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FT8 output power KX2/KX3

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N1EU

FT8 output power KX2/KX3

What is the recommended max power output setting for the KX2 and for the
KX3 for normal FT8 use without after-market heatsink?

Thanks & 73,
Barry N1EU
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Tommy

Re: FT8 output power KX2/KX3

I use 5-10 watts without any issues. 3-4 bars on the ALC.

73!

Tom - KB2SMS

KX2 #01927

On 10/26/2017 07:50 AM, Barry N1EU wrote:
> What is the recommended max power output setting for the KX2 and for the
> KX3 for normal FT8 use without after-market heatsink?
>
> Thanks & 73,
> Barry N1EU
>
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Don Wilhelm

Re: FT8 output power KX2/KX3

In reply to this post by N1EU

Barry,

The normal recommendation is for 50% of the maximum power.
The KX3 and the KX2 will roll back power for protection if the PA
transistors get too hot.
I know the KX3 rolls back to 5 watts, but I am not sure about the level
for the KX2.

73,
Don W3FPR

On 10/26/2017 7:50 AM, Barry N1EU wrote:
> What is the recommended max power output setting for the KX2 and for the
> KX3 for normal FT8 use without after-market heatsink?
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N1EU

Re: FT8 output power KX2/KX3

Thanks Tom and Don for the responses. I'll try a few 15sec FT8 xmit cycles
at 50% (7.5W) into a dummy load while monitoring PA temp. Any guidance on
what the upper safe limit is for PA temp?

Thanks & 73,
Barry N1EU

On Thu, Oct 26, 2017 at 8:34 AM, Don Wilhelm <[hidden email]> wrote:

> Barry,
>
> The normal recommendation is for 50% of the maximum power.
> The KX3 and the KX2 will roll back power for protection if the PA
> transistors get too hot.
> I know the KX3 rolls back to 5 watts, but I am not sure about the level
> for the KX2.
>
> 73,
> Don W3FPR
>
>
> On 10/26/2017 7:50 AM, Barry N1EU wrote:
>
>> What is the recommended max power output setting for the KX2 and for the
>> KX3 for normal FT8 use without after-market heatsink?
>>
>

Don Wilhelm

Re: FT8 output power KX2/KX3

Barry,

You should be able to tolerate 60 degC measured at the PA transistor
tabs for short periods.

You can read the PA temperature in the Alternate VFO B display.

73,
Don W3FPR

On 10/26/2017 9:05 AM, Barry N1EU wrote:
> Thanks Tom and Don for the responses. I'll try a few 15sec FT8 xmit cycles
> at 50% (7.5W) into a dummy load while monitoring PA temp. Any guidance on
> what the upper safe limit is for PA temp?
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Neil Zampella

Re: FT8 output power KX2/KX3

In reply to this post by Tommy

FWIW ... with one of the KX3 aftermarket heat sinks, and after I
performed the VFO Temperature Compensation routine, I was regularly
doing 10W on the rig with JT65 with its 42 sec Tx cycle. The heatsink
did get warm enough that it worried me, and I added a salvaged 12v fan
from an old desktop computer to assist, but I never had it shut down due
to the heat. If you have one of the KX3s without a heatsink, I'd
definitely get one and install it.

Neil, KN3ILZ

On 10/26/2017 8:30 AM, Tommy wrote:

> I use 5-10 watts without any issues. 3-4 bars on the ALC.
>
> 73!
>
> Tom - KB2SMS
>
> KX2 #01927
>
>
> On 10/26/2017 07:50 AM, Barry N1EU wrote:
>> What is the recommended max power output setting for the KX2 and for the
>> KX3 for normal FT8 use without after-market heatsink?
>>
>> Thanks & 73,
>> Barry N1EU
>>
>

Elecraft mailing list

Failing K3 at 3C0L

Here is the latest from 3C0L guys, and an insight to the K3 failures,
lot of negative comments on some lists, this puts it in perspective.

Regarding K3s - those who posted negative comments on DX-Cluster about
failing K3s, please bear in mind the conditions they were being operated
at 3C0 (jumping mains voltage 120-180 V). If you dare to test transceiver,
or even better - two of them - of your beloved brand in similar conditions
for about 12 days, then lets compare the results."
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briancom

Re: Failing K3 at 3C0L

I'm going out on a limb. I've heard that some other DXpeditions had K3
failures in the RX section. RX dead TX OK. Apparently, the protection
circuitry was not enough in the close quarter multi-transmitter
operations. It would be nice to know the details or if this or is just
rumor. If this is so what in the field fixes could be done?
Alternatively, what additional steps in such contemplated operation
could be taken to further minimize such failures.

