Topband: RIG PROTECTION FROM BEVERAGES

[Rik van Riel]

On 01/16/2013 10:22 AM, Wayne Willenberg wrote:

> I have been looking on the Internet, and one possible solution is Array
> Solutions Model AS-RXFEP, RF Front End Protector.  The advertising claims
> to protect in the feedback situation as well as in a lightning situation.
> The insertion loss is claimed to be only 0.3dB.  For only $55 this seems
> like a good investment.  Does anyone have experience with this unit or
> would you please suggest an alternative?

You can build a near-equivalent to this yourself.

You want two series of 4 or 5 schottky diodes between the
signal and ground, in opposite sign to each other. This
limits the maximum voltage across the radio's signal input
to 2V or so.

Secondly, you want to limit how much current flows through
the diodes, so they are protected. You can do that by having
a 5 to 10 ohm resistor in series with your signal, between
the beverage antenna and the point where you have the diodes
to clip the signal.

That will limit the current to a small enough amount that
the diodes should not get damaged, and the voltage should
not go up just because there is a higher current flowing
through the diodes.

If you want to protect this circuit from higher potential
discharges (eg. nearby lightning strikes), you can always
put a TV coax gas discharge tube protection device between
your the antenna and diodes+resistor circuit.

Another solution is to have a relay that switches your
beverage in and out, based on one of the signals put out
by your radio when it receives (or transmits). Chances
are the amplifier or transverter control port on your
radio will have a suitable signal.