I never heard of arcing failures with properly mounted N connectors and
used with standard equipment and reasonable power, this not only with
Ham equipment but also in professional applications.
In the other hand, I've been reported and seen by myself UHF joints
that have failed, even at a relatively low power, because of bad
quality product or after the internal of connectors got contaminated by
moisture that penetrated directly, or drained inside by capillarity.
Obviously, recycled UHF connectors doesn't help to rise reliability but
it seems also this procedure is not rare.
> My AL-1500 when driven by a 775DSP put out over 5kW of pulse
> measured power on a good meter. That's almost CB radio type
> power levels.
I've some doubt about the 5Kw output pulse with an AL 1500, but let's
assume this number as real, by ipotesis.
If an N connector isn't enough insulated to withstand the voltage that
starts the arc in AL 1500, is it bigger the insulation of load
capacitor in AL 1500 amplifiers ? And interconnections made with RG8X ?
Measuring with an electronic caliper I find both N and UHF have an air
gap that's about to 0.1 inch. At 50V per mil, the stand off is 5KV and
the power formula is VxV/impedance. By voltage numbers an enormous peak
power capability would be possible, but allowable power is effectively
much less because limited by joule effects rather than voltage.
Back to the main thread, the difference is that N is in air along the
whole lenght while UHF is 98% of the lenght insulated with delrin or
steatite (rarely teflon) but not in the point where male and female
flat insulated parts faces, thus dropping the overall breakdown rating.
What happens in an UHF joint (cable included) that's not inherently
weatherproofed, doesn't press the cable or have been damaged by
overheating during installation surely doesn't help to keep the 50V per
mil of stand off.
Average amateur PAs in the > 1KW class (i.e L4B, L7, TL 922, SB 220,
etc. etc) have a variable (& fixed) load capacitors with an isolation
that's considerably less compared to an N connector.
Damaged plate capacitors by arcing in those amps are not rare events
but quite rarely the variables used as a load suffers troubles because
of excessive voltage, I'd say never in my experience.
> Now, where did that owl go? Did he head true north, to land on a
> Razor Quad or did he get his feet stuck in the rope in the vibrating
> element?
The guilty about the Owl problem could have been a contester meanwhile
trying to vibrate his antenna elements to see if that helps in heathing
the ionosphere.
73,
Mauri I4JMY
> 73, Tom W8JI
> W8JI@contesting.com
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