73 de Brian/K3KO

On 10/27/2017 17:02 PM, Merv Schweigert via Elecraft wrote:

> Here is the latest from 3C0L guys, and an insight to the K3 failures,
> lot of negative comments on some lists, this puts it in perspective.
>
>
>
> Regarding K3s - those who posted negative comments on DX-Cluster about
> failing K3s, please bear in mind the conditions they were being operated
> at 3C0 (jumping mains voltage 120-180 V). If you dare to test transceiver,
> or even better - two of them - of your beloved brand in similar conditions
> for about 12 days, then lets compare the results."
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
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>

w0mu

Re: Failing K3 at 3C0L

OMG a radio broke.....No other Dxpeditions have ever had equipment
failures?

On 10/27/2017 12:33 PM, Ron D'Eau Claire wrote:

> I doubt if anyone expects the receiver to survive if you hook the output of
> even a 10 watt transmitter directly to the receiver antenna connector. If
> the layout of a multi-transmitter site does not include consideration for
> substantial separation between antennas, there will be failures.
>
> The K3/K3S receivers (sub and main) are protected by carrier-operated relays
> that shunt signals to ground in the event they are strong enough to cause
> damage. Of course any protective device can be defeated (or destroyed) if
> punished too hard.
>
> Successful multi-transmitter operation begins with a rational antenna layout
> considering the power levels involved. IMX, we've always used at least one
> wavelength between transmitters running 100 watts or so (250 feet on 80, 120
> feet on 40, and so on) and we orient the antennas to minimize coupling.
>
> 73, Ron AC7AC
>
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of brian
> Sent: Friday, October 27, 2017 10:35 AM
> To: [hidden email]
> Subject: Re: [Elecraft] Failing K3 at 3C0L
>
> I'm going out on a limb. I've heard that some other DXpeditions had K3
> failures in the RX section. RX dead TX OK. Apparently, the protection
> circuitry was not enough in the close quarter multi-transmitter operations.
> It would be nice to know the details or if this or is just rumor. If this
> is so what in the field fixes could be done?
> Alternatively, what additional steps in such contemplated operation could be
> taken to further minimize such failures.
>
> 73 de Brian/K3KO
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Dave Hachadorian-2

Re: Failing K3 at 3C0L

In reply to this post by briancom

Diode D5 on the KXV3 is one weak link. A more robust replacement
is available from Digikey for $0.42
https://marc.info/?l=elecraft&m=145323127930319&w=2

Dave Hachadorian, K6LL
Yuma, AZ

-----Original Message-----
From: brian
Sent: Friday, October 27, 2017 10:35 AM
To: [hidden email]
Subject: Re: [Elecraft] Failing K3 at 3C0L

I'm going out on a limb. I've heard that some other DXpeditions
had K3
failures in the RX section. RX dead TX OK. Apparently, the
protection
circuitry was not enough in the close quarter multi-transmitter
operations. It would be nice to know the details or if this or
is just
rumor. If this is so what in the field fixes could be done?
Alternatively, what additional steps in such contemplated
operation
could be taken to further minimize such failures.

73 de Brian/K3KO

On 10/27/2017 17:02 PM, Merv Schweigert via Elecraft wrote:

> Here is the latest from 3C0L guys, and an insight to the K3
> failures,
> lot of negative comments on some lists, this puts it in
> perspective.
>
>
>
> Regarding K3s - those who posted negative comments on
> DX-Cluster about
> failing K3s, please bear in mind the conditions they were being
> operated
> at 3C0 (jumping mains voltage 120-180 V). If you dare to test
> transceiver,
> or even better - two of them - of your beloved brand in similar
> conditions
> for about 12 days, then lets compare the results."
> ______________________________________________________________
> 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]
>
> ---
> This email has been checked for viruses by AVG.
> http://www.avg.com
>

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Jim Brown-10

Re: Failing K3 at 3C0L

In reply to this post by briancom

This is far too conservative, and a far too limited approach. I can
offer several examples.

