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Power output keeps folding back to 5 watts on my KX2

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Tommy

Power output keeps folding back to 5 watts on my KX2

Hi folks,

I'm running FT8 with a KX2 powered by a power supply. The rig
keeps folding back from 10-12 watts to 5 every time and it's barely even
warm. I'll set it to 12W for instance, it'll transmit fine at that
level but when done cut back to 5w. I don't transmit often enough for it
to get hot enough to protect itself. AGC is off. Any ideas? I appreciate
any feedback.

73 de Tom - KB2SMS

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Tommy

Re: Power output keeps folding back to 5 watts on my KX2

Ahhh, O.K., with my 13.2v Astron it's showing 10.3 - 10.8. I guess
for now with this power supply I'll have to settle for 5 watts. Thank
you for the quick reply.

Tom - KB2SMS

On 3/18/19 2:36 PM, Walter Underwood wrote:

> Set the display to show the power supply voltage and watch it while you transmit. The transmitter requires a voltage over 11 V for more than 5 W.
>
> If the voltage is dropping below 11 V, that is the problem.
>
> This in the specifications section of the KX3 manual.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Mar 18, 2019, at 11:33 AM, Tommy <[hidden email]> wrote:
>>
>> Hi folks,
>>
>> I'm running FT8 with a KX2 powered by a power supply. The rig keeps folding back from 10-12 watts to 5 every time and it's barely even warm. I'll set it to 12W for instance, it'll transmit fine at that level but when done cut back to 5w. I don't transmit often enough for it to get hot enough to protect itself. AGC is off. Any ideas? I appreciate any feedback.
>>
>> 73 de Tom - KB2SMS
>>
>> ______________________________________________________________
>> Elecraft mailing list
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>>
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>
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Richard Corfield

Re: Power output keeps folding back to 5 watts on my KX2

Don't Elecraft recommend using lower power for high duty digital modes?
(Though FT8 us 15s bursts so not as high duty as some).

- Richard

On Mon, 18 Mar 2019 at 18:46, Tommy <[hidden email]> wrote:

> Ahhh, O.K., with my 13.2v Astron it's showing 10.3 - 10.8. I guess
> for now with this power supply I'll have to settle for 5 watts. Thank
> you for the quick reply.
>
> Tom - KB2SMS
>
>
> On 3/18/19 2:36 PM, Walter Underwood wrote:
> > Set the display to show the power supply voltage and watch it while you
> transmit. The transmitter requires a voltage over 11 V for more than 5 W.
> >
> > If the voltage is dropping below 11 V, that is the problem.
> >
> > This in the specifications section of the KX3 manual.
> >
> > wunder
> > K6WRU
> > Walter Underwood
> > CM87wj
> > http://observer.wunderwood.org/ (my blog)
> >
> >> On Mar 18, 2019, at 11:33 AM, Tommy <[hidden email]> wrote:
> >>
> >> Hi folks,
> >>
> >> I'm running FT8 with a KX2 powered by a power supply. The rig
> keeps folding back from 10-12 watts to 5 every time and it's barely even
> warm. I'll set it to 12W for instance, it'll transmit fine at that level
> but when done cut back to 5w. I don't transmit often enough for it to get
> hot enough to protect itself. AGC is off. Any ideas? I appreciate any
> feedback.
> >>
> >> 73 de Tom - KB2SMS
> >>
> >> ______________________________________________________________
> >> 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
> > ______________________________________________________________
> > 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
> >
> ______________________________________________________________
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Bill Frantz

Re: Power output keeps folding back to 5 watts on my KX2

Based on a presentation by Eric at the West Valley Amateur Radio
Association, Elecraft tends to build their equipment to run at
full advertised power with digital modes. Their model is a RTTY
contester calling CQ with 60% to 70% of the time transmitting.
He indicated that the KPA1500 would run for 5 minutes at full
output before needing a rest.

I have not had any problems running my K3 at 100W with FT8.
Interestingly, the fans speed up during the receive part of the cycle.

73 Bill AE6JV

On 3/18/19 at 1:39 PM, [hidden email] (Richard
Corfield) wrote:

>Don't Elecraft recommend using lower power for high duty digital modes?
>(Though FT8 us 15s bursts so not as high duty as some).

-------------------------------------------------------------------------------------
Bill Frantz | Government is not reason, it is not
eloquence, it is force; like
408-356-8506 | a fire, a troublesome servant and a fearful
master. Never for a
www.pwpconsult.com | moment should it be left to irresponsible
action. Geo Washington

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Don Wilhelm

Re: Power output keeps folding back to 5 watts on my KX2

In reply to this post by Tommy

Tommy,

That is too much voltage drop. Check all your power connections to be
sure they are tight. If the power supply terminals rotate even a little
bit, open the power supply and tighten the terminals securely.

Since the KX2 power control tries to maintain the set power, if the
voltage drops, it has to draw more current. That means your KX2 may be
exceeding the current limits due to the reduced voltage.

73,
Don W3FPR

On 3/18/2019 2:47 PM, Tommy wrote:
> Ahhh, O.K., with my 13.2v Astron it's showing 10.3 - 10.8. I guess
> for now with this power supply I'll have to settle for 5 watts. Thank
> you for the quick reply.
>
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Nr4c

Re: Power output keeps folding back to 5 watts on my KX2

In reply to this post by Bill Frantz

Walter.

While I suspect that voltage requirements for the KX3 are similar to those of the KX2, its a KX2 as the device in question.

And I agree with Don. The underlying issue here is why is the power supply voltage so low? The KX2 (or KX3) shouldn’t draw more than around three Amps under full TX power.

Sent from my iPhone
...nr4c. bill

> On Mar 18, 2019, at 5:00 PM, Walter Underwood <[hidden email]> wrote:
>
> Based on the KX3 specifications, it is designed to run at lower power for full-carrier modes.
>
> From the transmitter specifications on page 54 of the KX3 Owner’s Manual:
>
> "5 W or less recommended for high-duty-cycle modes (FM, AM, DATA). Power will automatically be reduced if PA temperature or current limits are exceeded.”
>
> I’d check the KX2 specs for info on that model.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Mar 18, 2019, at 1:55 PM, Bill Frantz <[hidden email]> wrote:
>>
>> Based on a presentation by Eric at the West Valley Amateur Radio Association, Elecraft tends to build their equipment to run at full advertised power with digital modes. Their model is a RTTY contester calling CQ with 60% to 70% of the time transmitting. He indicated that the KPA1500 would run for 5 minutes at full output before needing a rest.
>>
>> I have not had any problems running my K3 at 100W with FT8. Interestingly, the fans speed up during the receive part of the cycle.
>>
>> 73 Bill AE6JV
>>
>>> On 3/18/19 at 1:39 PM, [hidden email] (Richard Corfield) wrote:
>>>
>>> Don't Elecraft recommend using lower power for high duty digital modes?
>>> (Though FT8 us 15s bursts so not as high duty as some).
>>
>> -------------------------------------------------------------------------------------
>> Bill Frantz | Government is not reason, it is not eloquence, it is force; like
>> 408-356-8506 | a fire, a troublesome servant and a fearful master. Never for a
>> www.pwpconsult.com | moment should it be left to irresponsible action. Geo Washington
>>
>> ______________________________________________________________
>> 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
>
> ______________________________________________________________
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>
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