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K3 Voltage on TX

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Rich-4

K3 Voltage on TX

Folks,

I am not sure if I have some sort of issues or not. My K3 shows 13.7VDC
on RX. When I TX that reading drops to 10.9VDC. Is that a normal drop?
I do not believe this is a K3 issue, but I was wondering if others see
that much drop before I dig into my 12VDC supply system.

Thanks
Rich
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Jim Brown-10

Re: K3 Voltage on TX

On Mon,10/26/2015 8:48 AM, Rich wrote:
> My K3 shows 13.7VDC on RX. When I TX that reading drops to 10.9VDC. Is
> that a normal drop?

It's not good. Two possible reasons -- poor regulation of the power
supply and IR drop in the power cable.

How long is the power cable between the K3 and power supply? What wire
gauge? Do the arithmetic for Ohm's law for the IR drop in that length
of that wire gauge. and remember to use the length of the cable x2 (for
two conductors). Resistance per ft for various wire gauges is in the
ARRL Handbook.

Put a voltmeter across the output terminals of the power supply and
check the voltage. It's also possible that the power supply has poor
regulation.

73, Jim K9YC

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Don Wilhelm-4

Re: K3 Voltage on TX

In reply to this post by Rich-4

Rich,

Yes, that is abnormal.
Either your power supply is sagging or there is too much voltage drop in
the power cable.
To figure out which it is, measure the power supply voltage at its
terminals during transmit. If it is staying "right up there" as it
should, then the problem is in the cable. Check that the power supply
terminals are tight, check that the fuseholders have good contact with
the fuses (change the fuse(s) because they can develop a higher than
normal resistance. Make certain that the APP connector on the K3 end of
the cable has its contacts fully inserted - the tip of the connector
blade should be latched over the spring finger below it. If you can see
both the spring finger and the tip of the contact blade when you look
from the front, the contact blade is not fully inserted.

73,
Don W3FPR

On 10/26/2015 11:48 AM, Rich wrote:

> Folks,
>
> I am not sure if I have some sort of issues or not. My K3 shows
> 13.7VDC on RX. When I TX that reading drops to 10.9VDC. Is that a
> normal drop? I do not believe this is a K3 issue, but I was wondering
> if others see that much drop before I dig into my 12VDC supply system.
>
> Thanks
> Rich
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Phil Wheeler-2

Re: K3 Voltage on TX

In reply to this post by Jim Brown-10

If the wire gauge is OK and the supply regulation
is not at fault, give some attention to the
connectors at each end of the cable, too. A drop
of 2.8 Volts points to some sort of issue.

73, Phil W7OX

On 10/26/15 9:02 AM, Jim Brown wrote:

> On Mon,10/26/2015 8:48 AM, Rich wrote:
>> My K3 shows 13.7VDC on RX. When I TX that
>> reading drops to 10.9VDC. Is that a normal drop?
>
> It's not good. Two possible reasons -- poor
> regulation of the power supply and IR drop in
> the power cable.
>
> How long is the power cable between the K3 and
> power supply? What wire gauge? Do the
> arithmetic for Ohm's law for the IR drop in that
> length of that wire gauge. and remember to use
> the length of the cable x2 (for two conductors).
> Resistance per ft for various wire gauges is in
> the ARRL Handbook.
>
> Put a voltmeter across the output terminals of
> the power supply and check the voltage. It's
> also possible that the power supply has poor
> regulation.
>
> 73, Jim K9YC

Rich-4

Re: K3 Voltage on TX

Thanks to all. I have check my PS and it does not fluctuate even a
tenth of a volt on TX. With the radio connected directly to the PS.
I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer
at the wire gauge and connectors. That is still about 2VDC drop.

Thanks for the help

rich

On 10/26/2015 12:09 PM, Phil Wheeler wrote:

> If the wire gauge is OK and the supply regulation is not at fault,
> give some attention to the connectors at each end of the cable, too. A
> drop of 2.8 Volts points to some sort of issue.
>
> 73, Phil W7OX
>
> On 10/26/15 9:02 AM, Jim Brown wrote:
>> On Mon,10/26/2015 8:48 AM, Rich wrote:
>>> My K3 shows 13.7VDC on RX. When I TX that reading drops to 10.9VDC.
>>> Is that a normal drop?
>>
>> It's not good. Two possible reasons -- poor regulation of the power
>> supply and IR drop in the power cable.
>>
>> How long is the power cable between the K3 and power supply? What
>> wire gauge? Do the arithmetic for Ohm's law for the IR drop in that
>> length of that wire gauge. and remember to use the length of the
>> cable x2 (for two conductors). Resistance per ft for various wire
>> gauges is in the ARRL Handbook.
>>
>> Put a voltmeter across the output terminals of the power supply and
>> check the voltage. It's also possible that the power supply has poor
>> regulation.
>>
>> 73, Jim K9YC
>
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k6dgw

Re: K3 Voltage on TX

In reply to this post by Rich-4

That's way more drop than I experience with a 4S1P LiFePO4. Things to
check:

Length and gauge of wire [remember to double the length when calculating
resistance, it's a round trip for the electrons].

