Thank you Bob, getting some actual numbers helps... I cut off
operations at 70C. In fact, if it starts getting above 65, I will
terminate ASAP. Knowing it could get to 90C makes me feel a lot better!
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 12/2/20 1:25 PM, Bob McGraw K4TAX wrote:
While I don't often run RTTY, I do run a good bit of PSK-31, WSJT-X FT-8
and MSK-144 along with CW and SSB modes. I do watch the PA temp,
specially as it nears 65 to 70 degrees C. I also run with the Fan on
#1 or #2 for starters. I know some will say it doesn't make a
difference while others say it will. As to me, I know that heat is the
downfall of solid state electronics. Cool is always better.
For the above, I normally run 400 to 500 watts, depending which power
indicator I choose. And, a very important point, at any time I never
exceed 500 watts into a well matched load. I do have a Bird 43P with a
500 watt, 2 - 30 MHz, element in-line between the amp output and ATU
input. I also have a 500 watt element, 25 - 60 MHz, for 6 meters.
Two facts to which I view one must pay attention: {per the KPA500 manual}
(a) Duty Cycle a 500 watts = 10 minutes key down / 5 minutes standby
(b) Heat Sink Temp = 90°C Maximum {194° F}
I view if one exceeds either of these two items above........they just
became a very underpaid design and test engineer.
73
Bob, K4TAX
Message: 1
Date: Wed, 2 Dec 2020 08:36:54 -0800
From: Dave Cole<d...@nk7z.net>
To:elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500/KAT500 and RTTY
Thanks sir...
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 12/2/20 8:24 AM, Gordon LaPoint wrote:
Dave,
I have done many RTTY contests and regular qso's using the
KPA500/KAT500/K3 over the last few years. I run full 500 watts with no
problems, the temp gets up to the 60 to 65 range a lot when calling CQ
in a contest, or during a 10 minute tx.? If the temp gets to 70 then the
fan kicks into high gear and is very noisy, but still within specs.
Gordon - N1MGO
On 12/2/2020 9:57 AM, Dave Cole wrote:
Hi,
Any recommendations as to the max power I might run using a KPA500 and
KAT500, on say, a three to five minute transmission?
Also, what is the recommended max temp for the PA on this device as
measured by the KPA500?
_
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