Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Jim Brown 

On 4/26/2020 7:28 PM, N4ZR wrote:
did you have to draw a Colpitts oscillator?  IIRC, that was on my 
General exam in 1955. 


Yep. It was one of several we had to learn. :)

With the power strip, what's wrong with measuring the voltage in and 
out, knowing the current being drawn, and deriving the resistance from 
that?


Because most instrumentation available to hams isn't accurate enough.

73, Jim K9YC


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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Bill Frantz 
Having helped teach a number of Tech level ham crams, Ohm's law 
and diodes are both on the test. I'm not sure that all of the 
nitty gritty of diodes -- voltage drop by type etc. are covered though.


I think you can pass not knowing either though. :-(

73 Bill AE6JV

On 4/26/20 at 6:24 PM, [email protected] (Jim Brown) wrote:

The thing I find baffling (or depressing) here is that we all 
had to understand Ohm's Law to pass the exam for our license, 
and it's REAL simple.  Take resistance values from a wire 
table, multiply by the length, then by two for the two 
conductors, then by the current. I dunno what the exam is like 
nowadays -- my experience was 1955 with the Novice test and a 
year later with the General -- but surely there must be 
something about how diodes work!

-
Bill Frantz| The first thing you need when  | Periwinkle
(408)348-7900  | using a perimeter defense is a | 150 
Rivermead Rd #235
www.pwpconsult.com | perimeter. | 
Peterborough, NH 03458


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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread N4ZR 
Gee Jim, I didn't think I was *that* stupid. Yes, I didn't get the 
decimal places right -that was a simple brain phart.  As for the 
licensing tests, did you have to draw a Colpitts oscillator?  IIRC, that 
was on my General exam in 1955.


With the power strip, what's wrong with measuring the voltage in and 
out, knowing the current being drawn, and deriving the resistance from 
that?


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 4/26/2020 6:24 PM, Jim Brown wrote:
I wouldn't expect useful accuracy from anything but a lab instrument 
for such low resistances as a few feet of #12. Far better to look up 
the resistance of copper wire from a wire table. An unknown "black 
box" like a power strip is not so easy. :) As for the protection 
diode, that's pretty easy too -- look up the junction voltage for that 
type of diode, and you're within 0.1 volt of reality.


The thing I find baffling (or depressing) here is that we all had to 
understand Ohm's Law to pass the exam for our license, and it's REAL 
simple.  Take resistance values from a wire table, multiply by the 
length, then by two for the two conductors, then by the current. I 
dunno what the exam is like nowadays -- my experience was 1955 with 
the Novice test and a year later with the General -- but surely there 
must be something about how diodes work!


73, Jim K9YC


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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Jim Brown 
I wouldn't expect useful accuracy from anything but a lab instrument for 
such low resistances as a few feet of #12. Far better to look up the 
resistance of copper wire from a wire table. An unknown "black box" like 
a power strip is not so easy. :) As for the protection diode, that's 
pretty easy too -- look up the junction voltage for that type of diode, 
and you're within 0.1 volt of reality.


The thing I find baffling (or depressing) here is that we all had to 
understand Ohm's Law to pass the exam for our license, and it's REAL 
simple.  Take resistance values from a wire table, multiply by the 
length, then by two for the two conductors, then by the current. I dunno 
what the exam is like nowadays -- my experience was 1955 with the Novice 
test and a year later with the General -- but surely there must be 
something about how diodes work!


73, Jim K9YC


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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread N4ZR 
Thanks, Bob - I had forgotten about being able to measure at the acc 12v 
output.  In any case, though, the front-panel display provides a pretty 
good number.  It says that the RX-only voltage at the K3 is 13.7 volts.  
My worst-case at 100 watts key down is 12.6 - I don't know where the 11 
volts came from.  As someone suggested, it could be as simple as my 
having plugged and unplugged the various powerpoles a few times.


But here's the real bottom line - depending on band, I only need at most 
40 watts to drive my KPA-1500 to full output.  At that level, voltage 
only drops to 13.1, which is plenty good enough.


