Re: [Elecraft] K3 and KX3 questions for Wayne

[Wes]

I can tell you from first hand testing of both a K3 and a K3S, in addition to 
supply voltage, frequency, drive level, load Z and the phase of the moon all 
effect TX IMD. DO NOT assume that just because you have the supply voltage at 
the high end you are done.  DO NOT assume that good IMD on 80-meters means good 
IMD on 10-meters.  ARRL should learn this.


For those with the equipment and inclination, some measurements might be 
illuminating.  The K3(S) makes it fairly easy since a two-tone generator is 
built in.  All that is needed is a spectrum analyzer to look at the output.  I 
happened to use an SDR-IQ and SpectraVue software, but even a second, carefully 
calibrated and operated receiver will suffice.  It will be laborious but 
informative.  (BTW, my measured data correlated within 1 dB, or less, to that 
measured by Elecraft.  You just have to know what you're doing.)


Wes  N7WS


 On 5/23/2016 12:42 AM, Bill Frantz wrote:

An addition to Jim's comments below.

All 100W rigs, regardless of manufacturer, whether the amp is part of the 
radio or a separate unit, develop significant distortion as the voltage drops. 
We noticed the effect at CQP last year. We were operating on batteries as our 
hosts have a no generator rule. As our batteries got lower, our 3 stations -- 
2 K3s and a KX3 with KXPA100 -- started interfering with each other. The 
problem went away when we replaced the batteries with fresh ones.


This distortion will also affect your signal as received by distant stations, 
so it is undesirable in a rig unless you want a reputation for a bad signal.


One way to be able to get maximum runtime from your batteries is to use a 
voltage booster regulator. I use a N8XJK Boost Regulator from TGE. This device 
boosts the battery voltage to the radio. Mine shows 13.9 volts, receive and 
13.4 volts key down at 100W on 160M, even with relatively low batteries. (It 
does have a low voltage cut off to protect the batteries.)


The N8XJK Boost Regulator does generate some minor birdies on receive, so I 
have it set up to only boost voltage when it senses RF output from the 
transmitter.


73 Bill AE6JV


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Re: [Elecraft] K3 and KX3 questions for Wayne

[Edward R Cole]

Mike,

Within 2-3w based on RF ammeter reading of 1.40 amps that match 
I^2*R=100w.  50-MHz 50w and HF-100w Bird elements were within 1w 
agreement at 50w output on 6m.  And long use of the meter on many 
bands with multiple rigs.


Of course Bird rates +/- 5% of full reading which would be +/- 5w but 
then if 72w reading were actually 77w then the amp is outputting 117w 
on 20m.  Also Bird appears to be good agreement with the KVPA-100 Bar 
meter which reads 70 on 6m, and the power meter on my Drake MN2000 
antenna tuner shows same output as the Bird.


Input SWR of the amp is 1.4 on 6m vs 1.0 on HF which may suggest 
something. I am going to swap out coax lines everywhere and 
re-measure.  But I had also assumed the Astron was running 14.2v from 
measurement years ago when installed, so may have shifted down with aging.


72w vs 80w is nitpicking but I had hoped it would show specs on all 
bands considering its cost.  Interesting that 6m takes nearly twice 
the drive power that is needed on HF.  Perhaps the limiting factor is 
the matching transformers.  If so that is a disappointment.


6m band is most demanding with often weak-signal conditions so every 
watt is important.  I traded my 150w Mirage 6m amp to buy the 
KXPA-100 realizing that it was rated at nearly half the output on 
6m.  I plan some improvements to my 6m station this year which will 
compensate: 1) adding a second 6-element yagi, 2) finishing a 1100w 
6m amplifier which can be run at 800w on SSB with 8w drive from my 
KX3.  But the KXPA-100 will likely be used for normal daily use and 
QRO reserved for extreme DX operating (including eme and ms).


If I find the issue was with coax cables I will report that after 
testing.  Also will provide measurements after raising Astron 50A to 14.2v.


73, Ed - KL7UW


How accurate do you believe the Bird to be?

73, Mike NF4L



73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
dubus...@gmail.com

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Re: [Elecraft] K3 and KX3 questions for Wayne

[Jim Brown]

On Mon,5/23/2016 6:36 AM, brian wrote:


1 dB is generally agreed upon to be the minimum detectible difference 
in audio that people can detect.


Of course, these measurements don't include QRM, QSB or AGC action.


Exactly right on both counts. That "generally agreed" is actually the 
result of research done nearly a century ago.


For absolute level (loudness), it takes a change of 6-10 dB to be 
perceived as "twice as loud" or "half as loud." But when the desired 
signal is near the level of noise or other signals, a change of only a 
dB or two can make a BIG difference in whether or not we make the QSO. 
One of the things I did professionally was mix live sound, both for 
sound reinforcement and recording/broadcast. When a given instrument or 
voice needed to be louder to balance well, the needed change was rarely 
more than a dB or two unless I had the mix very wrong to begin with or a 
musician changed something a lot (like moving too far from the mic, or 
playing a different instrument).


So -- when conditions are marginal (on the edge of the other guy's 
noise), every dB matters. That's why the best operators work to optimize 
their antenna systems and squeezing every last dB of loss out of the coax.


73, Jim K9YC


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Re: [Elecraft] K3 and KX3 questions for Wayne

[Mike Reublin NF4L]

How accurate do you believe the Bird to be?

