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Re: K3 Drive Levels and the SPE 1.3K-FA

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john@kk9a.com

Re: K3 Drive Levels and the SPE 1.3K-FA

I have operated RTTY with my K3S in the 11 watt range not knowing that
this was bad for the LPAs. It would be nice if the Elecraft K3/K3S
would allow the option to turn on the 100 watt power amp and a lower
power setting.

John KK9A

dgb ns9i wrote:

I run a lot of rtty and digital with my K3. I always set the amp to the
mid range getting 8-900w out. It takes only 8-11 w drive from the K3 to
accomplish that.

Note: SPE recommends to run the amp in Mid Range for digital operation.
When I first got the amp I made the mistake of running it in the high
range and melted the copper heat sink, which was not considered a
warranty repair, and was an expensive lesson learned.

Over the course of the 3 yrs. that I've owned the amp, I have blown 4
LPA's in the K3 running it at 8-11w. With latest repair the tech
informed me that the "LPA is not rated for continuous duty at upper
power levels (like the digital Modes)" They suggested running 13w vs 11w
so the LPA wouldn't be used. If I do that it over-drives the SPE in the
mid-range.

What is my suggested recourse?

thanks 73 Dwight NS9I

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Bob McGraw - K4TAX

Re: K3 Drive Levels and the SPE 1.3K-FA

Why not add a 1 dB or 2 dB attenuator in line at the input of the amp?
That would allow for a bit higher drive power from the K3S. Three
carbon resistors will make a nice Pi attenuator.

73

Bob, K4TAX

On 11/21/2019 9:42 AM, [hidden email] wrote:

> I have operated RTTY with my K3S in the 11 watt range not knowing that
> this was bad for the LPAs. It would be nice if the Elecraft K3/K3S
> would allow the option to turn on the 100 watt power amp and a lower
> power setting.
>
> John KK9A
>
> dgb ns9i wrote:
>
> I run a lot of rtty and digital with my K3. I always set the amp to the
> mid range getting 8-900w out. It takes only 8-11 w drive from the K3 to
> accomplish that.
>
> Note: SPE recommends to run the amp in Mid Range for digital operation.
> When I first got the amp I made the mistake of running it in the high
> range and melted the copper heat sink, which was not considered a
> warranty repair, and was an expensive lesson learned.
>
> Over the course of the 3 yrs. that I've owned the amp, I have blown 4
> LPA's in the K3 running it at 8-11w. With latest repair the tech
> informed me that the "LPA is not rated for continuous duty at upper
> power levels (like the digital Modes)" They suggested running 13w vs 11w
> so the LPA wouldn't be used. If I do that it over-drives the SPE in the
> mid-range.
>
> What is my suggested recourse?
>
> thanks 73 Dwight NS9I
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Joe Subich, W4TV-4

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by john@kk9a.com

It would be more appropriate if SPE shipped their amplifiers to
the US with the proper (legal) attenuator in place. That way one
would be running the K3/K3s at 30 Watts in the first place.

73,

... Joe, W4TV

On 2019-11-21 10:42 AM, [hidden email] wrote:

> I have operated RTTY with my K3S in the 11 watt range not knowing that
> this was bad for the LPAs. It would be nice if the Elecraft K3/K3S would
> allow the option to turn on the 100 watt power amp and a lower power
> setting.
>
> John KK9A
>
> dgb ns9i wrote:
>
> I run a lot of rtty and digital with my K3. I always set the amp to the
> mid range getting 8-900w out. It takes only 8-11 w drive from the K3 to
> accomplish that.
>
> Note: SPE recommends to run the amp in Mid Range for digital operation.
> When I first got the amp I made the mistake of running it in the high
> range and melted the copper heat sink, which was not considered a
> warranty repair, and was an expensive lesson learned.
>
> Over the course of the 3 yrs. that I've owned the amp, I have blown 4
> LPA's in the K3 running it at 8-11w. With latest repair the tech
> informed me that the "LPA is not rated for continuous duty at upper
> power levels (like the digital Modes)" They suggested running 13w vs 11w
> so the LPA wouldn't be used. If I do that it over-drives the SPE in the
> mid-range.
>
> What is my suggested recourse?
>
> thanks 73 Dwight NS9I
>

NS9I WI

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by Bob McGraw - K4TAX

Yes, but, that also attenuates receive. I know, not much but I need
every fraction of a db on 80 and 160 for those weak ATNO's. Yes I know I
could switch one in/out but, remoting adds another can of worms,
especially when remoting.