Thanks everyone for putting up with me - at least, I'm leaving this 
exercise a little smarter than I went in...



73, Pete N4ZR
Check out the Reverse Beacon Network
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On 4/26/2020 12:32 PM, Bob McGraw K4TAX wrote:
Oh well, I need another cup of coffee.    I'll try to do better proof 
reading.  Can't blame that one on auto-correct!


Cutting to the chase., measure from the power supply POS 
terminal to the ACC 12V on the K3 radio.    That is the total voltage 
drop in the POS DC path.  Then do the same for the NEG terminal of the 
power supply to the ground terminal on the radio. That is the voltage 
drop on the NEG DC path.  Add those two together and one has the total 
voltage drop.  Now, step by step, isolate where each amount of voltage 
drop occurs.


Anytime over 0.5 volts total voltage drop occurs, something needs 
attention.   Thus DC Pos should be less than 0.25 volt drop and DC Neg 
should be less than 0.25 volts.  For a total of 0.5 volts drop at the 
radio.


73

Bob, K4TAX


On 4/26/2020 11:22 AM, Adrian wrote:

I got a good chuckle out of that one Bob, happens to me often


take 2 >
The calculation is simple:    E = I x R  current multiplied by 
resistance equals the voltage.





The calculation is simple:    E = I x R  current multiplied by 
amps equal voltage.


73

Bob, K4TAX






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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Bob McGraw K4TAX 
Pete:  Sorry I read some of your numbers incorrectly.  A cable with 0.3 
ohms resistance and 20 amps of current will have a voltage drop of 20 x 
0.3 for 6 volts.  This can't be correct. More like 20 x 0.03 for 1.2 
volts.   Still too much.


Don't try to measure resistance with a DVM, as point contact and lead 
resistance will be too great.  Just measure voltage drop across the 
various components which will be more accurate. That's what is important 
anyway.


73

Bob, K4TAX


On 4/26/2020 11:34 AM, N4ZR wrote:
Aside from  my decimal point problems  The cable measured 0.3 
ohms, with my DMM, but in retrospect, its measurement could not have 
been correct. However, the measurement on the 4005i is about right, 
because that was done by comparing the voltages at its input and 
output, and was at 100 watts key-down. The 4005i's *voltage drop* at 
100 watts was 0.08 *volts*, which strikes me as not bad at all.


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 4/26/2020 12:11 PM, Bob McGraw K4TAX wrote:
The power cable at 0.03 ohms on each side,  a total of 0.06 ohms 
resistance.  The 4005i, per his measurements, has 0.08 ohms 
resistance.   The power distribution strip contributes more than 50% 
of the voltage drop.   Actually more than the power cables.


The power cable contributes  1.2 volts of drop.   The 4005i 
contributes an added 1.6 volts of drop for a total of 2.8 volts.


The calculation is simple:    E = I x R  current multiplied by 
amps equal voltage.


73

Bob, K4TAX



On 4/26/2020 10:53 AM, Leroy Buller wrote:

40 inches of power cable.  In my experiences,  that could be an issue
depending on the gauge of the wire.  I used a long cable 12 gauge 
and had
issues.  Went to 24 inches number 10 gauge and voltage drop 
significantly
improved.  The resustace does not have to be large to cause a 
voltage  drop


Lee

On Sun, Apr 26, 2020, 9:47 AM N4ZR  wrote:


I've had an e-mail exchange with West Mountain Radio.  Measured the
voltage drop inside the 4005i at only .08 volts at 100 watts key down.
My power cable from the 4500i to the K3 measures 0.3 ohms on each
conductor, which at 20 amps should only yield a 1.2 volt drop, 
right?  I

don't know where the other volt plus of drop is coming from. The cable
is 40 inches long, and only minor shortening is possible. It is about
the largest wire that will fit in the Powerpoles on both the K3 and 
the

4005i.

Suggestions welcome

--
73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread N4ZR 
Aside from  my decimal point problems  The cable measured 0.3 ohms, 
with my DMM, but in retrospect, its measurement could not have been 
correct. However, the measurement on the 4005i is about right, because 
that was done by comparing the voltages at its input and output, and was 
at 100 watts key-down. The 4005i's *voltage drop* at 100 watts was 0.08 
*volts*, which strikes me as not bad at all.


