! __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I do use voltage sensing at the rear of the radio. Astron supplies can be modified easily to do this - they already have sense wires tied to the voltage output terminals. Basically you disconnect them there and run leads (keep em short) to the radio. On transmit, my K3s drops less than 1/10 a volt. There are a few write ups floating around on how to do this. I installed a switch (make before break type) on my RS-50M so I can return to "normal" sensing. ***WARNING*** If the external sense wires are not connected to anything the crowbar circuit will fire!!! Hank K4HYJ -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Karin Johnson Sent: Tuesday, December 24, 2019 3:20 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K3 - Power cable voltage drop Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to h...@optilink.us __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I have thought about doing that. Just requires a 2 wire hookup with small gauge wire. But I run all of my small items like the remoterig box, LP-pan box, VHF/UHF rig and so forth off of the main supply and if I have a larger than anticipated voltage drop on rig power cable the voltage on the other tings could go fairly high. The power supply is a HB thing with at least a 50 amp capacity and plenty of voltage overhead before pass transistors. (Used to run 2 HF rigs before downsizing.) On Tue, Dec 24, 2019 at 2:25 PM Rose wrote: > First, it would require some basic technical skill ... (;-) > > 73 > > K0PP > > On Tue, Dec 24, 2019, 13:20 Karin Johnson > wrote: > > > Why hasn't anyone used remote sensing at the radio voltage input? > > As far as I know all of the Astron supplies don't have external sense > > wiring. Many so called professional grade high current supplies provide > > For external connection of the voltage sense back to the regulator chip. > > I've toyed with this idea a bit but haven't had the time dig in to the > > Astron supply I have. If this were implemented then one could maintain > > 13.8 volts or whatever you desired at the radio power supply inputs, > > Regardless of the current draw. > > > > Karin Anne Johnson K3UU > > > > > > __ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to elecraftcov...@gmail.com > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jimk...@gmail.com > -- Jim K0XU j...@rhodesend.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
First, it would require some basic technical skill ... (;-) 73 K0PP On Tue, Dec 24, 2019, 13:20 Karin Johnson wrote: > Why hasn't anyone used remote sensing at the radio voltage input? > As far as I know all of the Astron supplies don't have external sense > wiring. Many so called professional grade high current supplies provide > For external connection of the voltage sense back to the regulator chip. > I've toyed with this idea a bit but haven't had the time dig in to the > Astron supply I have. If this were implemented then one could maintain > 13.8 volts or whatever you desired at the radio power supply inputs, > Regardless of the current draw. > > Karin Anne Johnson K3UU > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to elecraftcov...@gmail.com > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] K3 - Power cable voltage drop
Why hasn't anyone used remote sensing at the radio voltage input? As far as I know all of the Astron supplies don't have external sense wiring. Many so called professional grade high current supplies provide For external connection of the voltage sense back to the regulator chip. I've toyed with this idea a bit but haven't had the time dig in to the Astron supply I have. If this were implemented then one could maintain 13.8 volts or whatever you desired at the radio power supply inputs, Regardless of the current draw. Karin Anne Johnson K3UU __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
A good, known accurate DVM is an asset to any station. Use it to determine if the others are accurate. There are several good brands available. A DVM that is not accurate is worse than no DVM at all. My choice of many years ago is my Fluke 77. After I tapped it with too much voltage, I sent it to Fluke for repair and calibration. I am confident when I make a measurement it is accurate without question. Bob, K4TAX Sent from my iPhone > On Dec 23, 2019, at 2:12 PM, Buck wrote: > > The reliable place to measure the voltage at the K3x is using the supply > voltage display meter in the radio. I was surprised to find mine was > significantly low. I thought it was voltage drop but changing the supply > cable didn't make much difference. > > Turns out the Astron power supply was more than a volt low and the meter on > the supply had been cranked up to make it appear to be correct. I used two > separate VOMs to set the power supply and then adjusted the meter to make it > agree. > > Moral of the story: don't rely on the meter on the power supply and assume a > low reading at the radio is due solely to voltage drop. > > > > Buck, k4ia > Honor Roll > 8BDXCC > EasyWayHamBooks.com > >> On 12/23/2019 2:26 PM, Phil Kane wrote: >>> On 12/22/2019 9:44 AM, Bob McGraw wrote: >>> I also added a dedicated ground between the ground screw on the back of >>> the radio to the ground screw on the power supply. >> That's for "bonding". Where do you pick up "ground" - at the radio, at >> the PS, or at some other point? >> 73 de K2ASP - Phil Kane >> Elecraft K2/100 s/n 5402 >> From a Clearing in the Silicon Forest >> Beaverton (Washington County) Oregon >> __ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to radiok...@gmail.com > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to rmcg...