73, Mike NF4L

> On May 23, 2016, at 9:35 AM, Edward R Cole  wrote:
> 
> I am getting 100w on all HF bands with about 4w drive.  Supply voltage is 
> 13.71v in Rx and runs 13.12v with 100w output and 13.07v with 110w output 
> with 5.2w drive (tests on 14-MHz into a Bird Power meter (100H) and Bird 
> Load).
> I compared the reading of the 100H element at 50w on 6m with a 50A element 
> with nearly identical reading.
> 
> But on 6m it takes 7.2w drive and I only see 72w output at 13.15v.  Advancing 
> drive higher engages the auto-ATT, so it would suggest drive is high enough.
> 
> A little disappointed that 6m did not develop output per spec (80w) though I 
> guess no one would note the difference of 72 vs 80.  I am running a 50A 
> Astron PS which indicates 13.71v at the PS terminal  I have not measured what 
> that is under load of the KXPA-100 as PS terminals are difficult to reach.  
> Voltage measured with Fluke model 17B+.
> 
> I may try adjusting the Astron to 14.2v to see if that will improve output; 
> assuming similar 0.6v drop under load would result in 13.6v.
> 
> I substituted a No.10 PP power cord for the No.12 cord provided with the amp 
> with no discernable difference.
> 
> 73, Ed - KL7UW
> http://www.kl7uw.com
>"Kits made by KL7UW"
> Dubus Mag business:
>dubus...@gmail.com
> 
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Re: [Elecraft] K3 and KX3 questions for Wayne

[brian]

Ray,

1 dB is generally agreed upon to be the minimum detectible difference in 
audio that people can detect.


Of course, these measurements don't include QRM, QSB or AGC action.

Big gun stations will kill to pick up 1 or 2 dB extra gain somewhere.

73 de Brian/K3KO


On 5/23/2016 12:46 PM, Ray Sills wrote:

And following up with Jim’s posting about the KXPA100 specs:  At the far end of 
a QSO, the difference between an 80 watt signal vs a 100 watt signal would be 
difficult to measure, let alone perceive by ear.  In most cases, a 6 dB 
difference in level is clearly noticeable, and that would be 25 watts vs 100 
watts.   A 3 dB difference can be heard by most people, but a 1 or 2 dB 
difference is almost impossible to notice by ear.

So, even if you are operating with just 12 V, at the input to the amp… don’t 
sweat it.  If you can’t make the QSO with 80 watts, you aren’t going to make it 
with 100 watts… not on HF, with SSB or CW.

73 de Ray
K2ULR
KX3 #211



On May 22, 2016, at 5:46 PM, Jim Brown  wrote:

On Sun,5/22/2016 11:46 AM, N6MQL wrote:

Although I appreciate all of your answers I specifically asked these questions 
of Wayne because I was making a point to let him know of my disapproval of the 
fact that the KXPA100 amp is incapable of running a full 100 watts on a 
standard 12v battery.




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Re: [Elecraft] K3 and KX3 questions for Wayne

[Edward R Cole]

I am getting 100w on all HF bands with about 4w drive.  Supply 
voltage is 13.71v in Rx and runs 13.12v with 100w output and 13.07v 
with 110w output with 5.2w drive (tests on 14-MHz into a Bird Power 
meter (100H) and Bird Load).
I compared the reading of the 100H element at 50w on 6m with a 50A 
element with nearly identical reading.


But on 6m it takes 7.2w drive and I only see 72w output at 
13.15v.  Advancing drive higher engages the auto-ATT, so it would 
suggest drive is high enough.


A little disappointed that 6m did not develop output per spec (80w) 
though I guess no one would note the difference of 72 vs 80.  I am 
running a 50A Astron PS which indicates 13.71v at the PS terminal  I 
have not measured what that is under load of the KXPA-100 as PS 
terminals are difficult to reach.  Voltage measured with Fluke model 17B+.


I may try adjusting the Astron to 14.2v to see if that will improve 
output; assuming similar 0.6v drop under load would result in 13.6v.


I substituted a No.10 PP power cord for the No.12 cord provided with 
the amp with no discernable difference.


73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
dubus...@gmail.com

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Re: [Elecraft] K3 and KX3 questions for Wayne

[Ray Sills]

And following up with Jim’s posting about the KXPA100 specs:  At the far end of 
a QSO, the difference between an 80 watt signal vs a 100 watt signal would be 
difficult to measure, let alone perceive by ear.  In most cases, a 6 dB 
difference in level is clearly noticeable, and that would be 25 watts vs 100 
watts.   A 3 dB difference can be heard by most people, but a 1 or 2 dB 
difference is almost impossible to notice by ear.

So, even if you are operating with just 12 V, at the input to the amp… don’t 
sweat it.  If you can’t make the QSO with 80 watts, you aren’t going to make it 
with 100 watts… not on HF, with SSB or CW.

73 de Ray
K2ULR
KX3 #211


> On May 22, 2016, at 5:46 PM, Jim Brown  wrote:
> 
> On Sun,5/22/2016 11:46 AM, N6MQL wrote:
>> Although I appreciate all of your answers I specifically asked these 
>> questions of Wayne because I was making a point to let him know of my 
>> disapproval of the fact that the KXPA100 amp is incapable of running a full 
>> 100 watts on a standard 12v battery.
> 

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Re: [Elecraft] K3 and KX3 questions for Wayne

[Bill Frantz]

An addition to Jim's comments below.

All 100W rigs, regardless of manufacturer, whether the amp is 
part of the radio or a separate unit, develop significant 
distortion as the voltage drops. We noticed the effect at CQP 
last year. We were operating on batteries as our hosts have a no 
generator rule. As our batteries got lower, our 3 stations -- 2 
K3s and a KX3 with KXPA100 -- started interfering with each 
other. The problem went away when we replaced the batteries with 
fresh ones.


This distortion will also affect your signal as received by 
distant stations, so it is undesirable in a rig unless you want 
a reputation for a bad signal.


One way to be able to get maximum runtime from your batteries is 
to use a voltage booster regulator. I use a N8XJK Boost 
Regulator from TGE. This device boosts the battery voltage to 
the radio. Mine shows 13.9 volts, receive and 13.4 volts key 
down at 100W on 160M, even with relatively low batteries. (It 
does have a low voltage cut off to protect the batteries.)