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 4/26/2020 12:11 PM, Bob McGraw K4TAX wrote:
The power cable at 0.03 ohms on each side,  a total of 0.06 ohms 
resistance.  The 4005i, per his measurements, has 0.08 ohms 
resistance.   The power distribution strip contributes more than 50% 
of the voltage drop.   Actually more than the power cables.


The power cable contributes  1.2 volts of drop.   The 4005i 
contributes an added 1.6 volts of drop for a total of 2.8 volts.


The calculation is simple:    E = I x R  current multiplied by 
amps equal voltage.


73

Bob, K4TAX



On 4/26/2020 10:53 AM, Leroy Buller wrote:

40 inches of power cable.  In my experiences,  that could be an issue
depending on the gauge of the wire.  I used a long cable 12 gauge and 
had
issues.  Went to 24 inches number 10 gauge and voltage drop 
significantly
improved.  The resustace does not have to be large to cause a 
voltage  drop


Lee

On Sun, Apr 26, 2020, 9:47 AM N4ZR  wrote:


I've had an e-mail exchange with West Mountain Radio.  Measured the
voltage drop inside the 4005i at only .08 volts at 100 watts key down.
My power cable from the 4500i to the K3 measures 0.3 ohms on each
conductor, which at 20 amps should only yield a 1.2 volt drop, 
right?  I

don't know where the other volt plus of drop is coming from. The cable
is 40 inches long, and only minor shortening is possible.  It is about
the largest wire that will fit in the Powerpoles on both the K3 and the
4005i.

Suggestions welcome

--
73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Bob McGraw K4TAX 
Oh well, I need another cup of coffee.    I'll try to do better proof 
reading.  Can't blame that one on auto-correct!


Cutting to the chase., measure from the power supply POS 
terminal to the ACC 12V on the K3 radio.    That is the total voltage 
drop in the POS DC path.  Then do the same for the NEG terminal of the 
power supply to the ground terminal on the radio. That is the voltage 
drop on the NEG DC path.  Add those two together and one has the total 
voltage drop.  Now, step by step, isolate where each amount of voltage 
drop occurs.


Anytime over 0.5 volts total voltage drop occurs, something needs 
attention.   Thus DC Pos should be less than 0.25 volt drop and DC Neg 
should be less than 0.25 volts.  For a total of 0.5 volts drop at the 
radio.


73

Bob, K4TAX


On 4/26/2020 11:22 AM, Adrian wrote:

I got a good chuckle out of that one Bob, happens to me often


take 2 >
The calculation is simple:    E = I x R  current multiplied by 
resistance equals the voltage.





The calculation is simple:    E = I x R  current multiplied by 
amps equal voltage.


73

Bob, K4TAX






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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Gmail - George 
A couple of solutions used in TV Broadcasting, especially in ENG & Satellite 
mobile units.

1) Use a short jumper from the large conductor the the connector. I solder 
the 2 wires together (inline) and cover the connection with shrink tubing.
This helps when you want flexibility between the large connector and the 
equipment (think mobile vibration).
2)If the large conductor is stranded then remove strands until it fits the 
connector.

Another solutions would be to keep what you have and remote the power supply 
sense to the destination.
The advantage of this solution is that you have a large voltage swing with a 
varying load.
The disadvantage is the power supply has to be capable of supplying all the 
current needed at maximum load and the time constant has to be considerable 
shorter than the load variation time constant.
Another disadvantage is that any other equipment on the power supply line 
will "see" a varying power supply.
This solution is used in many different pieces of equipment in broadcasting.

73
George AI4VZ

-Original Message- 
From: David Herring
Sent: Sunday, April 26, 2020 11:08 AM
To: N4ZR
Cc: Elecraft List
Subject: Re: [Elecraft] Voltage drop in DX Power to K3

I’m late in coming to this thread, so sorry if I missed the answer to this 
question, but what is the voltage drop between the power supply and the 
4005i?