@blomand.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I do not use a “ground” at the station. I don’t find or see that it’s needed. My station has a 4 wire #10 service from the breaker panel to the operating position. The breakers are single 20A units. This gives me 240V for the amp and a duplex off of each leg. Thus I maintain a common neutral and common ground to the breaker panel. Grounding for lightning protection is done outside of the house and that system is bonded back to the AC Mains ground rod below the service entrance. Bob, K4TAX Sent from my iPhone > On Dec 23, 2019, at 1:44 PM, Phil Kane wrote: > > On 12/22/2019 9:44 AM, Bob McGraw wrote: > >> I also added a dedicated ground between the ground screw on the back of >> the radio to the ground screw on the power supply. > > That's for "bonding". Where do you pick up "ground" - at the radio, at > the PS, or at some other point? > > 73 de K2ASP - Phil Kane > Elecraft K2/100 s/n 5402 > > From a Clearing in the Silicon Forest > Beaverton (Washington County) Oregon > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to rmcg...@blomand.net > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
The reliable place to measure the voltage at the K3x is using the supply voltage display meter in the radio. I was surprised to find mine was significantly low. I thought it was voltage drop but changing the supply cable didn't make much difference. Turns out the Astron power supply was more than a volt low and the meter on the supply had been cranked up to make it appear to be correct. I used two separate VOMs to set the power supply and then adjusted the meter to make it agree. Moral of the story: don't rely on the meter on the power supply and assume a low reading at the radio is due solely to voltage drop. Buck, k4ia Honor Roll 8BDXCC EasyWayHamBooks.com On 12/23/2019 2:26 PM, Phil Kane wrote: On 12/22/2019 9:44 AM, Bob McGraw wrote: I also added a dedicated ground between the ground screw on the back of the radio to the ground screw on the power supply. That's for "bonding". Where do you pick up "ground" - at the radio, at the PS, or at some other point? 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to radiok...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
On 12/22/2019 9:44 AM, Bob McGraw wrote: > I also added a dedicated ground between the ground screw on the back of > the radio to the ground screw on the power supply. That's for "bonding". Where do you pick up "ground" - at the radio, at the PS, or at some other point? 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 >From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
On 12/22/2019 9:44 AM, Bob McGraw wrote: Rid your station of the DC power strip. It will cause problems. More connections in the path will be more DC voltage drip. The radios should be connected direct to the power supply. Yes and no. My station has direct short runs from a 100Ah Bioenne LiFePO4 battery to my two K3s. The radio very close to the battery is #10; the longer run (about five ft) to the radio on the other side of the desk is two #10s in parallel. This battery is used because it's operating voltage remains well about 13VDC throughout its discharge curve (as opposed to the SLA, which is closer to 11.5VDC under load). The difference results in lower IMD. The other 12V gear (and LED strips for task lighting) runs from a 100Ah 12V SLA battery through a DC power strip. All the gear is bonded together. Both batteries are float-charged by spare Thinkpad power supplies with Genasun charge regulators. The power strips are fine for low current drain devices, but, as Bob notes, not for the radios. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I used to run my K3S with an auto turn on Rigrunner which I liked very much, convenient. But the voltage drop was concerning. I go direct now to the rig. Chuck Jack Hawley KE9UW Sent from my iPhone, cjack > On Dec 22, 2019, at 10:21 AM, Don Wilhelm wrote: > > Tony, > > While those figures with the 10 gauge wire are good, they would be better if > you ran the K3 power directly from the power supply rather than from the > power distribution strip. > > Each connection will have some voltage drop, so in addition to increasing the > wiring gauge, reducing the connection points will help just as much. > > 73 Merry Christmas, or Happy Hanukkah whichever you choose to celebrate. > Don W3FPR > >> On 12/22/2019 10:47 AM, N2TK via Elecraft wrote: >> I have been using an Astron SS-30M power supply for several years to feed >> two K3's. >> I use 12ga wire from the power supply to an MFJ-4012 power strip. From the >> power strip I use 12ga wire to each K3. Total length from power supply to a >> K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's were >> tested one at a time. The power supply voltage went from 14.38 to 14.30 at >> 100W. >> Both K3's read the same on the K3's internal voltmeter - 14.1V in receive >> and 12.7V at 100W setting on the K3's. The P3 read 107W out. >> Changed the cable to 10ga wire direct from the power supply to each K3. >> Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. >> Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' of >> 10ga wire. >> P3 output was now 114W. > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to c-haw...@illinois.edu __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
