B
Bill W6WRT said:
>> In my case, a typical CQ macro will transmit for about seven or eight
>> seconds and listen for about 1.5 seconds, a duty cycle somewhere around 80%.
>>
Ah! good info Bill. Yes this is much more severe than my proposed 50%
worst case duty cycle. (i'm not sure my dummy load can handle that duty
cycle for long...)
I might try that duty cycle it at 1200W for a comparison to see what
temps rise to within 3 minutes. The short term comparison might point to
a reasonable long term comparison.
Don't think I'll try that duty cycle for long though.
My AL1200 has a glass chimney which pretty much causes the tube exhaust
to duct vertically to the drilled holes in the chassis cover.
One could debate the drilled holes. A cutout with a sparse grille would
have less obstruction. (like you see on PCs).
Same think on intake.
your other questions/comments:
My 30 minute repeating CQ test was for 30 minutes. approx 7 second CQ
macro. 6 second delay between CQ's. 1200W indicated. 3500V plate, tap at
245v, my supply voltage is a little under 240v. 3200v plate while
transmitting.
re "net" duty cycles
"Therefore, if one is for example, ragchewing, where you talk half the
time and the other guytalks half the time, the net RTTY duty cycle would
be 50%."
I don't think it's that simple. You can't average over arbitrarily long
times and say it's 50%. My point was that my macros limit max ON time to
maybe 7 seconds.
The max ON time, as well as averages over short and long periods, are
important for understanding what causes things to melt.
Like I would never do 1 minute ON, even if OFF for the next 3 minutes.
-kevin
ke6rad
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