[NLRS] SMA power handling

[Dr. Gerald N. Johnson]

 From a 1983 Amphenol book dedicated to SMA and SSMA microwave connectors:

Maximum operating voltage peak 500 volts with UT141 and RG58 family 
coaxes. But that's not a power limit for a matched 50 ohm load.

I've not found any mention of power handling rating in this catalog.

Power rating of RG-58 is 150 watts at 146 MHz according to my 4th 
edition ITT Reference Data for Radio Engineers, page 616. Notes to the 
graph say its based primarily on an 80 degree C maximum operating 
temperature of the center conductor in easily melted polyethylene 
insulation. But they recommend a maximum temperature of 65 C and for a 
40 C ambient a power rating of 59% that of the graph or 88 watts. The 
data was derived from MIL and RETMA standards.

Teflon versions including UT141 should stand a little higher power from 
silver plated conductors and a greater tolerance for heat. The true 
power limit (and Amphenol doesn't seem to set a power limit) comes from 
dissipation of losses in the components and connections. Some offshore 
produced SMA seem to have conducting parts made of thinly gold plated 
steel and much higher losses than good connectors. I plan to dig into 
those after I identify the nasty ones with RF tests to see just how they 
have made them bad. I plan to cut the bad ones open to see just what is 
inside. The male part of the SMA is essentially that of a bit of UT-141, 
in fact some males are exactly that, the connector is just the threaded 
ring and a sleeve to anchor it to the coax. So the maximum power an SMA 
connector can handle can't be greater than what UT-141 or RG58 can 
handle. the parts are in the same proportions and heat dissipation in 
the connector is greater because of contact resistance.

73, Jerry, K0CQ

On 2/15/2013 8:58 AM, w0zq at aol.com wrote:
>
>
>
> Assumming a good match, how much power can a SMA connector handle at 2m, anyone know?
>
> 73, Jon
> W0ZQ
>