max power suggested on PSK with K2/100

[John Wiener]

I just worked KJ5XF who suggested that running 50W PSK would fry the  
finals.  I thought 50 was about max for safe PSK.
What's the latest on this?

Thanks

John
AB8O
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[Mike Short]

25W. There has been several discussions this week about PSK output. Since it
is a keydown mode PSK can be thought of as AM mode as far as power ratings,
and so 1/4 of your rated output should be the max.  

Mike
AI4NS

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John Wiener
Sent: Saturday, June 02, 2007 8:00 AM
To: Elecraft email email
Subject: [Elecraft] max power suggested on PSK with K2/100

I just worked KJ5XF who suggested that running 50W PSK would fry the  
finals.  I thought 50 was about max for safe PSK.
What's the latest on this?

Thanks

John
AB8O

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[Sam Morgan]

Mike Short wrote:
> 25W. There has been several discussions this week about PSK output. Since it
> is a keydown mode PSK can be thought of as AM mode as far as power ratings,
> and so 1/4 of your rated output should be the max.  
>
so let me see if I have this right,
with a qrp K2,
that trips the high current indicator, when it's showing 9.6w.
it should be set to run about 2.4w (or less) on psk31?
--
GB & 73's
KA5OAI
Sam Morgan
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[Ken Wagner K3IU]

This bounced the first time I sent it to the reflector. Maybe it will
get through this time.
Ken K3IU

-------- Original Message --------
Subject: Re: [Elecraft] max power suggested on PSK with K2/100
Date: Sat, 02 Jun 2007 09:35:40 -0400
From: Ken K3IU <[hidden email]>
To: John Wiener <[hidden email]>
CC: Elecraft email email <[hidden email]>
References: <[hidden email]>



If you check the KPA100 manual (Rev E, anyway) you will find Elecraft's
position on this subject.

PSK31 - 40W
Other Higher Duty cycle, e.g., MFSK, - 25W

63,
Ken K3IU

John Wiener wrote:

> I just worked KJ5XF who suggested that running 50W PSK would fry the
> finals.  I thought 50 was about max for safe PSK.
> What's the latest on this?
>
> Thanks
>
> John
> AB8O
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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[k6dgw]

John Wiener wrote:
> I just worked KJ5XF who suggested that running 50W PSK would fry the
> finals.  I thought 50 was about max for safe PSK.
> What's the latest on this?

My KPA100 top got too hot to leave your hand on at 50W in a RTTY
contest.  I put a square of sticky backed velcro on it, the mating
square on the center of a 12V muffin fan, and now the heatsink stays
cool at 90W on RTTY.  I still run the K2/100 at 50W since I'm driving an
amp to 500W and need to protect it too, and at 50W, the heat sink is cold.

The heat transfer rate issue is still there ... the PA transistors will
be hotter than the HS ... but with the HS cold, the transfer rate is
increased a lot.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2007 CQP Oct 6-7
- www.cqp.org

PS:  The fan blows down onto the HS, but you all probably knew that.
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