73, David N5DCH

> On Apr 26, 2020, at 8:46 AM, N4ZR  wrote:
>
> I've had an e-mail exchange with West Mountain Radio.  Measured the 
> voltage drop inside the 4005i at only .08 volts at 100 watts key down.  My 
> power cable from the 4500i to the K3 measures 0.3 ohms on each conductor, 
> which at 20 amps should only yield a 1.2 volt drop, right?  I don't know 
> where the other volt plus of drop is coming from.  The cable is 40 inches 
> long, and only minor shortening is possible.  It is about the largest wire 
> that will fit in the Powerpoles on both the K3 and the 4005i.
>
> Suggestions welcome
>
> -- 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> __
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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Jack Brindle via Elecraft 
There is one more item that has been forgotten. The K3 has an SB530 Schottky 
diode in the power input circuit between the input fuse and the main 12V bus 
(but not the 100 watt 12V PA bus). This will account for about a half of a volt 
drop. If you are using the front panel voltage reading, this must be added into 
the equation. In other words, the voltage at the power pole is about a half 
volt higher than the front panel reading.

It might be worth while to take a look at the schematics for the K3 - they are 
available at the Elecraft web site.

Now back to the discussion…

73!
Jack, W6FB
ps.  DX Power?

> On Apr 26, 2020, at 9:11 AM, Bob McGraw K4TAX  wrote:
> 
> The power cable at 0.03 ohms on each side,  a total of 0.06 ohms resistance.  
> The 4005i, per his measurements, has 0.08 ohms resistance.   The power 
> distribution strip contributes more than 50% of the voltage drop.   Actually 
> more than the power cables.
> 
> The power cable contributes  1.2 volts of drop.   The 4005i contributes an 
> added 1.6 volts of drop for a total of 2.8 volts.
> 
> The calculation is simple:E = I x R  current multiplied by amps equal 
> voltage.
> 
> 73
> 
> Bob, K4TAX
> 
> 
> 
> On 4/26/2020 10:53 AM, Leroy Buller wrote:
>> 40 inches of power cable.  In my experiences,  that could be an issue
>> depending on the gauge of the wire.  I used a long cable 12 gauge and had
>> issues.  Went to 24 inches number 10 gauge and voltage drop significantly
>> improved.  The resustace does not have to be large to cause a voltage  drop
>> 
>> Lee
>> 
>> On Sun, Apr 26, 2020, 9:47 AM N4ZR  wrote:
>> 
>>> I've had an e-mail exchange with West Mountain Radio.  Measured the
>>> voltage drop inside the 4005i at only .08 volts at 100 watts key down.
>>> My power cable from the 4500i to the K3 measures 0.3 ohms on each
>>> conductor, which at 20 amps should only yield a 1.2 volt drop, right?  I
>>> don't know where the other volt plus of drop is coming from.  The cable
>>> is 40 inches long, and only minor shortening is possible.  It is about
>>> the largest wire that will fit in the Powerpoles on both the K3 and the
>>> 4005i.
>>> 
>>> Suggestions welcome
>>> 
>>> --
>>> 73, Pete N4ZR
>>> Check out the Reverse Beacon Network
>>> at , now
>>> spotting RTTY activity worldwide.
>>> For spots, please use your favorite
>>> "retail" DX cluster.
>>> 
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[email protected]
>>> 
>>> This list hosted by: http://www.qsl.net
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>>> Message delivered to [email protected]
>> __
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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Adrian 

I got a good chuckle out of that one Bob, happens to me often


take 2 >
The calculation is simple:    E = I x R  current multiplied by 
resistance equals the voltage.





The calculation is simple:    E = I x R  current multiplied by 
amps equal voltage.


73

Bob, K4TAX



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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread N4ZR 

Approximately .3 volts with a cable about a foot long.

73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 4/26/2020 11:08 AM, David Herring wrote:

I’m late in coming to this thread, so sorry if I missed the answer to this 
question, but what is the voltage drop between the power supply and the 4005i?