Poor regulation in the power supply or depleted battery or battery at
the end of useful life.

Voltage drop at connectors

Voltage drop at fuses.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

On 10/26/2015 8:48 AM, Rich wrote:

> I am not sure if I have some sort of issues or not. My K3 shows 13.7VDC
> on RX. When I TX that reading drops to 10.9VDC. Is that a normal drop?
> I do not believe this is a K3 issue, but I was wondering if others see
> that much drop before I dig into my 12VDC supply system.

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k6dgw

Re: K3 Voltage on TX

In reply to this post by Rich-4

That's still too much. Last time I measured my K3, the drop was 0.6 V
on TX at 100W. Cartridge type [AGC] fuses and the holders are common
culprits. I've replaced all of my fuses with the automotive fuses with
the blade type contacts. They present a large contact area, are very
tight, and have a large wipe as you insert and remove them.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

On 10/26/2015 10:05 AM, Rich wrote:
> Thanks to all. I have check my PS and it does not fluctuate even a
> tenth of a volt on TX. With the radio connected directly to the PS. I
> am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer at
> the wire gauge and connectors. That is still about 2VDC drop.

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Fred Townsend-2

Re: K3 Voltage on TX

In reply to this post by Rich-4

Hi Rich:
A couple of more things. First do the math. Assuming 20 amps of transmit
current (that's my rig @100 watts output) with a 2 volt drop is 40 watts of
lost energy (not my rig). That also happens to be the power rating of my
soldering iron. To point, something is likely to be getting warm. You should
be able to find your problem by touching your cables and connectors while
transmitting a 100 watts of RTTY, AM, etc.
Also, I hope you are not using a diode type power sharing device sold to
share power supply and battery. Think about it. Why do they need a big heat
sink? Big heat sinks mean lots of wasted power.
73
Fred, AE6QL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Rich
Sent: Monday, October 26, 2015 10:05 AM
To: [hidden email]
Subject: Re: [Elecraft] K3 Voltage on TX

Thanks to all. I have check my PS and it does not fluctuate even a
tenth of a volt on TX. With the radio connected directly to the PS.
I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer at
the wire gauge and connectors. That is still about 2VDC drop.

Thanks for the help

rich

On 10/26/2015 12:09 PM, Phil Wheeler wrote:

> If the wire gauge is OK and the supply regulation is not at fault,
> give some attention to the connectors at each end of the cable, too. A
> drop of 2.8 Volts points to some sort of issue.
>
> 73, Phil W7OX
>
> On 10/26/15 9:02 AM, Jim Brown wrote:
>> On Mon,10/26/2015 8:48 AM, Rich wrote:
>>> My K3 shows 13.7VDC on RX. When I TX that reading drops to 10.9VDC.
>>> Is that a normal drop?
>>
>> It's not good. Two possible reasons -- poor regulation of the power
>> supply and IR drop in the power cable.
>>
>> How long is the power cable between the K3 and power supply? What
>> wire gauge? Do the arithmetic for Ohm's law for the IR drop in that
>> length of that wire gauge. and remember to use the length of the
>> cable x2 (for two conductors). Resistance per ft for various wire
>> gauges is in the ARRL Handbook.
>>
>> Put a voltmeter across the output terminals of the power supply and
>> check the voltage. It's also possible that the power supply has poor
>> regulation.
>>
>> 73, Jim K9YC
>
> ______________________________________________________________
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> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
>

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Bob McGraw - K4TAX

Re: K3 Voltage on TX

In reply to this post by Rich-4

You don't happen to have anything else in line between the power supply
and the K3 do you? I've found those DC distribution panels sold by
certain companies are contributors to significant voltage drop. Your
statement " With the radio connected directly to the PS. I am now
seeing 14.1 VDC and 12.0 VDC on TX." is a clue that the way you have
things configured is not optimum. In fact, anything in line between
the power supply and radio can contribute to this. Even fuses,
switches, power connectors and such. Any connection that is loose or
terminal that is loose will be a voltage drop point. They just add up.

