"Michael Fox \(N6MEF\)" <n6mef@...>
The May 14th UDRX update on the blog page says: “… goal of 100% duty cycle in a 20C shack without a fan. A separate temp-controlled fan kit will be available for high ambient temperature, continuous duty applications.”
A couple of issues there:
1) 20C is 68F. That’s pretty chilly and not something that will realistically be found … almost anywhere. So higher than 20C is not exactly “high ambient temperature.” For example, we know from experience that the temp at most radio sites is in the low 70s to the low 80s (22C-30C).
A more common temperature spec for equipment is 40C. My laptop is rated at 0C – 40C. Many industrial/automotive fanless PCs are rated at 40C. Industrial SSDs are commonly rated at 40C. And, when an A/C failure happens, the indoor temp at a radio site can easily reach 100-105F (38-41C) or even exceed that (109F/43C was the highest I’ve ever seen). So 40C is a much more useful number.
2) 100% duty cycle doesn’t tell me much about how the device will perform in real-world applications. Specifically, most applications will involve some TX, some RX, and some idle time.
So, I’m thinking that a more useful set of specs would be to tell us the max sustained temp tolerance for a few different duty cycle options, both with and without the fan. For example:
100% TX, no fan: 20C
100%TX, w/fan: ??
50% TX, 50% RX, no fan: ??
50% TX, 50% RX, w/fan: ??
33% TX, 33% RX, 33% idle, no fan: ??
33% TX, 33% RX, 33% idle, w/fan: ??
That should be enough to help us understand whether we need the fan or not for our situation, as well as whether it will withstand typical radio site environments.
BTW: I hope the fan option will include a filter. Many mountain top sites can be dusty! A simple 1/8” thick foam filter like is found in a window A/C unit or many industrial PC would be perfect.