K2 running QRP

[JEAN-FRANCOIS MENARD-3]

Hi,

I know I read sometime a message telling that we must use the K2 at a
maximum power level of 10W to prevent such overheating, or final to
blow...... I'm not sure if I dream it or it is a real concern.

Yesterday, I checked my K2 running at full QRP power on every band
using the dummy load and my meter, I mesured the output level since I
added the internal antenna tuner KAT.... just to make sure that
everything is working fine. I have a CAL CUR set at 3.5A as suggested
in the manual. On 40M at 7.100 Khz, I got a nearly 19V DC on my dummy
load... so about 14.6W....

Can I run my K2 at full QRP power ?

73


===========================
Jean-François Ménard / VA2VYZ
Elecraft K2 #4130

http://homepage.mac.com/jfmenard
===========================
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[Don Wilhelm-3]

Jean-Francois,

Whether you can run your K2 at full power or not depends on the duty cycle.
For data modes where the duty cycle is 100%, the answer is NO - in fact you
should keep the power down to about 5 watts for continuous duty modes.

For CW and SSB, operating at 14 watts should present no problem since the
duty cycles with these modes is 50% or less.  Continuous key-down should be
avoided except for short periods.

73,
Don W3FPR

----- Original Message -----
From: "Jean-François Ménard" <[hidden email]>
To: "Elecraft - Maling List" <[hidden email]>
Sent: Thursday, December 30, 2004 6:49 AM
Subject: [Elecraft] K2 running QRP


Hi,

I know I read sometime a message telling that we must use the K2 at a
maximum power level of 10W to prevent such overheating, or final to
blow...... I'm not sure if I dream it or it is a real concern.

Yesterday, I checked my K2 running at full QRP power on every band
using the dummy load and my meter, I mesured the output level since I
added the internal antenna tuner KAT.... just to make sure that
everything is working fine. I have a CAL CUR set at 3.5A as suggested
in the manual. On 40M at 7.100 Khz, I got a nearly 19V DC on my dummy
load... so about 14.6W....

Can I run my K2 at full QRP power ?

73


===========================
Jean-François Ménard / VA2VYZ
Elecraft K2 #4130

http://homepage.mac.com/jfmenard
===========================
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[Ron D'Eau Claire-2]

Don, W3FPR wrote:
Whether you can run your K2 at full power or not depends on the duty cycle.
For data modes where the duty cycle is 100%, the answer is NO - in fact you
should keep the power down to about 5 watts for continuous duty modes.

For CW and SSB, operating at 14 watts should present no problem since the
duty cycles with these modes is 50% or less.  Continuous key-down should be
avoided except for short periods.

---------------------------------------

One caveat to Don's comments: When running SSB, keep the output power at 10
watts PEP or less, especially on 10 and 12 meters (but I'm not why those
bands are more important than the others). Distortion products increase
rapidly running SSB when you exceed 10 watts PEP. Of course that does not
apply to CW. Then the heating issues Don mentioned are the only concerns.

The newest firmware includes a power limiting function defaults to set the
maximum power out to 10 watts on 10 and 12 meters. It's adjusted by the Po
28 command on the secondary Menu.

Ron AC7AC


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