The N8XJK Boost Regulator does generate some minor birdies on 
receive, so I have it set up to only boost voltage when it 
senses RF output from the transmitter.


73 Bill AE6JV

On 5/22/16 at 2:46 PM, j...@audiosystemsgroup.com (Jim Brown) wrote:


On Sun,5/22/2016 11:46 AM, N6MQL wrote:
Although I appreciate all of your answers I specifically asked 
these questions of Wayne because I was making a point to let 
him know of my disapproval of the fact that the KXPA100 amp is 
incapable of running a full 100 watts on a standard 12v battery.


Michael,

A careful reading of the online data sheet for the KXPA100 is instructive here.

http://www.elecraft.com/KXPA100/kxpa100.htm

The first line says "100 watts at 13.8 V, 1.8 to 29.7 MHz and 
80 watts 50-54 MHz PEP CW/SSB/DATA; ± 1 dB"


Two points: First, the amplifier is rated for 13.8V, NOT 12V. 
Second, the rating is +/1 dB, which is +/- 20% power. Thus, 80W 
on the HF bands is within spec for 13.8V at the amplifier terminals.


The second line says "13.8 VDC powered; 20 A typical current 
drain (11 V with lower output. 15 V max)"


This clearly means that the unit is designed and rated for 
13.8VDC, can be operated from 11V to 15VDC, and will have 
reduced output at lower supply voltages.


Obviously, Ohm's Law dictates that resistance of the DC supply 
conductors will reduce power supply voltage at the amplifier 
terminals, so while we may have 12V or 13.8V at our battery 
terminals, the voltage at the end of 6-12 ft of cable will be a 
bit lower with a 20A load. For example, the drop in 6 ft of #10 
is 0.24v; for #12, it's 0.38V, and for #14, it's 0.6V.


As others have noted, the operating voltage in so-called 12V DC 
power systems using lead-acid batteries is not 12V, but rather 
13.8V. If you buy an AC power supply for ham gear, it will 
likely leave the factory with its voltage regulator set for 
13.8V. Open the manual or the spec sheet for nearly all ham 
gear and you will find the supply voltage specified as 13.8VDC.


-
Bill Frantz| Airline peanut bag: "Produced  | Periwinkle
(408)356-8506  | in a facility that processes   | 16345 
Englewood Ave
www.pwpconsult.com | peanuts and other nuts." - Duh | Los Gatos, 
CA 95032


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Re: [Elecraft] K3 and KX3 questions for Wayne

[Milverton M. Swire via Elecraft]

>>> I don't mind having a KXPA100 delivering 100W under 12V power supply. <<<
Simple fix!    Apply ohms Law. 

(((73))) Milverton / W9MM. 


  From: Johnny Siu via Elecraft <elecraft@mailman.qth.net>
 To: Kevin Stover <kevin.sto...@mediacombb.net>; "elecraft@mailman.qth.net" 
<elecraft@mailman.qth.net> 
 Sent: Sunday, May 22, 2016 7:46 PM
 Subject: [Elecraft] K3 and KX3 questions for Wayne
   
Hello Gentleman,
I met both Wayne and Eric in the past, they are thick skin and like questions 
right in front of their faces.  Some questions for them to address will give 
them more desire to do better.  In return, we are benefited.
Actually, I don't mind having a KXPA100 delivering 100W under 12V power supply. 
 Just leave Wayne free hands to Wayne to answer and I trust he is in a better 
position to do so.
73
Johnny VR2XMC

      寄件人︰ Kevin Stover <kevin.sto...@mediacombb.net>
 收件人︰ elecraft@mailman.qth.net 
 傳送日期︰ 2016年05月23日 (週一) 8:20 AM
 主題︰ Re: [Elecraft] K3 and KX3 questions for Wayne
  
Further down in the same online spec page it states "Compact unit ideal 
for both desktop and mobile use". Note *mobile* use where the electrical 
system supplies more than 13.8V with the engine running.
I find no mention of the KXPA100 being developed as a "portable" amp. I 
have done searches of all Elecraft docs concerning the KXPA100 and find 
NO mention of the word *portable* anywhere. Nor do I find any mention of 
some nefarious board swap early in the products life.

Maybe the OP assumed because it has a carry strap that it is a portable 
amp. Well...My TS520 has a carry strap and a DC-DC converter. No way 
that can be classified as portable, it weighs 37lbs.

To be fair I have run it at field day but we had a 10KW diesel powered 
generator on a trailer. Power was NOT and issue.

On 5/22/2016 4:46 PM, Jim Brown wrote:
> Michael,
>
> A careful reading of the online data sheet for the KXPA100 is 
> instructive here.
>
> http://www.elecraft.com/KXPA100/kxpa100.htm
>
> The first line says "100 watts at 13.8 V, 1.8 to 29.7 MHz and 80 watts 
> 50-54 MHz PEP CW/SSB/DATA; ± 1 dB"
>
> Two points: First, the amplifier is rated for 13.8V, NOT 12V. Second, 
> the rating is +/1 dB, which is +/- 20% power. Thus, 80W on the HF 
> bands is within spec for 13.8V at the amplifier terminals.
>
> The second line says "13.8 VDC powered; 20 A typical current drain (11 
> V with lower output. 15 V max)"
>
> This clearly means that the unit is designed and rated for 13.8VDC, 
> can be operated from 11V to 15VDC, and will have reduced output at 
> lower supply voltages.
>
> Obviously, Ohm's Law dictates that resistance of the DC supply 
> conductors will reduce power supply voltage at the amplifier 
> terminals, so while we may have 12V or 13.8V at our battery terminals, 
> the voltage at the end of 6-12 ft of cable will be a bit lower with a 
> 20A load. For example, the drop in 6 ft of #10 is 0.24v; for #12, it's 
> 0.38V, and for #14, it's 0.6V.
>
> As others have noted, the operating voltage in so-called 12V DC power 
> systems using lead-acid batteries is not 12V, but rather 13.8V. If you 
> buy an AC power supply for ham gear, it will likely leave the factory 
> with its voltage regulator set for 13.8V. Open the manual or the spec 
> sheet for nearly all ham gear and you will find the supply voltage 
> specified as 13.8VDC.
>
> 73, Jim K9YC

  
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Re: [Elecraft] K3 and KX3 questions for Wayne

[David Orman]

While I appreciate the motivation behind your request, you should have
asked Wayne directly, and not via an email list sent to hundreds
(thousands?) of users. If you did not want community replies, you should
not have sent an email to a community mailing list.