I received some excellent advice from Fabio IK6ZER on the SPE reflector
and think that will alleviate any further LPA problems. We'll see, I get
the K3 back today.

Email me off-list and I will share that.

73 Dwight NS9I

On 11/21/2019 9:47 AM, Bob McGraw K4TAX wrote:

> Why not add a 1 dB or 2 dB attenuator in line at the input of the
> amp? That would allow for a bit higher drive power from the K3S.
> Three carbon resistors will make a nice Pi attenuator.
>
> 73
>
> Bob, K4TAX
>
> On 11/21/2019 9:42 AM, [hidden email] wrote:
>> I have operated RTTY with my K3S in the 11 watt range not knowing
>> that this was bad for the LPAs. It would be nice if the Elecraft
>> K3/K3S would allow the option to turn on the 100 watt power amp and a
>> lower power setting.
>>
>> John KK9A
>>
>> dgb ns9i wrote:
>>
>> I run a lot of rtty and digital with my K3. I always set the amp to the
>> mid range getting 8-900w out. It takes only 8-11 w drive from the K3 to
>> accomplish that.
>>
>> Note: SPE recommends to run the amp in Mid Range for digital operation.
>> When I first got the amp I made the mistake of running it in the high
>> range and melted the copper heat sink, which was not considered a
>> warranty repair, and was an expensive lesson learned.
>>
>> Over the course of the 3 yrs. that I've owned the amp, I have blown 4
>> LPA's in the K3 running it at 8-11w. With latest repair the tech
>> informed me that the "LPA is not rated for continuous duty at upper
>> power levels (like the digital Modes)" They suggested running 13w vs 11w
>> so the LPA wouldn't be used. If I do that it over-drives the SPE in the
>> mid-range.
>>
>> What is my suggested recourse?
>>
>> thanks 73 Dwight NS9I
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
> ______________________________________________________________
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>
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Bob McGraw - K4TAX

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by Joe Subich, W4TV-4

That is correct.   The current FCC regulation requires that an amp be
limited to 15 dB of gain.

Therefore, 900 watts out with 11 watts of drive is 19.12 dB gain.
Even with 800 watts out and 11 watts of drive the gain would be 18.61
dB. Not exactly legal in the USA.   dB = 10log(p1/p2)   Thus 30 watts
input and 900 watts output is 14.77 dB gain. A ~3 db pad on the input
would correct the issue and make the amp "legal" to use and import into
the USA.   I bet someone at SPE fudged the numbers on the paperwork.

73

Bob, K4TAX

On 11/21/2019 10:32 AM, Joe Subich, W4TV wrote:

>
>
> It would be more appropriate if SPE shipped their amplifiers to
> the US with the proper (legal) attenuator in place. That way one
> would be running the K3/K3s at 30 Watts in the first place.
>
> 73,
>
> ... Joe, W4TV
>
> On 2019-11-21 10:42 AM, [hidden email] wrote:
>> I have operated RTTY with my K3S in the 11 watt range not knowing
>> that this was bad for the LPAs. It would be nice if the Elecraft
>> K3/K3S would allow the option to turn on the 100 watt power amp and a
>> lower power setting.
>>
>> John KK9A
>>
>> dgb ns9i wrote:
>>
>> I run a lot of rtty and digital with my K3. I always set the amp to the
>> mid range getting 8-900w out. It takes only 8-11 w drive from the K3 to
>> accomplish that.
>>
>> Note: SPE recommends to run the amp in Mid Range for digital operation.
>> When I first got the amp I made the mistake of running it in the high
>> range and melted the copper heat sink, which was not considered a
>> warranty repair, and was an expensive lesson learned.
>>
>> Over the course of the 3 yrs. that I've owned the amp, I have blown 4
>> LPA's in the K3 running it at 8-11w. With latest repair the tech
>> informed me that the "LPA is not rated for continuous duty at upper
>> power levels (like the digital Modes)" They suggested running 13w vs 11w
>> so the LPA wouldn't be used. If I do that it over-drives the SPE in the
>> mid-range.
>>
>> What is my suggested recourse?
>>
>> thanks 73 Dwight NS9I
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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LDE

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by john@kk9a.com

I only work RTTY with 5 ... 8 W input from the K3S. That's enough.
73
Lutz, DL7UGO

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KeithWE6R

Re: K3 Drive Levels and the SPE 1.3K-FA

Administrator

In reply to this post by john@kk9a.com

You can play with the Config Menu watt meter calibration high and low
numbers to get the switch-over point different.
IE where the Low power amp (LPA) switches to 100 amp (KPA3). This
happens at 12W "indicated".
The two Calibration numbers are for all bands!

