As applied to solid-state transmitters, ICAS does not imply reduced
device life, as unlike vacuum tubes, the RF power devices are not
regarded as consumables. Rather, ICAS in a solid-state environment
implies de-rating to keep the device junction and case temperatures
within their maximum ratings. Thus, ICAS suggests a limited operating or
'on' period followed by an 'off' or standby period of at least the same
or longer duration, whilst CCS assumes continuous, key-down operation at
reduced output (assuming the same heatsink area and/or fan air-flow
rating for both applications).
Typically, a PA cooling system should be designed to keep the device
case temperature in the range 70 ~ 80ºC (158 ~ 176ºF) at 25ºC (77ºF)
ambient, for a 30-minute SSB voice transmission or a 5- to 10-minute
“key-down” CW transmission at rated output. These are minimal duty cycle
values for an amplifier operating in average amateur service. Longer
“key-down” intervals, necessitating larger heat-dissipating surfaces and
greater air circulation, are required for contest operation or at high
ambient temperatures.
73
Bob, K4TAX
On 1/21/2016 8:44 AM, efortner wrote:
I would like to know what the continous keydown power output rating is. The
manual talks about ICAS. I know when I get on RTTY I does not take long for
The fans to come up to full speed running 300 watts.
Earl, K4Kay
-----Original Message-----
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Nand
Kishore
Sent: Thursday, January 21, 2016 4:29 AM
To: elecraft
Subject: [Elecraft] KPA500 finals blown
KPA500 shut off with a bang while operating RTTY @300W.
Antenna is a steppir beam.
On opening the KPA500,found 2 ceramic? caps of VRF2933
adrift with underside of the said caps,black.
Have written to support.Is this the first time this has happened
in a KPA500?
73 and HNY,
Nandu
VU2NKS
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