On Sun, May 22, 2016 at 1:46 PM, N6MQL  wrote:

> Although I appreciate all of your answers I specifically asked these
> questions of Wayne because I was making a point to let him know of my
> disapproval of the fact that the KXPA100 amp is incapable of running a full
> 100 watts on a standard 12v battery. Furthermore I was trying to get an
> explanation from the head designer as to why my amp that has a 30amp power
> supply at 15v (read on the KX3) or 15.4v at the input is unable to transmit
> at a full 100 watts on all bands.  Yes, I have the supplied cable with
> fuses attached, it's only 3 feet long, and the transmit vs' receive voltage
> is less than a volt difference.  So all of those bases have been covered.
> As noted I have also completed the KX3 power configuration, and the KX3 to
> KPA matching alignment procedure...
> I was alluded to the idea that there were a second revision of boards that
> came out for the KXPA100 after the early models were shipped.  I have also
> heard that those boards help increase the output power. Therefore I was
> asking WAYNE if this were the case, and perhaps having them would help this
> situation. As for the 12v not running the amp, this IS an issue because at
> field day we have 150 Ah batteries that run 12 volts, and it would be nice
> to have my 100 watt amp run a full 100 watts. Again, this was designed as a
> portable amp. I would expect that at 12v we should be able to get the full
> rating out of it.
>
> On another note, what may have also gotten lost due to all those trying to
> be helpful, but cluttering my original post.  I have a K3 that no longer
> puts out 100 watts on 17 meters but does on all other bands.  I was told
> this was a software issue by Tech Support.  I would like confirmation FROM
> WAYNE that this is the case, and when he may have time to address it. If
> not, I would like to know why I was told this.
>
> So again, as much as I appreciate all of you trying to help with these
> questions, I would much prefer that Wayne address them personally.  Thank
> you,
>
> --
> Michael
>
> N6MQL
>
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[Elecraft] K3 and KX3 questions for Wayne

[Johnny Siu via Elecraft]

Hello Gentleman,
I met both Wayne and Eric in the past, they are thick skin and like questions 
right in front of their faces.  Some questions for them to address will give 
them more desire to do better.  In return, we are benefited.
Actually, I don't mind having a KXPA100 delivering 100W under 12V power supply. 
 Just leave Wayne free hands to Wayne to answer and I trust he is in a better 
position to do so.
73
Johnny VR2XMC

  寄件人︰ Kevin Stover <kevin.sto...@mediacombb.net>
 收件人︰ elecraft@mailman.qth.net 
 傳送日期︰ 2016年05月23日 (週一) 8:20 AM
 主題︰ Re: [Elecraft] K3 and KX3 questions for Wayne
   
Further down in the same online spec page it states "Compact unit ideal 
for both desktop and mobile use". Note *mobile* use where the electrical 
system supplies more than 13.8V with the engine running.
I find no mention of the KXPA100 being developed as a "portable" amp. I 
have done searches of all Elecraft docs concerning the KXPA100 and find 
NO mention of the word *portable* anywhere. Nor do I find any mention of 
some nefarious board swap early in the products life.

Maybe the OP assumed because it has a carry strap that it is a portable 
amp. Well...My TS520 has a carry strap and a DC-DC converter. No way 
that can be classified as portable, it weighs 37lbs.

To be fair I have run it at field day but we had a 10KW diesel powered 
generator on a trailer. Power was NOT and issue.

On 5/22/2016 4:46 PM, Jim Brown wrote:
> Michael,
>
> A careful reading of the online data sheet for the KXPA100 is 
> instructive here.
>
> http://www.elecraft.com/KXPA100/kxpa100.htm
>
> The first line says "100 watts at 13.8 V, 1.8 to 29.7 MHz and 80 watts 
> 50-54 MHz PEP CW/SSB/DATA; ± 1 dB"
>
> Two points: First, the amplifier is rated for 13.8V, NOT 12V. Second, 
> the rating is +/1 dB, which is +/- 20% power. Thus, 80W on the HF 
> bands is within spec for 13.8V at the amplifier terminals.
>
> The second line says "13.8 VDC powered; 20 A typical current drain (11 
> V with lower output. 15 V max)"
>
> This clearly means that the unit is designed and rated for 13.8VDC, 
> can be operated from 11V to 15VDC, and will have reduced output at 
> lower supply voltages.
>
> Obviously, Ohm's Law dictates that resistance of the DC supply 
> conductors will reduce power supply voltage at the amplifier 
> terminals, so while we may have 12V or 13.8V at our battery terminals, 
> the voltage at the end of 6-12 ft of cable will be a bit lower with a 
> 20A load. For example, the drop in 6 ft of #10 is 0.24v; for #12, it's 
> 0.38V, and for #14, it's 0.6V.
>
> As others have noted, the operating voltage in so-called 12V DC power 
> systems using lead-acid batteries is not 12V, but rather 13.8V. If you 
> buy an AC power supply for ham gear, it will likely leave the factory 
> with its voltage regulator set for 13.8V. Open the manual or the spec 
> sheet for nearly all ham gear and you will find the supply voltage 
> specified as 13.8VDC.
>
> 73, Jim K9YC

  
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Kevin Stover]

Further down in the same online spec page it states "Compact unit ideal 
for both desktop and mobile use". Note *mobile* use where the electrical 
system supplies more than 13.8V with the engine running.
I find no mention of the KXPA100 being developed as a "portable" amp. I 
have done searches of all Elecraft docs concerning the KXPA100 and find 
NO mention of the word *portable* anywhere. Nor do I find any mention of 
some nefarious board swap early in the products life.


