[TowerTalk] Polyamide (Stauff) Insulator Clamps

[KD7JYK DM09]

On 3/23/2022 18:51, Dino Darling wrote:
> Throw one in the microwave and see if it gets hot.

A good test, strictly at 2.45 GHz, and, the clamp is the only load in 
existence, relative to the RF source.  Test at actual operating 
frequency, conditions (antenna, frequency, atmosphere, relative physical 
surroundings, et cetera), and power. Just like PCB material, one needs 
to test at the precise operating frequency, or range intended for use, 
power level, and operating conditions, as a complete load in one range, 
may not exist at others.

Polyamide (nylon) is hydroscopic, absorbing moisture out of the air by 
its mere existence, and will no doubt briefly get warm with a kW at 
2.45GHz shoved into it, much like a cup of water, but 50W at VHF, and 
anyone other than the bureau of standards in unlikely to have the 
ability to notice.

The notion of adding a cup of water to the microwave during such tests, 
is also severely flawed, by additionally adding a more suitable load to 
the chamber, than the device under test, so even if testing at a kW at 
2.45GHz, the result is irrelevant, unless the test was to see if water 
gets warm in a microwave with some other tiny piece of debris containing 
moisture related molecules in it, also in the chamber.

Depending on the design of your microwave, the water may save it, I 
don't recommend running a microwave oven without a suitable load in the 
chamber, I've seen very large arcs come off a magnetron, and move around 
in the chamber looking for a load, or suitable ground.

Also note, the ideas surrounding black polyamide, carbon in the plastic, 
et cetera, is more of a reactionary notion, than anything else, and you 
are more likely to have issues with ambient humidity, the proximity of 
leaves, bird droppings, a bug, a large rain drop, butterfly spittle, and 
so forth.

It started decades ago when someone said something along the lines of 
'Hey!  These have carbon in them!', and someone else said something 
like, "Carbon is bad, that's a load, and extra load in antenna = bad'. 
Like the microwave test, it's an almost entirely pointless, and nearly 
100% flawed idea that just won't die, sorta like the requirement of a 
1:1 SWR, not coiling co-ax, and "ground" being "ground", or maybe "ground".

Kurt