My rule: the radio connects direct to the power supply. No exception.
If you need DC for something else, connect it direct to the power supply
as well. I also use a dedicated ground conductor between the radio and
DC supply ground. The DC Negative is not considered to be adequate ground.

73
Bob, K4TAX
K3S s/n 10163

On 10/26/2015 12:05 PM, Rich wrote:

> Thanks to all. I have check my PS and it does not fluctuate even a
> tenth of a volt on TX. With the radio connected directly to the PS.
> I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer
> at the wire gauge and connectors. That is still about 2VDC drop.
>
> Thanks for the help
>
> rich
>
> On 10/26/2015 12:09 PM, Phil Wheeler wrote:
>> If the wire gauge is OK and the supply regulation is not at fault,
>> give some attention to the connectors at each end of the cable, too.
>> A drop of 2.8 Volts points to some sort of issue.
>>
>> 73, Phil W7OX

Bob McGraw - K4TAX

Re: K3 Voltage on TX

I just checked my radio. Receive shows 13.7 volts. At 100 watts CW key
down transmit it shows 13.3 volts. The current indicated on the power
supply is 18 amps. Power leads are about 2 ft in length being #10
stranded with connectors crimped and soldered at both ends. Also a #10
AWG ground is in place between the radio and power supply

73
Bob, K4TAX
K3S s/n 10163

On 10/26/2015 2:37 PM, Bob McGraw - K4TAX wrote:

> You don't happen to have anything else in line between the power
> supply and the K3 do you? I've found those DC distribution panels
> sold by certain companies are contributors to significant voltage
> drop. Your statement " With the radio connected directly to the PS.
> I am now seeing 14.1 VDC and 12.0 VDC on TX." is a clue that the way
> you have things configured is not optimum. In fact, anything in
> line between the power supply and radio can contribute to this. Even
> fuses, switches, power connectors and such. Any connection that is
> loose or terminal that is loose will be a voltage drop point. They
> just add up.
>
> My rule: the radio connects direct to the power supply. No
> exception. If you need DC for something else, connect it direct to
> the power supply as well. I also use a dedicated ground conductor
> between the radio and DC supply ground. The DC Negative is not
> considered to be adequate ground.
>
> 73
> Bob, K4TAX
> K3S s/n 10163
>
>
>
> On 10/26/2015 12:05 PM, Rich wrote:
>> Thanks to all. I have check my PS and it does not fluctuate even a
>> tenth of a volt on TX. With the radio connected directly to the
>> PS. I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look
>> closer at the wire gauge and connectors. That is still about 2VDC drop.
>>
>> Thanks for the help
>>
>> rich

Jim Brown-10

Re: K3 Voltage on TX

In reply to this post by Bob McGraw - K4TAX

On Mon,10/26/2015 12:37 PM, Bob McGraw - K4TAX wrote:
> In fact, anything in line between the power supply and radio can
> contribute to this. Even fuses, switches, power connectors and such.
> Any connection that is loose or terminal that is loose will be a
> voltage drop point. They just add up.

Yes. I've been told that the DC bus in popular DC distribution strips is
quite small considering the rated current. They're fine for accessories
that don't draw much current, but don't run your rig through them
(unless it's QRP)!

73, Jim K9YC
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Bill Frantz

Re: K3 Voltage on TX

I gave up running my K3 through a RigRunner for just that
reason. I put in a short lead directly to the battery bank APP
junction strip and things got a lot better. They got even better
with a N8XJK Boost Regulator between the K3 and the junction.
(Tested with 100W into a dummy load.)

73 Bill AE6JV

On 10/26/15 at 12:50 PM, [hidden email] (Jim Brown) wrote:

>On Mon,10/26/2015 12:37 PM, Bob McGraw - K4TAX wrote:
>>In fact, anything in line between the power supply and radio
>>can contribute to this. Even fuses, switches, power
>>connectors and such. Any connection that is loose or terminal
>>that is loose will be a voltage drop point. They just add up.
>
>Yes. I've been told that the DC bus in popular DC distribution
>strips is quite small considering the rated current. They're
>fine for accessories that don't draw much current, but don't
>run your rig through them (unless it's QRP)!