Maybe the OP assumed because it has a carry strap that it is a portable 
amp. Well...My TS520 has a carry strap and a DC-DC converter. No way 
that can be classified as portable, it weighs 37lbs.


To be fair I have run it at field day but we had a 10KW diesel powered 
generator on a trailer. Power was NOT and issue.


On 5/22/2016 4:46 PM, Jim Brown wrote:

Michael,

A careful reading of the online data sheet for the KXPA100 is 
instructive here.


http://www.elecraft.com/KXPA100/kxpa100.htm

The first line says "100 watts at 13.8 V, 1.8 to 29.7 MHz and 80 watts 
50-54 MHz PEP CW/SSB/DATA; ± 1 dB"


Two points: First, the amplifier is rated for 13.8V, NOT 12V. Second, 
the rating is +/1 dB, which is +/- 20% power. Thus, 80W on the HF 
bands is within spec for 13.8V at the amplifier terminals.


The second line says "13.8 VDC powered; 20 A typical current drain (11 
V with lower output. 15 V max)"


This clearly means that the unit is designed and rated for 13.8VDC, 
can be operated from 11V to 15VDC, and will have reduced output at 
lower supply voltages.


Obviously, Ohm's Law dictates that resistance of the DC supply 
conductors will reduce power supply voltage at the amplifier 
terminals, so while we may have 12V or 13.8V at our battery terminals, 
the voltage at the end of 6-12 ft of cable will be a bit lower with a 
20A load. For example, the drop in 6 ft of #10 is 0.24v; for #12, it's 
0.38V, and for #14, it's 0.6V.


As others have noted, the operating voltage in so-called 12V DC power 
systems using lead-acid batteries is not 12V, but rather 13.8V. If you 
buy an AC power supply for ham gear, it will likely leave the factory 
with its voltage regulator set for 13.8V. Open the manual or the spec 
sheet for nearly all ham gear and you will find the supply voltage 
specified as 13.8VDC.


73, Jim K9YC
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R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441



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Re: [Elecraft] K3 and KX3 questions for Wayne

[Mike Rhodes]

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Re: [Elecraft] K3 and KX3 questions for Wayne

[Jim Brown]

On Sun,5/22/2016 11:46 AM, N6MQL wrote:
Although I appreciate all of your answers I specifically asked these 
questions of Wayne because I was making a point to let him know of my 
disapproval of the fact that the KXPA100 amp is incapable of running a 
full 100 watts on a standard 12v battery.


Michael,

A careful reading of the online data sheet for the KXPA100 is 
instructive here.


http://www.elecraft.com/KXPA100/kxpa100.htm

The first line says "100 watts at 13.8 V, 1.8 to 29.7 MHz and 80 watts 
50-54 MHz PEP CW/SSB/DATA; ± 1 dB"


Two points: First, the amplifier is rated for 13.8V, NOT 12V. Second, 
the rating is +/1 dB, which is +/- 20% power. Thus, 80W on the HF bands 
is within spec for 13.8V at the amplifier terminals.


The second line says "13.8 VDC powered; 20 A typical current drain (11 V 
with lower output. 15 V max)"


This clearly means that the unit is designed and rated for 13.8VDC, can 
be operated from 11V to 15VDC, and will have reduced output at lower 
supply voltages.


Obviously, Ohm's Law dictates that resistance of the DC supply 
conductors will reduce power supply voltage at the amplifier terminals, 
so while we may have 12V or 13.8V at our battery terminals, the voltage 
at the end of 6-12 ft of cable will be a bit lower with a 20A load. For 
example, the drop in 6 ft of #10 is 0.24v; for #12, it's 0.38V, and for 
#14, it's 0.6V.


As others have noted, the operating voltage in so-called 12V DC power 
systems using lead-acid batteries is not 12V, but rather 13.8V. If you 
buy an AC power supply for ham gear, it will likely leave the factory 
with its voltage regulator set for 13.8V. Open the manual or the spec 
sheet for nearly all ham gear and you will find the supply voltage 
specified as 13.8VDC.


73, Jim K9YC
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Kevin Stover]

You do know what's going on this weekend right?
I'm sure once he is back from Dayton he will give your questions all of 
they attention they deserve.

What sort of watt meter are we measuring the output with?

On 5/22/2016 1:46 PM, N6MQL wrote:
Although I appreciate all of your answers I specifically asked these 
questions of Wayne because I was making a point to let him know of my 
disapproval of the fact that the KXPA100 amp is incapable of running a 
full 100 watts on a standard 12v battery. Furthermore I was trying to 
get an explanation from the head designer as to why my amp that has a 
30amp power supply at 15v (read on the KX3) or 15.4v at the input is 
unable to transmit at a full 100 watts on all bands.  Yes, I have the 
supplied cable with fuses attached, it's only 3 feet long, and the 
transmit vs' receive voltage is less than a volt difference.  So all 
of those bases have been covered. As noted I have also completed the 
KX3 power configuration, and the KX3 to KPA matching alignment 
procedure...
I was alluded to the idea that there were a second revision of boards 
that came out for the KXPA100 after the early models were shipped.  I 
have also heard that those boards help increase the output power. 
Therefore I was asking WAYNE if this were the case, and perhaps having 
them would help this situation. As for the 12v not running the amp, 
this IS an issue because at field day we have 150 Ah batteries that 
run 12 volts, and it would be nice to have my 100 watt amp run a full 
100 watts. Again, this was designed as a portable amp. I would expect 
that at 12v we should be able to get the full rating out of it.