So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6
meters switches at 8W)!
Make a note of both numbers so you can put them back!
Extreme numbers to get the KPA3 to click in at lower actual power levels
would be to set both for 180 (max).
You will have to use an external watt-meter to see what is going on as
the K3 internal watt-meter readout is all out of calibration now!!
I just played with a radio and it switches over at about 7 watts with
both numbers at 180
Have fun!
Keith WE6R

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NS9I WI

Re: K3 Drive Levels and the SPE 1.3K-FA

Thanks for the good info Keith - I quit using 12w yrs ago as one E'craft
tech told me after the 1st one blew.

Also heard from another that I could turn the fans on all the time which
should help as normally they are only on when you go to 13w and up.

Will play with them - t u 73 Dwight NS9I

On 11/21/2019 4:04 PM, Keith Trinity WE6R wrote:

> You can play with the Config Menu watt meter calibration high and low
> numbers to get the switch-over point different.
> IE where the Low power amp (LPA) switches to 100 amp (KPA3). This
> happens at 12W "indicated".
> The two Calibration numbers are for all bands!
>
> So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6
> meters switches at 8W)!
> Make a note of both numbers so you can put them back!
> Extreme numbers to get the KPA3 to click in at lower actual power
> levels would be to set both for 180 (max).
> You will have to use an external watt-meter to see what is going on as
> the K3 internal watt-meter readout is all out of calibration now!!
> I just played with a radio and it switches over at about 7 watts with
> both numbers at 180
> Have fun!
> Keith WE6R
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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>

Dennis Ashworth-2

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by john@kk9a.com

Makes you wonder how K3/10 users fair running high duty cycle modes at full output. I’ve replaced two sets of LPF drivers running 10W WSJT on my K3/100. No more! Now I advance the power until the amplifier engages (~12W). Hopefully this reduces driver dissipation.

Dennis, K7FL

> On Nov 21, 2019, at 5:15 PM, dgb <[hidden email]> wrote:
>
> Thanks for the good info Keith - I quit using 12w yrs ago as one E'craft tech told me after the 1st one blew.
>
> Also heard from another that I could turn the fans on all the time which should help as normally they are only on when you go to 13w and up.
>
> Will play with them - t u 73 Dwight NS9I
>
>>> On 11/21/2019 4:04 PM, Keith Trinity WE6R wrote:
>> You can play with the Config Menu watt meter calibration high and low numbers to get the switch-over point different.
>> IE where the Low power amp (LPA) switches to 100 amp (KPA3). This happens at 12W "indicated".
>> The two Calibration numbers are for all bands!
>> So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6 meters switches at 8W)!
>> Make a note of both numbers so you can put them back!
>> Extreme numbers to get the KPA3 to click in at lower actual power levels would be to set both for 180 (max).
>> You will have to use an external watt-meter to see what is going on as the K3 internal watt-meter readout is all out of calibration now!!
>> I just played with a radio and it switches over at about 7 watts with both numbers at 180
>> Have fun!
>> Keith WE6R
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
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>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
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Bob McGraw - K4TAX

Re: K3 Drive Levels and the SPE 1.3K-FA

I learned my lesson running 12 to 15 watts or so having to replace the KPA3A twice. I now run 20 to 25 watts driving my KPA500 to rated output. Be it CW, SSB or digital modes. Otherwise it is 100 watts when not running the KPA500. Running conservative power doesn't get it.

