Frank et al;
Just quoted what is in the K3S manual. No interpretation provided. I
agree that 100 watts key down is a lot for a SSB amplifier running in CW
mode. To me that says 100 watts for 10 minutes and then RX for 10
minutes. Otherwise equal TX and RX times. Who does that?
And if one is running "100 watts" then running CW or SSB for 10 minutes
might be the limit. Just speculation. On AM I might talk for 10
minutes but that is at 25% rated power output for carrier, yet it is 100
watts PEP. The 60 C is MY guideline. The KPA3A will shut down about 85
C or so.
On 6M I run my KPA500 at about 300 to 400 watts. The K3S is running
about 25 to 30 watts on 6M. At this point I'm watching the KPA500
temperature.
There is NO DX worth blowing a PA either in the K3S or the KPA500.
But I know guys that will blow things up, pushing things to the max and
beyond trying to work that DX station. I say bah humbug to that!
I just pay attention to the PA temp, specially when running digital
modes. Likewise for the KPA500.
73
Bob, K4TAX
On 4/4/2020 3:41 PM, Frank O'Donnell wrote:
Thanks for the replies.
I've enabled the PA temp display (currently showing 22C right after
power-up but before transmitting), and will keep an eye on that.
Bob, I noticed that line in the K3S manual about the CW/SSB duty
cycle. Does "100% - 10 min, 100 W key-down" mean that if you key down
without stop in CW mode it can go 10 minutes at 100 watts? That seems
like an awful lot.
Where do the recommended TPO's for 6 meters, the 50% value for JT9,
and the 60C guideline for the PA temp come from?
Thanks again,
Frank K6FOD
On 4/4/20 6:22 AM, John Simmons wrote:
Fred Cady's book:
"There are four fans speeds that turn on at different temperatures."
"If the temperature reaches 84 degrees C the KPA3 will be bypassed
until the temperature falls to stop any damage as a last-ditch backup
measure to protect your expensive power transistors from the excess
heat."
-de John NI0K
Bob McGraw K4TAX wrote on 4/3/2020 6:39 PM:
Frank:
The duty cycle for the transmitter, as stated in the manual, is; CW
and SSB modes, 100% - 10 min, 100 W key-down at 25C ambient. Do
note that 6M has reduce power values of 85 watts {51 -52 MHz} or 70
watts {52 - 54 MHz}
The duty cycle for JT-9, 1 minute transmit, 1 minute receive would
be 50%. I frequently run 100 watts on WSJT-X FT-8 with no issues.
Just pay attention to PA temperature. It should be 60 C or less.
Also this is with FANS in the automatic mode.
73
Bob, K4TAX
On 4/3/2020 4:18 PM, Frank O'Donnell wrote:
I've been using JT9 mode on 630m this winter with my K3S outputting
to an external class D amp.
Now I'm interested in trying some JT9 QSOs with some people
currently operating on 160m. For me this would mean outputting
directly from the K3S (with internal tuner) to the antenna.
Given the 1-minute cycle time for JT9, are there recommendations
(official from Elecraft, or otherwise) on maximum power to use in a
situation like this? And/or, is the answer dependent on the SWR I
can achieve with the antenna?
Thanks and 73,
Frank K6FOD
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rmcg...@blomand.net
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