On another note, what may have also gotten lost due to all those 
trying to be helpful, but cluttering my original post.  I have a K3 
that no longer puts out 100 watts on 17 meters but does on all other 
bands.  I was told this was a software issue by Tech Support.  I would 
like confirmation FROM WAYNE that this is the case, and when he may 
have time to address it. If not, I would like to know why I was told 
this.


So again, as much as I appreciate all of you trying to help with these 
questions, I would much prefer that Wayne address them personally.  
Thank you,





--
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441



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Re: [Elecraft] K3 and KX3 questions for Wayne

[Ron D'Eau Claire]

Actually it is a good measurement when the KXPA100 and KX3 are set up
'normally' with power to the KX3 supplied via the KXPA100.

What the KX3 will display is the voltage present at the input to the KXPA100
(because that's where the KX3 is getting its power) less any voltage drop in
the cable from the KXPA100 to the KX3.

So if the voltage reads good at the KX3 with that setup, it's good at the
KXPA100. 

73, Ron AC7AC 

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ken G
Kopp
Sent: Sunday, May 22, 2016 10:53 AM
To: Nr4c; elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 and KX3 questions for Wayne

Bill,

The front panel voltage display on a KX3 will -not- be accurate for the
voltage at the input- power connector of the KXPA100.
This voltage must be measured AT THE CONNECTOR on the rear of the KXPA100 to
know what's being delivered to the PA.

73!

K0PP

On Sun, May 22, 2016 at 9:40 AM, Nr4c <n...@widomaker.com> wrote:

> Or just use the Voltage reading displayed on the K3/KX3 front panel. 
> It's quite accurate.
>
> Sent from my iPhone
> ...nr4c. bill
>
>
> > On May 22, 2016, at 10:52 AM, David Orman <orma...@corenode.com> wrote:
> >
> > Another question - how long/what gauge is the wire running to your
> KXPA100?
> > I wouldn't expect enough drop to pull your voltage down to a point 
> > at
> which
> > it cuts back power, but you never know. Check your KX3 for the 
> > source voltage when transmitting, that'll tell you if you're 
> > dropping below the threshold for power reduction. For example, 16 
> > gauge copper will drop
> about
> > 1.2 volts on a 10 foot run @ 15A current draw.
> >
> >> On Sat, May 21, 2016 at 9:58 PM, N6MQL <n6...@arrl.net> wrote:
> >>
> >> Wayne,
> >>
> >> 2 things... First I mentioned to David S in the service department 
> >> that the K3 is no longer transmitting more than 94 watts out on 17 
> >> meters regardless of the SWR/ impedance. David said that this was a 
> >> known issue due to software and that it was being worked on. 
> >> However I haven't seen anything about this issue so I'm wondering 
> >> if this is true and if so has there been any updates to fix it.
> >> Secondly, I'm noticing that my KXPA100 can not produce more that 80
> watts
> >> on most bands and 60 on others when I don't supply it with as much 
> >> as
> 15v
> >> DC on a 30 amp supply. This after I did the KX3 / KPXA calibration 
> >> procedure. Why is it that a "mobile" amp that would normally be 
> >> powered with 12v DC from a car battery not be able to provide the 
> >> power output
> that
> >> it is sold as (100 watts)?. Has there been some kind of revisions 
> >> to the first run boards that I should be exchanging them with?
> >>
> >> Thank you for your answers  73
> >>
> >> Mike
> >> N6MQL
> >> __
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> >> orma...@corenode.com
> >>
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>
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Re: [Elecraft] K3 and KX3 questions for Wayne

[N6MQL]

Although I appreciate all of your answers I specifically asked these 
questions of Wayne because I was making a point to let him know of my 
disapproval of the fact that the KXPA100 amp is incapable of running a 
full 100 watts on a standard 12v battery. Furthermore I was trying to 
get an explanation from the head designer as to why my amp that has a 
30amp power supply at 15v (read on the KX3) or 15.4v at the input is 
unable to transmit at a full 100 watts on all bands.  Yes, I have the 
supplied cable with fuses attached, it's only 3 feet long, and the 
transmit vs' receive voltage is less than a volt difference.  So all of 
those bases have been covered. As noted I have also completed the KX3 
power configuration, and the KX3 to KPA matching alignment procedure...
I was alluded to the idea that there were a second revision of boards 
that came out for the KXPA100 after the early models were shipped.  I 
have also heard that those boards help increase the output power. 
Therefore I was asking WAYNE if this were the case, and perhaps having 
them would help this situation. As for the 12v not running the amp, this 
IS an issue because at field day we have 150 Ah batteries that run 12 
volts, and it would be nice to have my 100 watt amp run a full 100 
watts. Again, this was designed as a portable amp. I would expect that 
at 12v we should be able to get the full rating out of it.


On another note, what may have also gotten lost due to all those trying 
to be helpful, but cluttering my original post.  I have a K3 that no 
longer puts out 100 watts on 17 meters but does on all other bands.  I 
was told this was a software issue by Tech Support.  I would like 
confirmation FROM WAYNE that this is the case, and when he may have time 
to address it. If not, I would like to know why I was told this.


