[Elecraft] KPA-1500 Fan Noise - measured (sort of)

[Chris Codella, W2PA]

In an attempt to quantify this, I installed OSHA's free NIOSH app, which 
measures noise, onto my iPhone 7 and tried it out.  It's not a 
measurement instrument, mind you, so the absolute numbers are highly 
questionable.  But the relative numbers are interesting.  I held the 
phone at eye level between me and my computer monitor, about 2 feet from 
the amplifiers.  Here are the results:

dB measured with NIOSH app, rounded to two significant digits:

46 - for comparison - an Alpha 89 running as normal
48 - KPA1500 at fan level 0 (i.e. PS fans only)
51 - fan level 1 (i.e. center fan plus PS fans)
57 - fan level 2 (all fans on)
64 - fan level 3 (all fans on)
67 - fan level 4 (all fans on)
76 - fan level 5 (all fans on)

Similar to other comments I've read, I find up through level 2 to be 
okay.  At 3 and above I need headphones or, better still, noise 
cancelling ones.  My experience thus far is that on SSB in normal 
conversation at 1500W it stays at level 0 with an occasional excursion 
into level 1 if I'm long winded.  In the CW WPX test last weekend, 
strictly in S&P mode, it stayed at level 0. Experiments with CQing and 
on FT-8 are yet to come and I'm sure will require higher speeds.

73,
Chris, W2PA