On 6/2/2014 7:55 PM, Richard L Diddams, Sr. wrote:
My comment is not to K6GPW, but to the continuously number of postings regarding Fan Noise.
Far more than necessary, IMO. Dick, the fan speed is adjusted by the control system based on temperature of the output devices, which you can monitor from the front panel. The fan speed gradually increases as the temperature passes lower temperature thresholds, but it really kicks into high gear at about 71 degrees C.
If you want to hear what this sounds like, put a brick on the key and crank the amp to rated power for a minute or so. Depending on ambient and air flow in your shack, you'll hear it kick in, and if you have the instrumentation to do so, can measure it yourself.
My fan kicks in roughly 40-45 seconds into a keydown transmission on 6M, and very occasionally, briefly, when I'm RTTY contesting, calling CQ near the end of the contest with few responses. In normal contesting, where you're sitting on a frequency and running stations at several a minute, the duty cycle is low enough that the high fan speed rarely kicks in.
Could the noise level be reduced by some design advice from a good acoustic consultant? Sure. I can recommend several who work on making HVAC systems in theaters and concert halls dead quiet. How much cost would you like to add to your KPA500?
The sound pressure level at that high is nothing more than annoying, certainly nothing to be alarmed about from a hearing damage point of view, and it's a lot less annoying if you're wearing cans. And for keydown modes like AM, FM, PSK, and RTTY, there's even a side benefit -- when the fan speeds up, you've probably been going on too long about nothing, so it works to prevent you from boring the other member(s) of the QSO.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
