They work ok but will show up on a good res time domain reflectometer or
keen oscilloscope at 150 mhz. I can tell a barrel splice from a 30-50-30
squiggle on the tape or screen wherever it is on the line. I would think any
vhf/uhf work would be fine until you turned the wick way up. I knew a fellow
that ran an 8877 HB amp with one into a perfectly flat 50 ohm load for hours
on end in repeater operation. I think my point was high power and high
frequency may not be their strongest attribute and that when surprises
happen, they happen fast, in a flash so to speak and may take a tube or
bandswitch with it.
Sam
-----Original Message-----
From: Carl [mailto:km1h@jeremy.mv.com]
Sent: Tuesday, April 26, 2011 5:04 PM
To: Sam Carpenter; 'Steve'; amps@contesting.com
Subject: Re: [Amps] Power handling of an SMA
A 30 Ohm connector that is 1" long will not even show a bump thru at least
6M and they are still OK on 2M.
Some UHF articles have stated they are a perfect 50 Ohms at 1296, dont
know.I use them at low power on 2M FM gear including the 400W PP 4-125A FM
amp for contest into an old commercial 22' collinear.
Carl
KM1H
----- Original Message -----
From: "Sam Carpenter" <sam@owenscommunication.com>
To: "'Steve'" <g8gsq72@gmail.com>; <amps@contesting.com>
Sent: Tuesday, April 26, 2011 1:07 PM
Subject: Re: [Amps] Power handling of an SMA
> As your figures from Suhner shows, .5kw is all I will do with an N at 800
> and up. I think you find that with DB Spectra, Celwave, Andrews and other
> makers of filters in that range. It is pretty standard. I too agree on the
> Suhner product. I use them when I have RX tower top preamps 500' up a
> tower
> for emp protection. They use gas plugs that fire reliably and are easily
> replaced without taking arrestor out of line. As for the PL259, it was
> designed as a DC Connector on boats and is not typically 50 ohms. When I
> run
> a TDR Sweep of the line, they show up as 30 ohm connectors most of the
> time.
> It does at least make them easy to identify from the ground on a new site
> because the stick out like a sore butt on a monkey on screen.
>
> Sam N9FUT
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Steve
> Sent: Tuesday, April 26, 2011 12:04 PM
> To: amps@contesting.com
> Subject: Re: [Amps] Power handling of an SMA
>
> Suhner data shows approx. 500W based on dielectric strength, but there's
> a second 'low SWR' curve on the chart which extrapolates to around 1500W
> at 1.3GHz. The spec. also gives 10kW for 1us. The contact resistances
> are listed as a few milliohms, so you'd be looking at 10s amps to create
> significant heating.
>
> Not all SMAs (or other connectors) are created equal. I handle many
> brands of connector; I reckon Suhner are consistently the best quality,
> and that's not pro Eu/anti US bias :-)
>
> UTI rate .141" coax for 300-400W at 1GHz, depending on the materials and
> plating. This will push the cable to max. rated temp., 125 or 150C I
> think, so might be more than you'd choose to run if you don't want to
> burn your fingers.
>
> Steve
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