05-10-2023, 08:18 AM
(This post was last modified: 05-10-2023, 08:19 AM by Mike Watterson.)
(05-10-2023, 05:58 AM)AmadeusMozart Wrote: The ratings on most automatic ATU's are for SSB or CW duty cycle (50%) and then there is also the listening 50% of the time. Hence if there is a continous data transmission they may only be capable of something like 30% of what their "official" rating is.
I think it also depends on type and amount of mis-match. The current and voltage on each of the parts, which is often more critical for the capacitors rather than transmitter power. The coils and switch contacts are mainly limited by current. Obviously the "finding a match" (aka "Tuning") phase needs to be done at the lowest power that system needs for measurement to work, especially to avoid stress on the relay contacts, apart from not annoying other users of the frequency.
The T1 seems tiny but certainly isn't going to "wear out" on a QRP rig (5W) as it's rated at 20W. The FC-40 seems huge and internally not as cramped. Even knowing the ratings of the capacitors doesn't tell you what the power handling really is, but you tend to get catastrophic failure of the capacitors and they are easier to source and replace than the coils or relays.
Capacitor failure in the base seems to be the most likely failure of multi-band VHF or VHF/UHF whips/base verticals, though corrosion can be an issue.