Bob, K4TAX

Sent from my iPhone

> On Nov 21, 2019, at 9:15 PM, Dennis Ashworth <[hidden email]> wrote:
>
> Makes you wonder how K3/10 users fair running high duty cycle modes at full output. I’ve replaced two sets of LPF drivers running 10W WSJT on my K3/100. No more! Now I advance the power until the amplifier engages (~12W). Hopefully this reduces driver dissipation.
>
> Dennis, K7FL
>
>
>> On Nov 21, 2019, at 5:15 PM, dgb <[hidden email]> wrote:
>>
>> Thanks for the good info Keith - I quit using 12w yrs ago as one E'craft tech told me after the 1st one blew.
>>
>> Also heard from another that I could turn the fans on all the time which should help as normally they are only on when you go to 13w and up.
>>
>> Will play with them - t u 73 Dwight NS9I
>>
>>>> On 11/21/2019 4:04 PM, Keith Trinity WE6R wrote:
>>> You can play with the Config Menu watt meter calibration high and low numbers to get the switch-over point different.
>>> IE where the Low power amp (LPA) switches to 100 amp (KPA3). This happens at 12W "indicated".
>>> The two Calibration numbers are for all bands!
>>> So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6 meters switches at 8W)!
>>> Make a note of both numbers so you can put them back!
>>> Extreme numbers to get the KPA3 to click in at lower actual power levels would be to set both for 180 (max).
>>> You will have to use an external watt-meter to see what is going on as the K3 internal watt-meter readout is all out of calibration now!!
>>> I just played with a radio and it switches over at about 7 watts with both numbers at 180
>>> Have fun!
>>> Keith WE6R
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>> ______________________________________________________________
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>>
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>> Please help support this email list:
> ______________________________________________________________
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ke9uw

Re: K3 Drive Levels and the SPE 1.3K-FA

I thought the answer was to run the KPA by going up to 12 or 15 watts. What is the LPA running when when the power is at 12 or 15 watts? What is it running when the power is at 20 or 25 watts?

Chuck Jack Hawley
KE9UW

Sent from my iPhone, cjack

> On Nov 21, 2019, at 10:32 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> I learned my lesson running 12 to 15 watts or so having to replace the KPA3A twice. I now run 20 to 25 watts driving my KPA500 to rated output. Be it CW, SSB or digital modes. Otherwise it is 100 watts when not running the KPA500. Running conservative power doesn't get it.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
>> On Nov 21, 2019, at 9:15 PM, Dennis Ashworth <[hidden email]> wrote:
>>
>> Makes you wonder how K3/10 users fair running high duty cycle modes at full output. I’ve replaced two sets of LPF drivers running 10W WSJT on my K3/100. No more! Now I advance the power until the amplifier engages (~12W). Hopefully this reduces driver dissipation.
>>
>> Dennis, K7FL
>>
>>
>>> On Nov 21, 2019, at 5:15 PM, dgb <[hidden email]> wrote:
>>>
>>> Thanks for the good info Keith - I quit using 12w yrs ago as one E'craft tech told me after the 1st one blew.
>>>
>>> Also heard from another that I could turn the fans on all the time which should help as normally they are only on when you go to 13w and up.
>>>
>>> Will play with them - t u 73 Dwight NS9I
>>>
>>>>> On 11/21/2019 4:04 PM, Keith Trinity WE6R wrote:
>>>> You can play with the Config Menu watt meter calibration high and low numbers to get the switch-over point different.
>>>> IE where the Low power amp (LPA) switches to 100 amp (KPA3). This happens at 12W "indicated".
>>>> The two Calibration numbers are for all bands!
>>>> So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6 meters switches at 8W)!
>>>> Make a note of both numbers so you can put them back!
>>>> Extreme numbers to get the KPA3 to click in at lower actual power levels would be to set both for 180 (max).
>>>> You will have to use an external watt-meter to see what is going on as the K3 internal watt-meter readout is all out of calibration now!!
>>>> I just played with a radio and it switches over at about 7 watts with both numbers at 180
>>>> Have fun!
>>>> Keith WE6R
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>>
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>>> Please help support this email list:
>> ______________________________________________________________
>> Elecraft mailing list
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>>
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>
>
> ______________________________________________________________
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Chuck, KE9UW

ke9uw

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by Bob McGraw - K4TAX

Oh I just reread your post. My mistake. So running low power on the KPA is also problematic?

Chuck Jack Hawley
KE9UW

Sent from my iPhone, cjack

Chuck, KE9UW

Bob McGraw - K4TAX

Re: K3 Drive Levels and the SPE 1.3K-FA

In reply to this post by ke9uw

With the KPA3A / 100 watt amp active, which switches in at 12 watts, the
LPA then runs about 1 to 5 watts. The issue I encountered was running
the KPA3A / 100 watt amp, at the lower end of the power range being 15
or so watts. I encountered two failures of the KPA3A amp module.

I now stay away from that power level thus running 20 to 25 watts from
the KPA3A. I've been doing this since May 2018 when the last KPA3A was
replaced. I was also advised by another ham who experienced several
KPA3A failures to "stay away from 15 watts". The last KPA3A is the Rev E
model that, according to the report from Elecraft, states "Replaced
KPA3A Rev B with the more stable KPA3A Rev E amp".