So again, as much as I appreciate all of you trying to help with these 
questions, I would much prefer that Wayne address them personally.  
Thank you,


--
Michael
N6MQL

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Re: [Elecraft] K3 and KX3 questions for Wayne

[Walter Underwood]

According to the manual, you can use the KXPA Utility to read the voltmeter 
inside the KXPA100.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On May 22, 2016, at 10:52 AM, Ken G Kopp  wrote:
> 
> Bill,
> 
> The front panel voltage display on a KX3 will -not- be accurate
> for the voltage at the input- power connector of the KXPA100.
> This voltage must be measured AT THE CONNECTOR on the
> rear of the KXPA100 to know what's being delivered to the PA.
> 
> 73!
> 
> K0PP
> 
> On Sun, May 22, 2016 at 9:40 AM, Nr4c  wrote:
> 
>> Or just use the Voltage reading displayed on the K3/KX3 front panel. It's
>> quite accurate.
>> 
>> Sent from my iPhone
>> ...nr4c. bill
>> 
>> 
>>> On May 22, 2016, at 10:52 AM, David Orman  wrote:
>>> 
>>> Another question - how long/what gauge is the wire running to your
>> KXPA100?
>>> I wouldn't expect enough drop to pull your voltage down to a point at
>> which
>>> it cuts back power, but you never know. Check your KX3 for the source
>>> voltage when transmitting, that'll tell you if you're dropping below the
>>> threshold for power reduction. For example, 16 gauge copper will drop
>> about
>>> 1.2 volts on a 10 foot run @ 15A current draw.
>>> 
 On Sat, May 21, 2016 at 9:58 PM, N6MQL  wrote:
 
 Wayne,
 
 2 things... First I mentioned to David S in the service department that
 the K3 is no longer transmitting more than 94 watts out on 17 meters
 regardless of the SWR/ impedance. David said that this was a known issue
 due to software and that it was being worked on. However I haven't seen
 anything about this issue so I'm wondering if this is true and if so has
 there been any updates to fix it.
 Secondly, I'm noticing that my KXPA100 can not produce more that 80
>> watts
 on most bands and 60 on others when I don't supply it with as much as
>> 15v
 DC on a 30 amp supply. This after I did the KX3 / KPXA calibration
 procedure. Why is it that a "mobile" amp that would normally be powered
 with 12v DC from a car battery not be able to provide the power output
>> that
 it is sold as (100 watts)?. Has there been some kind of revisions to the
 first run boards that I should be exchanging them with?
 
 Thank you for your answers  73
 
 Mike
 N6MQL
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>>> __
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>> 
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Ken G Kopp]

Bill,

The front panel voltage display on a KX3 will -not- be accurate
for the voltage at the input- power connector of the KXPA100.
This voltage must be measured AT THE CONNECTOR on the
rear of the KXPA100 to know what's being delivered to the PA.

73!

K0PP

On Sun, May 22, 2016 at 9:40 AM, Nr4c  wrote:

> Or just use the Voltage reading displayed on the K3/KX3 front panel. It's
> quite accurate.
>
> Sent from my iPhone
> ...nr4c. bill
>
>
> > On May 22, 2016, at 10:52 AM, David Orman  wrote:
> >
> > Another question - how long/what gauge is the wire running to your
> KXPA100?
> > I wouldn't expect enough drop to pull your voltage down to a point at
> which
> > it cuts back power, but you never know. Check your KX3 for the source
> > voltage when transmitting, that'll tell you if you're dropping below the
> > threshold for power reduction. For example, 16 gauge copper will drop
> about
> > 1.2 volts on a 10 foot run @ 15A current draw.
> >
> >> On Sat, May 21, 2016 at 9:58 PM, N6MQL  wrote:
> >>
> >> Wayne,
> >>
> >> 2 things... First I mentioned to David S in the service department that
> >> the K3 is no longer transmitting more than 94 watts out on 17 meters
> >> regardless of the SWR/ impedance. David said that this was a known issue
> >> due to software and that it was being worked on. However I haven't seen
> >> anything about this issue so I'm wondering if this is true and if so has
> >> there been any updates to fix it.
> >> Secondly, I'm noticing that my KXPA100 can not produce more that 80
> watts
> >> on most bands and 60 on others when I don't supply it with as much as
> 15v
> >> DC on a 30 amp supply. This after I did the KX3 / KPXA calibration
> >> procedure. Why is it that a "mobile" amp that would normally be powered
> >> with 12v DC from a car battery not be able to provide the power output
> that
> >> it is sold as (100 watts)?. Has there been some kind of revisions to the
> >> first run boards that I should be exchanging them with?
> >>
> >> Thank you for your answers  73
> >>
> >> Mike
> >> N6MQL
> >> __
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> >> Message delivered to orma...@corenode.com
> >>
> > __
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>
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Art Nienhouse]

*/My experience with my KXPA-100 that the power output would not ever 
get to the advertised 100 watts on 40 meters using the supplied power 
cable that came with my kit was worse.


Even after setting the 45 amp power supply to the highest out put it 
would do, the radio reported 13.8 volts on receive, on key down it would 
drop well below ( on some bands ) to 12 volts.


After replacing the pwr cable with a 10 gauge wire the supply reported 
at the radio is 14.5 rx, tx is 13.8 the power output is at 100 watts 
most bands 110 on one band and the only band I really care about is 40 
where it always has been below the other bands is now at 99 to 100 watts.


I believe that there was a firmware update that made this issue worse as 
it was at one time doing around 80 to 85 watts on 40 meters which I was 
living with, most other bands 100 to 110 watts,  using the supplied 
power cable that came with my kit.


If its sold as a mobile amp then it should be capable of doing the 
advertised 100 watts at 12 volts ..( I know the advertizing 
stated at 13.8 volts ) ..to achieve the 100 watts.


To be completely truthful it should be stated what can be expected for 
power out at 12 v connected to a car deep cycle battery with the 
supplied power cable...mine did 60 watts on 40 meters with the latest 
bata firmware.