-----------------------------------------------------------------------
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(408)356-8506 | ads, you are the product. | 16345
Englewood Ave
www.pwpconsult.com | | Los Gatos,
CA 95032

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Jim AB3CV

Re: K3 Voltage on TX

I was having too much drop with RR as well. I switched to a 1ft line
directly to my Samlex 1235M which has been jacked to 14.4v no load. It only
moves a few mV when loaded to 20A.

IIRC, the cable is now AWG12.

jim ab3cv
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Jim AB3CV

Re: K3 Voltage on TX

Forgot to mention: the RR runs everything else that needs 14v.

On Mon, Oct 26, 2015 at 5:08 PM, Jim Miller <[hidden email]> wrote:

> I was having too much drop with RR as well. I switched to a 1ft line
> directly to my Samlex 1235M which has been jacked to 14.4v no load. It only
> moves a few mV when loaded to 20A.
>
> IIRC, the cable is now AWG12.
>
> jim ab3cv
>
>
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Bob McGraw - K4TAX

Re: K3 Voltage on TX

In reply to this post by Bill Frantz

Well my take.....ANYTHING between the power source and radio has
resistance, regardless of how small. Resistance with any amount of
current equals voltage drop. Thus E = IR Where E is the voltage drop,
I is the current and R is the resistance.

I'm not sure what some of those thing are nor why they are needed but I
do know least is best. As to operating from batteries, floating AGM
batteries at 13.8 should not produce any voltage drop other than the
resistance of the power cable. Of course a fuse or switch in line
does have R so there goes the regulation as current changes. Nothing is
better than a good regulated supply and hopefully one with remote
voltage sensing. Of course those are more expensive and more of a
challenge to install and then have operate correctly in the presence of
a RF field.

73
Bob, K4TAX
K3S s.n. 10163

On 10/26/2015 3:55 PM, Bill Frantz wrote:

> I gave up running my K3 through a RigRunner for just that reason. I
> put in a short lead directly to the battery bank APP junction strip
> and things got a lot better. They got even better with a N8XJK Boost
> Regulator between the K3 and the junction. (Tested with 100W into a
> dummy load.)
>
> 73 Bill AE6JV
>
> On 10/26/15 at 12:50 PM, [hidden email] (Jim Brown) wrote:
>
>> On Mon,10/26/2015 12:37 PM, Bob McGraw - K4TAX wrote:
>>> In fact, anything in line between the power supply and radio can
>>> contribute to this. Even fuses, switches, power connectors and
>>> such. Any connection that is loose or terminal that is loose will
>>> be a voltage drop point. They just add up.
>>
>> Yes. I've been told that the DC bus in popular DC distribution strips
>> is quite small considering the rated current. They're fine for
>> accessories that don't draw much current, but don't run your rig
>> through them (unless it's QRP)!

Bill Frantz

Re: K3 Voltage on TX

Perhaps it's vanity, but I like running my rig off solar power
and batteries. Since I also take the rig out in the field
somewhat frequently, battery power avoids noisy generators.
(Besides, I own the panels and batteries, but don't own a generator.)

In any case, floating batteries requires a power source during
operations which doesn't work really well with solar power at
night. The WVARA operation discovered during the last California
QSO Party that tired batteries and K3s are a recipe for
transmitter distortion and local interference in a multi-radio
operation. The N8XJK Battery Booster is an attempt to get more
life from tired batteries into the just before dawn hours.

73 Bill AE6JV

On 10/26/15 at 2:18 PM, [hidden email] (Bob McGraw - K4TAX) wrote:

>Well my take.....ANYTHING between the power source and radio
>has resistance, regardless of how small. Resistance with any
>amount of current equals voltage drop. Thus E = IR Where E
>is the voltage drop, I is the current and R is the resistance.
>
>I'm not sure what some of those thing are nor why they are
>needed but I do know least is best. As to operating from
>batteries, floating AGM batteries at 13.8 should not produce
>any voltage drop other than the resistance of the power
>cable. Of course a fuse or switch in line does have R so
>there goes the regulation as current changes. Nothing is
>better than a good regulated supply and hopefully one with
>remote voltage sensing. Of course those are more expensive
>and more of a challenge to install and then have operate
>correctly in the presence of a RF field.
>
>73
>Bob, K4TAX
>K3S s.n. 10163
>
>On 10/26/2015 3:55 PM, Bill Frantz wrote:
>>I gave up running my K3 through a RigRunner for just that
>>reason. I put in a short lead directly to the battery bank APP
>>junction strip and things got a lot better. They got even
>>better with a N8XJK Boost Regulator between the K3 and the
>>junction. (Tested with 100W into a dummy load.)
>>
>>73 Bill AE6JV

Richard Fjeld-2

Re: K3 Voltage on TX

In reply to this post by Rich-4

It would be nice to have test point type jacks on the back of the K3 to
test the voltage drop from the PS through the APP's entering the K3.
This would check the accuracy of the K3 volt-meter as well. I don't
remember what it looks like in the vicinity of the APP's.