73, David N5DCH


On Apr 26, 2020, at 8:46 AM, N4ZR  wrote:

I've had an e-mail exchange with West Mountain Radio.  Measured the voltage 
drop inside the 4005i at only .08 volts at 100 watts key down.  My power cable 
from the 4500i to the K3 measures 0.3 ohms on each conductor, which at 20 amps 
should only yield a 1.2 volt drop, right?  I don't know where the other volt 
plus of drop is coming from.  The cable is 40 inches long, and only minor 
shortening is possible.  It is about the largest wire that will fit in the 
Powerpoles on both the K3 and the 4005i.

Suggestions welcome

--
73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Bob McGraw K4TAX 
The power cable at 0.03 ohms on each side,  a total of 0.06 ohms 
resistance.  The 4005i, per his measurements, has 0.08 ohms 
resistance.   The power distribution strip contributes more than 50% of 
the voltage drop.   Actually more than the power cables.


The power cable contributes  1.2 volts of drop.   The 4005i contributes 
an added 1.6 volts of drop for a total of 2.8 volts.


The calculation is simple:    E = I x R  current multiplied by amps 
equal voltage.


73

Bob, K4TAX



On 4/26/2020 10:53 AM, Leroy Buller wrote:

40 inches of power cable.  In my experiences,  that could be an issue
depending on the gauge of the wire.  I used a long cable 12 gauge and had
issues.  Went to 24 inches number 10 gauge and voltage drop significantly
improved.  The resustace does not have to be large to cause a voltage  drop

Lee

On Sun, Apr 26, 2020, 9:47 AM N4ZR  wrote:


I've had an e-mail exchange with West Mountain Radio.  Measured the
voltage drop inside the 4005i at only .08 volts at 100 watts key down.
My power cable from the 4500i to the K3 measures 0.3 ohms on each
conductor, which at 20 amps should only yield a 1.2 volt drop, right?  I
don't know where the other volt plus of drop is coming from.  The cable
is 40 inches long, and only minor shortening is possible.  It is about
the largest wire that will fit in the Powerpoles on both the K3 and the
4005i.

Suggestions welcome

--
73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

__
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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread Leroy Buller 
40 inches of power cable.  In my experiences,  that could be an issue
depending on the gauge of the wire.  I used a long cable 12 gauge and had
issues.  Went to 24 inches number 10 gauge and voltage drop significantly
improved.  The resustace does not have to be large to cause a voltage  drop

Lee

On Sun, Apr 26, 2020, 9:47 AM N4ZR  wrote:

> I've had an e-mail exchange with West Mountain Radio.  Measured the
> voltage drop inside the 4005i at only .08 volts at 100 watts key down.
> My power cable from the 4500i to the K3 measures 0.3 ohms on each
> conductor, which at 20 amps should only yield a 1.2 volt drop, right?  I
> don't know where the other volt plus of drop is coming from.  The cable
> is 40 inches long, and only minor shortening is possible.  It is about
> the largest wire that will fit in the Powerpoles on both the K3 and the
> 4005i.
>
> Suggestions welcome
>
> --
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[email protected]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [email protected]
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Re: [Elecraft] Voltage drop in DX Power to K3

2020-04-26 Thread David Herring 
I’m late in coming to this thread, so sorry if I missed the answer to this 
question, but what is the voltage drop between the power supply and the 4005i? 

73, David N5DCH

> On Apr 26, 2020, at 8:46 AM, N4ZR  wrote:
> 
> I've had an e-mail exchange with West Mountain Radio.  Measured the voltage 
> drop inside the 4005i at only .08 volts at 100 watts key down.  My power 
> cable from the 4500i to the K3 measures 0.3 ohms on each conductor, which at 
> 20 amps should only yield a 1.2 volt drop, right?  I don't know where the 
> other volt plus of drop is coming from.  The cable is 40 inches long, and 
> only minor shortening is possible.  It is about the largest wire that will 
> fit in the Powerpoles on both the K3 and the 4005i.
> 
> Suggestions welcome
> 
> -- 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[email protected]
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [email protected]

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