At the very least a ( quality 10 gauge power cable ) should be supplied 
with the amp, and all 100 watt output radios.
I took the advice of this group to purchase Powerwerx Red/Black power 
cable  not the cheapest however quality is very good.

With my power supply set to 14.4 volts I get the advertized 100 watts now.

Regards
Art
ka9zap
/*
On 5/21/2016 9:58 PM, N6MQL wrote:

Wayne,

2 things... First I mentioned to David S in the service department that the K3 
is no longer transmitting more than 94 watts out on 17 meters regardless of the 
SWR/ impedance. David said that this was a known issue due to software and that 
it was being worked on. However I haven't seen anything about this issue so I'm 
wondering if this is true and if so has there been any updates to fix it.
Secondly, I'm noticing that my KXPA100 can not produce more that 80 watts on most bands 
and 60 on others when I don't supply it with as much as 15v DC on a 30 amp supply. This 
after I did the KX3 / KPXA calibration procedure. Why is it that a "mobile" amp 
that would normally be powered with 12v DC from a car battery not be able to provide the 
power output that it is sold as (100 watts)?. Has there been some kind of revisions to 
the first run boards that I should be exchanging them with?

Thank you for your answers  73

Mike
N6MQL
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Bob N3MNT]

I noticed that my KXPA100 output was a little low so I checked the output of
my 30A supply.  It was a little low.  I adjusted it up from 13.6V to 14.0
and all is well.



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Re: [Elecraft] K3 and KX3 questions for Wayne

[Nr4c]

Or just use the Voltage reading displayed on the K3/KX3 front panel. It's quite 
accurate. 

Sent from my iPhone
...nr4c. bill


> On May 22, 2016, at 10:52 AM, David Orman  wrote:
> 
> Another question - how long/what gauge is the wire running to your KXPA100?
> I wouldn't expect enough drop to pull your voltage down to a point at which
> it cuts back power, but you never know. Check your KX3 for the source
> voltage when transmitting, that'll tell you if you're dropping below the
> threshold for power reduction. For example, 16 gauge copper will drop about
> 1.2 volts on a 10 foot run @ 15A current draw.
> 
>> On Sat, May 21, 2016 at 9:58 PM, N6MQL  wrote:
>> 
>> Wayne,
>> 
>> 2 things... First I mentioned to David S in the service department that
>> the K3 is no longer transmitting more than 94 watts out on 17 meters
>> regardless of the SWR/ impedance. David said that this was a known issue
>> due to software and that it was being worked on. However I haven't seen
>> anything about this issue so I'm wondering if this is true and if so has
>> there been any updates to fix it.
>> Secondly, I'm noticing that my KXPA100 can not produce more that 80 watts
>> on most bands and 60 on others when I don't supply it with as much as 15v
>> DC on a 30 amp supply. This after I did the KX3 / KPXA calibration
>> procedure. Why is it that a "mobile" amp that would normally be powered
>> with 12v DC from a car battery not be able to provide the power output that
>> it is sold as (100 watts)?. Has there been some kind of revisions to the
>> first run boards that I should be exchanging them with?
>> 
>> Thank you for your answers  73
>> 
>> Mike
>> N6MQL
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Re: [Elecraft] K3 and KX3 questions for Wayne

[David Orman]

Another question - how long/what gauge is the wire running to your KXPA100?
I wouldn't expect enough drop to pull your voltage down to a point at which
it cuts back power, but you never know. Check your KX3 for the source
voltage when transmitting, that'll tell you if you're dropping below the
threshold for power reduction. For example, 16 gauge copper will drop about
1.2 volts on a 10 foot run @ 15A current draw.

On Sat, May 21, 2016 at 9:58 PM, N6MQL  wrote:

> Wayne,
>
> 2 things... First I mentioned to David S in the service department that
> the K3 is no longer transmitting more than 94 watts out on 17 meters
> regardless of the SWR/ impedance. David said that this was a known issue
> due to software and that it was being worked on. However I haven't seen
> anything about this issue so I'm wondering if this is true and if so has
> there been any updates to fix it.
> Secondly, I'm noticing that my KXPA100 can not produce more that 80 watts
> on most bands and 60 on others when I don't supply it with as much as 15v
> DC on a 30 amp supply. This after I did the KX3 / KPXA calibration
> procedure. Why is it that a "mobile" amp that would normally be powered
> with 12v DC from a car battery not be able to provide the power output that
> it is sold as (100 watts)?. Has there been some kind of revisions to the
> first run boards that I should be exchanging them with?
>
> Thank you for your answers  73
>
> Mike
> N6MQL
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Re: [Elecraft] K3 and KX3 questions for Wayne

[Ken G Kopp]

Mike,

A normal "12V" battery in a vehicle is almost never at 12V.  About 14.4
when the engine is running, and about 13.8 after when not under charge.  A
battery measuring "12V" is suspect.

Read the specified input voltage AT THE POWER INPUT connector ... I'll
wager it's lower than what's called for in the manual.
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[Elecraft] K3 and KX3 questions for Wayne

[N6MQL]

Wayne,

2 things... First I mentioned to David S in the service department that the K3 
is no longer transmitting more than 94 watts out on 17 meters regardless of the 
SWR/ impedance. David said that this was a known issue due to software and that 
it was being worked on. However I haven't seen anything about this issue so I'm 
wondering if this is true and if so has there been any updates to fix it. 
Secondly, I'm noticing that my KXPA100 can not produce more that 80 watts on 
most bands and 60 on others when I don't supply it with as much as 15v DC on a 
30 amp supply. This after I did the KX3 / KPXA calibration procedure. Why is it 
that a "mobile" amp that would normally be powered with 12v DC from a car 
battery not be able to provide the power output that it is sold as (100 
watts)?. Has there been some kind of revisions to the first run boards that I 
should be exchanging them with?

Thank you for your answers  73

Mike
N6MQL
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