At home, I have two 3-el 20M Yagis spaced about 130 ft, and regularly
use two K3s to drive two 1,500W amps. If I aim those two Yagis so that
their driven elements are approximately colinear with each other, I can
operate CW on the same band within 60 kHz of each other and not know the
other is there! I first experienced this about four years ago with the
original K3.

Successful multi-transmitter operations require both very good radios
and very good SYSTEMS ENGINEERING. I regularly operate from W6GJB's
contesting trailer on county expeditions for CQP and 7QP. From the
trailer, we regularly run two stations, each equipped with a K3,
P3/SVGA, KPA500, KAT500, and W3NQN bandpass filter sets. We mostly work
CW, and usually have the two stations on adjacent harmonically related
bands. The 80M and 40M antennas each have double stubs inline to
suppress amplifier harmonics, and there is a serious common mode choke
on each antenna at its feedpoint. Antennas for all three bands are
within about five feet of each other on a 46 ft pneumatic mast. The K3s
have the new synth boards installed. There are photos of the trailer at
k9yc.com/7QP.pdf Since these photos were taken in May 2016, Glen
(W6GJB) has rigged the tri-bander to be at the top of the mast above the
40M dipole.

For CQP, we run at least one SSB station in addition to the two CW
stations, and we regularly operate CW and SSB on the same band. This
does, of course, require good separation of antennas, and, when
possible, colinear alignment. Operating from the same site for several
years with colinear alignment of the antennas, we found that 200 ft was
sufficient running tribanders on 20, 15, and 10, and 300-400 ft was
enough on 40 and 80 with dipoles. The SSB station(s) have the same
equipment as the CW stations.

As to failures at 3C0L -- the generator regulation failures could easily
fry power supplies, which could include frying their regulators, which
could fry the K3s. But the failures could also have been the result of
poor system engineering, or operator errors, or both. Every human being
I've ever run into screws up now and then, especially when we are tired.

As the examples cited above clearly show, there is far more to a
DXpedition or contest than hooking up a bunch of radios to a bunch of
antennas! The most successful of these operations have team members who
are good operators and are worker bees, and at least some who are good
engineers. I've seen drawings for the setups for DXpeditions that
demonstrated careful planning and great engineering. The 2008 VP6DX
expedition is a great example. It used some of the very first K3s to
come off the production line, and the systems engineering was
spectacularly good. Be sure to look at the site map and click on it to
blow it up to see the antenna layout.

http://ducie2008.dl1mgb.com/index.php

This pdf describes the receive antennas for the low bands.

http://ncjweb.com/bonus-content/200807NCJVP6DXreceiveantenna1.pdf

73, Jim K9YC

On 10/27/2017 11:33 AM, Ron D'Eau Claire wrote:
> Successful multi-transmitter operation begins with a rational antenna layout
> considering the power levels involved. IMX, we've always used at least one
> wavelength between transmitters running 100 watts or so (250 feet on 80, 120
> feet on 40, and so on) and we orient the antennas to minimize coupling.

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w0mu

Re: Failing K3 at 3C0L

In reply to this post by Dave Hachadorian-2

Honestly they should make that a simple field replaceable part.

On 10/27/2017 1:02 PM, Dave Hachadorian wrote:

> Diode D5 on the KXV3 is one weak link. A more robust replacement
> is available from Digikey for $0.42
> https://marc.info/?l=elecraft&m=145323127930319&w=2
>
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
>
> -----Original Message----- From: brian
> Sent: Friday, October 27, 2017 10:35 AM
> To: [hidden email]
> Subject: Re: [Elecraft] Failing K3 at 3C0L
>
> I'm going out on a limb. I've heard that some other DXpeditions
> had K3
> failures in the RX section. RX dead TX OK. Apparently, the
> protection
> circuitry was not enough in the close quarter multi-transmitter
> operations. It would be nice to know the details or if this or
> is just
> rumor. If this is so what in the field fixes could be done?
> Alternatively, what additional steps in such contemplated
> operation
> could be taken to further minimize such failures.
>
> 73 de Brian/K3KO
>
> On 10/27/2017 17:02 PM, Merv Schweigert via Elecraft wrote:
>> Here is the latest from 3C0L guys, and an insight to the K3
>> failures,
>> lot of negative comments on some lists, this puts it in
>> perspective.
>>
>>
>>
>> Regarding K3s - those who posted negative comments on
>> DX-Cluster about
>> failing K3s, please bear in mind the conditions they were being
>> operated
>> at 3C0 (jumping mains voltage 120-180 V). If you dare to test
>> transceiver,
>> or even better - two of them - of your beloved brand in similar
>> conditions
>> for about 12 days, then lets compare the results."
>> ______________________________________________________________
>> 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]
>>
>> ---
>> This email has been checked for viruses by AVG.
>> http://www.avg.com
>>
> ______________________________________________________________
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Edward R Cole