The discussion can be confusing as the LPA runs normally up to about 12
to watts but can be pushed to near 15 watts. The KPA switches in the
circuit at ~12 watts. {Listen for the relay click} General discussion
surrounds running the LPA at 12 to 15 watts in high duty cycle modes,
thus causing failure of the LPA. The devices are only heat sinked to
the bottom panel and no forced air cooling is provided for the LPA.

73

Bob, K4TAX

On 11/22/2019 7:08 AM, hawley, charles j jr wrote:
> I thought the answer was to run the KPA by going up to 12 or 15 watts. What is the LPA running when when the power is at 12 or 15 watts? What is it running when the power is at 20 or 25 watts?
>
> Chuck Jack Hawley
> KE9UW
>
>
>

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Roger D Johnson

Re: K3 Drive Levels and the SPE 1.3K-FA

I purchased one of these amps about two years ago. I expected it to require
50 to 60 watts of drive for full output but it only took half that. I was
worried about screwing up and hitting it with 100 watts from the K3 and
blowing the final transistor. I knew there was a pad on the input and I
figured it would be fairly simple to increase the attenuation 2 db or so.
I pulled the covers off the amp and discovered that there were 2 pads on
the input! The first was TO-220 style resistors mounted to a chassis rail
and the second was conventional wire-wound resistors mounted on the PA
circuit board. Replacing the TO-220 resistors looked like it would involve
quite a bit of disassembly and probably would void the warranty. Tack soldering
some resistors on the second pad to increase the attenuation would be much
easier and could be easily removed if it had to go back for service. Problem
solved, right? Nope. I discovered that the amp senses drive power after the
first pad. This meant the amp kept tripping off with overdrive warnings! I
contacted the factory to see if there was an adjustment I could make and was
told it would have to come back for "realignment"!

I now have a KPA1500!

73, Roger

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Eric Norris-2

Re: K3 Drive Levels

In reply to this post by Dennis Ashworth-2

I noticed the LPA was getting quite hot when running wspr at 5w for days at
time--even with 15% tx cycle. My workaround is a six-inch computer fan set
vertical on the right side of the k3, blowing quiet air on the right side
and bottom of the k3. It seems to work. I also have used a tiny 2"
squirrel-cage fan blowing air under the XV144 during high duty-cycle modes
in WSJT. The five high-volume fans I run on the Henry 2002A, to keep from
blowing tubes, on the other hand, are a freight-train-in-a-shack (TM).

73, Eric WD6DBM

73 Eric WD6DBM

On Thu, Nov 21, 2019, 7:20 PM Dennis Ashworth <[hidden email]>
wrote:

> Makes you wonder how K3/10 users fair running high duty cycle modes at
> full output. I’ve replaced two sets of LPF drivers running 10W WSJT on my
> K3/100. No more! Now I advance the power until the amplifier engages
> (~12W). Hopefully this reduces driver dissipation.
>
> Dennis, K7FL
>
>
> > On Nov 21, 2019, at 5:15 PM, dgb <[hidden email]> wrote:
> >
> > Thanks for the good info Keith - I quit using 12w yrs ago as one
> E'craft tech told me after the 1st one blew.
> >
> > Also heard from another that I could turn the fans on all the time which
> should help as normally they are only on when you go to 13w and up.
> >
> > Will play with them - t u 73 Dwight NS9I
> >
> >>> On 11/21/2019 4:04 PM, Keith Trinity WE6R wrote:
> >> You can play with the Config Menu watt meter calibration high and low
> numbers to get the switch-over point different.
> >> IE where the Low power amp (LPA) switches to 100 amp (KPA3). This
> happens at 12W "indicated".
> >> The two Calibration numbers are for all bands!
> >> So; Go into config menu WMTR LP (below 12W) or HP (above 12W). (note 6
> meters switches at 8W)!
> >> Make a note of both numbers so you can put them back!
> >> Extreme numbers to get the KPA3 to click in at lower actual power
> levels would be to set both for 180 (max).
> >> You will have to use an external watt-meter to see what is going on as
> the K3 internal watt-meter readout is all out of calibration now!!
> >> I just played with a radio and it switches over at about 7 watts with
> both numbers at 180
> >> Have fun!
> >> Keith WE6R
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