[Elecraft] KPA1500 reduces power as it gets warmer?

[Ed Cole]

Disclaimer: OK the title is about the KPA1500; Elecraft advice probably 
extends to all their amps.  KL7UW

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"You should be running fans full-speed under those conditions if you 
want it to live long! "

Please share any data you have that supports any claim than running 
continuous full fan on any Elecraft amplifier has any advantage over 
letting the firmware control the fans based on PA temperature.
Andy, k3wyc
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If talking about CW, SSB, other low duty cycle modes that is fine, But:
Running digital modes that run "Key down" full output for longer time 
periods (eme cycles Tx=50sec/ Rx=70-seconds sometimes for for 
significant parts of a hour).  The safest procedure is to turn on fans 
full time.

Letting temp control logic control speed is also good (with Elecraft) 
but you are depending on reliability of more ckts.  What is the risk? 
How much to repair blown amp?
KL7UW

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It?s actually better than that. FT8 only transmits for 12.6 seconds 
giving a duty cycle of 42%. The 7.4 seconds left over are used for 
decode so you can have an answer to send in the next transmit slot.

73 Bill AE6JV
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Assuming you are running FT8 in 15-second sequencing. But FT8 can be run 
30-sec or 1-min seq, where Tx time is extended.  FT8 on HF or 6m using 
skip or sporadic-E, signals are probably strong enough for short receive 
sequences.  Not true if you are trying true weak-signal methods (example 
eme).  KL7UW

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The engineer that created the amp recently said that you should let the
amp handle the fans.? It should be in the archives here on this list.
W0MU
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OK, how much risk you take is up to you.  Regarding fan wear, I'm sure 
Elecraft chose long life-cycle fans (what is the MTBF?)

BTW does the KPA1500 display heat sink temp?  I add thermistors to all 
my amp heat sinks to real-time monitor temp.  The control board I use 
provides cktry for monitoring thermistor voltage plus auto-shutdown if 
temp exceeds trip point (or I can switch fans on, Full Time, bypassing 
the fan control ckt).

I operate eme 99% of the time.

73, Ed - KL7UW
Only Elecraft amp I own is KXPA100
the rest are W6PQL LDMOS amps