Re: Failing K3 at 3C0L

In reply to this post by Elecraft mailing list

I accidentally connected the wrong BNC connector to my Aux Ant jack
with directly connects to my KRX3 IF and transmitted 28-MHz 1mw
briefly into it. Suffered no damage and still works. whew!

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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K9MA

Re: Failing K3 at 3C0L

In reply to this post by w0mu

While I've seen no evidence it was the cause of the 3C0L failures, I've always wondered how long those toroids supported only by their leads could survive vibration in transport.

73,

Scott K9MA

----------

Scott Ellington

--- via iPad

>

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Matt Zilmer-3

Re: Failing K3 at 3C0L

In reply to this post by Edward R Cole

The COR probably kicked in. The sub has its own protection for high
input signal levels.

73,

matt W6NIA

On 10/27/2017 9:43 PM, Edward R Cole wrote:

> I accidentally connected the wrong BNC connector to my Aux Ant jack
> with directly connects to my KRX3 IF and transmitted 28-MHz 1mw
> briefly into it. Suffered no damage and still works. whew!
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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> Message delivered to [hidden email]

--
"A delay is better than a disaster."
-- unknown

Matt Zilmer, W6NIA
[Shiraz]

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jeff stai-2

Re: Failing K3 at 3C0L

In reply to this post by Dave Hachadorian-2

In a temp multi-op environment it's all to easy to make a mistake. During a
W1AW op I changed bands by stepping my way there and didn't go quick enough
to avoid pausing on an active band and fried my D5 extra crispy (that was a
fun repair). After that all band changes were strictly direct entry. 73
jeff wk6i

On Fri, Oct 27, 2017 at 12:02 PM, Dave Hachadorian <[hidden email]>
wrote:

> Diode D5 on the KXV3 is one weak link. A more robust replacement
> is available from Digikey for $0.42
> https://marc.info/?l=elecraft&m=145323127930319&w=2
>
> --
Jeff Stai ~ [hidden email]
Twisted Oak Winery ~ http://www.twistedoak.com/
Facebook ~ http://www.facebook.com/twistedoak
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Don Wilhelm

Re: Failing K3 at 3C0L

In reply to this post by K9MA

The testimony I can give for the toroids is that I built a K2 for a long
haul truck driver. It survived for several years in his truck with no
failures.
The only reason he had for for taking it out of the truck was that he
quit driving and got other employment.

73,
Don W3FPR

On 10/28/2017 11:26 AM, K9MA wrote:
> While I've seen no evidence it was the cause of the 3C0L failures, I've always wondered how long those toroids supported only by their leads could survive vibration in transport.
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Richard Fjeld-2

Re: Failing K3 at 3C0L

In reply to this post by Dave Hachadorian-2

This may help readers understand what the energy can be like on a nearby antenna. I was having a qso using my quarter wave inverted-L on 160 meters at 100 watts, and at the same time building a tuner. I went to connect the ladder line from my 80 meter loop that was not parallel to the L, but a wire from the loop crosses the L at 90 degrees about two feet above it at one point, otherwise nothing close. I got an RF burn that had me yelling. Not good separation, but I never considered the possibility of an RF burn with the separation I did have.

Rich, n0ce

From: Dave Hachadorian<mailto:[hidden email]>
Sent: Friday, October 27, 2017 2:05 PM
To: Reflector Elecraft<mailto:[hidden email]>
Subject: Re: [Elecraft] Failing K3 at 3C0L

Diode D5 on the KXV3 is one weak link. A more robust replacement
is available from Digikey for $0.42
https://marc.info/?l=elecraft&m=145323127930319&w=2

Dave Hachadorian, K6LL
Yuma, AZ

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