I still connect all of the equipment which used walwarts to my power supply. I made provisions to have many many DC connections, as described below, to my supplies. All of my DC power leads have the correct size crimp ring terminal for the application. Never use stranded wire around a screw. Thus many problems solved. I know the DC distribution strips look cool with their LEDs and fuses and connectors, and are very easy to use for convenience. But I find just like AC strips, are a source of many problems. I've found many of the AC strips which have a poor 3rd wire connection. They are a matter of convenience and not of reliable functionality. As to the Astron SS-30M, I have 3 of those. They are great. I did find the provided DC connections where the wires are inserted into the blocks and secured with a screw from the side would not accommodate the 4 needs for DC at my station.Therefore, I took two pieces of 2" x 10-32 brass machine screw, cut off the head, filed a small flat spot on one side at the end to make it slightly D shaped. Inserted that end into the DC connector and tightened the set screw against the flat spot. Then added as needed the brass nuts, flat washers and lock washers, secured finally by another brass nut. This in effect gives me very adequate terminal length to attach as many DC power leads with suitable ring terminals as needed. DC resistance has therefore been minimized. The 10 ga wire is a good addition for radio power needs. I also added a dedicated ground between the ground screw on the back of the radio to the ground screw on the power supply. 73 Bob, K4TAX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
In my current station layout the rack-mounted Astron-50M is separated from the radio shelf, so I need a 15-foot run of cable. The Astron runs 14.2 vdc. I have 13.69 v at the main power strip (handles 10ga wiring). The primary dc power cable is No. 6 welding cable (more flexible than std No. 6) so I have a BUSS30 fuse at the main power strip. The Astron is capable of 50 amps if the main cable were to short (cable is rated for a over 200A for welding). I use the std power cord that came with my K3/10 and see 13.3v displayed by the K3 in transmit with 10w RF output. The K3/10 does not draw a lot of current. I drive a KXPA100 which has 5-foot Elecraft power cable (looks like No.12). I get 100w on all bands with about 5w drive (only 6m requires 8w drive for 80w output). I have not measured the voltage at the power-pole connector when in transmit but should be approx 13.5v based on current draw of 20 A. I run several high power solid-state amplifiers that draw up to 50A at 50v so paying attention to dc voltage drop in dc wiring is quite important. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubus...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Bob, The power strip is gone for the K3's. Now direct connections from the PS to each K3. The power strip is good for replacing the walwarts. N2TK, Tony -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Bob McGraw Sent: Sunday, December 22, 2019 12:45 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 - Power cable voltage drop Rid your station of the DC power strip. It will cause problems. More connections in the path will be more DC voltage drip. The radios should be connected direct to the power supply. As to the Astron SS-30M, I have 3 of those. They are great. I did find the provided DC connections where the wires are inserted into the blocks and secured with a screw from the side would not accommodate the 4 needs for DC at my station.Therefore, I took two pieces of 2" x 10-32 brass machine screw, cut off the head, filed a small flat spot on one side at the end to make it slightly D shaped. Inserted that end into the DC connector and tightened the set screw against the flat spot. Then added as needed the brass nuts, flat washers and lock washers, secured finally by another brass nut. This in effect gives me very adequate terminal length to attach as many DC power leads with suitable ring terminals as needed. DC resistance has therefore been minimized. The 10 ga wire is a good addition for radio power needs. I also added a dedicated ground between the ground screw on the back of the radio to the ground screw on the power supply. 73 Bob, K4TAX 12/22/2019 10:47 AM, N2TK via Elecraft wrote: > I have been using an Astron SS-30M power supply for several years to > feed two K3's. > I use 12ga wire from the power supply to an MFJ-4012 power strip. From > the power strip I use 12ga wire to each K3. Total length from power > supply to a > K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's > were tested one at a time. The power supply voltage went from 14.38 to > 14.30 at 100W. > Both K3's read the same on the K3's internal voltmeter - 14.1V in > receive and 12.7V at 100W setting on the K3's. The P3 read 107W out. > Changed the cable to 10ga wire direct from the power supply to each K3. > Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. > Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' > of 10ga wire. > P3 output was now 114W. > I never transmit with both K3's at the same time. > Just a data point. > 73 and Merry Christmas > N2TK, Tony > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > rmcg...@blomand.net > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to tony@verizon.