[Waverley ARS] RF fuse

[George Georgevits]

Hi Edwin,

> I have always simply disconnected my aerials from the back of the
> rxer/txer, but it's a real pain.  I didn't think that simply turning a
> coax switch to an unused position was enough protection, in case the
> static surge would arc across the switch to the radio.

If you are not using an aerial which has some part of it grounded (eg. a
dipole), you should have installed a bleeder resistor (eg. 100K, 1W) from
each leg of the feeder to ground to ensure that there is no static buildup.
This is regardless of surges, which are a different matter.

Also, turning the switch to an unused position will give you many kV of
isolation, which should be more than enough.
>
> Also, why a knife switch for HF aerials?  That's fine if using
> twin feed or a long wire, but if HF is being fed with coax, wouldn't a
> coax switch work the same way?

At HF, it doesn't matter. You can use a knife switch on coax without any
noticeable degradation in performance. Technically, this is because the
transmission line discontinuity caused by the knife switch is very small,
due to the very small fraction of a wavelength it represents at your
operating frequency.

Hope that explains it.

de VK2KGG