The next best thing we have is the 12V jack, but I think that has two
diodes in series to it.

Dick, n0ce

On 10/26/2015 12:05 PM, Rich wrote:
> Thanks to all. I have check my PS and it does not fluctuate even a
> tenth of a volt on TX. With the radio connected directly to the PS.
> I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer
> at the wire gauge and connectors. That is still about 2VDC drop.
>
> Thanks for the help
>
> rich
>

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Gary Gregory-2

Re: K3 Voltage on TX

This discussion has got me confused.
If a power supply fails, it is pretty easy to fault find.
If you use the correct size cable for the length you require, then it WILL work.
Discussions on APP and test points seem to me to be a little pedantic as apart from from a power supply failure I have not had voltage drop issues other than killing a large battery bank while exuberantly working a field day operation some years ago. I blame Eric for chatting to me too long on that occasion....😊
From memory the only other fault I have seen was a disconnected APP on the board. The owner told me had no idea how that came about. I re-soldered the connection and the K3 came back to life.
Caveat emptor......i have always used a heavier DC power lead.

Gary

-----Original Message-----
From: "Richard Fjeld" <[hidden email]>
Sent: ‎27/‎10/‎2015 9:30 AM
To: "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] K3 Voltage on TX

It would be nice to have test point type jacks on the back of the K3 to
test the voltage drop from the PS through the APP's entering the K3.
This would check the accuracy of the K3 volt-meter as well. I don't
remember what it looks like in the vicinity of the APP's.

The next best thing we have is the 12V jack, but I think that has two
diodes in series to it.

Dick, n0ce

On 10/26/2015 12:05 PM, Rich wrote:
> Thanks to all. I have check my PS and it does not fluctuate even a
> tenth of a volt on TX. With the radio connected directly to the PS.
> I am now seeing 14.1 VDC and 12.0 VDC on TX. So I need to look closer
> at the wire gauge and connectors. That is still about 2VDC drop.
>
> Thanks for the help
>
> rich
>

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Mike Maloney

Re: K3 Voltage on TX

In reply to this post by Bill Frantz

If voltage is being checked via the K3 display, I believe there is a series diode before the internal metering that adds a 0.6V drop in TX?
73, Mike AC5P

On Monday, October 26, 2015 5:08 PM, Bill Frantz <[hidden email]> wrote:

Perhaps it's vanity, but I like running my rig off solar power
and batteries. Since I also take the rig out in the field
somewhat frequently, battery power avoids noisy generators.
(Besides, I own the panels and batteries, but don't own a generator.)

In any case, floating batteries requires a power source during
operations which doesn't work really well with solar power at
night. The WVARA operation discovered during the last California
QSO Party that tired batteries and K3s are a recipe for
transmitter distortion and local interference in a multi-radio
operation. The N8XJK Battery Booster is an attempt to get more
life from tired batteries into the just before dawn hours.

73 Bill AE6JV

On 10/26/15 at 2:18 PM, [hidden email] (Bob McGraw - K4TAX) wrote:

-----------------------------------------------------------------------
Bill Frantz |The nice thing about standards| Periwinkle
(408)356-8506 |is there are so many to choose| 16345
Englewood Ave
www.pwpconsult.com |from. - Andrew Tanenbaum | Los Gatos,
CA 95032

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Don Wilhelm-4

Re: K3 Voltage on TX

In reply to this post by Richard Fjeld-2

Dick,

If the main interest is the drop in voltage, the 12V jack will work
fine, no matter how many diodes are in series with it.
So you get 10 volts during RX and 9 volts during TX, that is a 1 volt
drop (OK, that is extreme, but hopefully makes the point).
If you are instead looking for the absolute voltage delivered to the K3,
use the VFO B voltage display.

73,
Don W3FPR

On 10/26/2015 7:29 PM, Richard Fjeld wrote:
> It would be nice to have test point type jacks on the back of the K3
> to test the voltage drop from the PS through the APP's entering the K3.
> This would check the accuracy of the K3 volt-meter as well. I don't
> remember what it looks like in the vicinity of the APP's.
>
> The next best thing we have is the 12V jack, but I think that has two
> diodes in series to it.
>

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