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Hi Don, With the 10ga wire the power distribution strip is not used. There are two runs of 7' each direct from the power supply to a K3. The run is 7' because I have the power supply with the rest of my supplies, router, etc. all mounted underneath my desk to the side to keep the desktop clean. I don't hink 0.6V drop is too much to be concerned with. The amps are in the basement. In the process of adding Green Heron Everywhere wireless remotes to eliminate the manual switches too. 73 and merry Christmas N2TK, Tony -Original Message- From: Don Wilhelm Sent: Sunday, December 22, 2019 11:21 AM To: tony@verizon.net; elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 - Power cable voltage drop Tony, While those figures with the 10 gauge wire are good, they would be better if you ran the K3 power directly from the power supply rather than from the power distribution strip. Each connection will have some voltage drop, so in addition to increasing the wiring gauge, reducing the connection points will help just as much. 73 Merry Christmas, or Happy Hanukkah whichever you choose to celebrate. Don W3FPR On 12/22/2019 10:47 AM, N2TK via Elecraft wrote: > I have been using an Astron SS-30M power supply for several years to > feed two K3's. > I use 12ga wire from the power supply to an MFJ-4012 power strip. From > the power strip I use 12ga wire to each K3. Total length from power > supply to a > K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's > were tested one at a time. The power supply voltage went from 14.38 to > 14.30 at 100W. > Both K3's read the same on the K3's internal voltmeter - 14.1V in > receive and 12.7V at 100W setting on the K3's. The P3 read 107W out. > Changed the cable to 10ga wire direct from the power supply to each K3. > Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. > Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' > of 10ga wire. > P3 output was now 114W. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Rid your station of the DC power strip. It will cause problems. More connections in the path will be more DC voltage drip. The radios should be connected direct to the power supply. As to the Astron SS-30M, I have 3 of those. They are great. I did find the provided DC connections where the wires are inserted into the blocks and secured with a screw from the side would not accommodate the 4 needs for DC at my station. Therefore, I took two pieces of 2" x 10-32 brass machine screw, cut off the head, filed a small flat spot on one side at the end to make it slightly D shaped. Inserted that end into the DC connector and tightened the set screw against the flat spot. Then added as needed the brass nuts, flat washers and lock washers, secured finally by another brass nut. This in effect gives me very adequate terminal length to attach as many DC power leads with suitable ring terminals as needed. DC resistance has therefore been minimized. The 10 ga wire is a good addition for radio power needs. I also added a dedicated ground between the ground screw on the back of the radio to the ground screw on the power supply. 73 Bob, K4TAX 12/22/2019 10:47 AM, N2TK via Elecraft wrote: I have been using an Astron SS-30M power supply for several years to feed two K3's. I use 12ga wire from the power supply to an MFJ-4012 power strip. From the power strip I use 12ga wire to each K3. Total length from power supply to a K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's were tested one at a time. The power supply voltage went from 14.38 to 14.30 at 100W. Both K3's read the same on the K3's internal voltmeter - 14.1V in receive and 12.7V at 100W setting on the K3's. The P3 read 107W out. Changed the cable to 10ga wire direct from the power supply to each K3. Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' of 10ga wire. P3 output was now 114W. I never transmit with both K3's at the same time. Just a data point. 73 and Merry Christmas N2TK, Tony __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to rmcg...@blomand.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3 - Power cable voltage drop
Tony, While those figures with the 10 gauge wire are good, they would be better if you ran the K3 power directly from the power supply rather than from the power distribution strip. Each connection will have some voltage drop, so in addition to increasing the wiring gauge, reducing the connection points will help just as much. 73 Merry Christmas, or Happy Hanukkah whichever you choose to celebrate. Don W3FPR On 12/22/2019 10:47 AM, N2TK via Elecraft wrote: I have been using an Astron SS-30M power supply for several years to feed two K3's. I use 12ga wire from the power supply to an MFJ-4012 power strip. From the power strip I use 12ga wire to each K3. Total length from power supply to a K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's were tested one at a time. The power supply voltage went from 14.38 to 14.30 at 100W. Both K3's read the same on the K3's internal voltmeter - 14.1V in receive and 12.7V at 100W setting on the K3's. The P3 read 107W out. Changed the cable to 10ga wire direct from the power supply to each K3. Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' of 10ga wire. P3 output was now 114W. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] K3 - Power cable voltage drop
I have been using an Astron SS-30M power supply for several years to feed two K3's. I use 12ga wire from the power supply to an MFJ-4012 power strip. From the power strip I use 12ga wire to each K3. Total length from power supply to a K3 was 8'. Each K3 is set for 100W on 30M into a dummy load. The K3's were tested one at a time. The power supply voltage went from 14.38 to 14.30 at 100W. Both K3's read the same on the K3's internal voltmeter - 14.1V in receive and 12.7V at 100W setting on the K3's. The P3 read 107W out. Changed the cable to 10ga wire direct from the power supply to each K3. Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30. Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' of 10ga wire. P3 output was now 114W. I never transmit with both K3's at the same time. Just a data point. 73 and Merry Christmas N2TK, Tony __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
