rx receiver protection

RF limiter for RX entrance to the station (20/01/2015)


When working with multiple stations simultaneously (eg. In an environment where it competes with several stations at the same time), can lead to very harsh signals to a receiving antenna (RX antennas) that are in the station priklučne through the RX input. Consequently, it could easily happen to us too strong signals or energy induced damage to the receiver or another part of the station.

We are looking for a solution to this problem and come up with the limiter RF or RF limiter. Uncle Google and other amateurs we were served with information and various schemes from which we have drawn on the base and a little matter further "pofrizirali".

The result was as follows: picture

Version of this circuit is formed to review existing RF Limiterjev K8ND (bulb), ICE RF limiter / reciever protector - ICE 197 RF limiter S59AA and in cooperation with Jure S57XX, Darko S57UUD and others. Thank you all for your support and cooperation!

So why such a circuit?

The lamp has a variable dynamic impedance. When, therefore, does not light has a very low resistance and, together with the diode represents the divider, which is the normal operation is made so as to have as little losses. Having too much energy at the lamp resistance greatly increases, thereby splitting ratio also changed so that the loss of large signals enormous. Versions without a lamp to my not be suitable if you have an antenna in the vicinity, whereas for large signals we need one "customer" who will, in addition to discharge energy to GND, the excess energy consumed.

In the original versions, were instead two LEDs used 4 diodes 1N4148. Using diodes 1N4148 in this circuit is somewhat problematic. These LEDs do not necessarily have sharp elbows, but have a non-linear characteristic in the field of low voltage. The binding is two in the series, this phenomenon is even more noticeable.

Even in the inverse direction to know how these diodes cause a problem called avalanche effect. This in turn means an increase in noise. How is this important to KV jeodvisno of natural noise, so maybe this effect would not even have noticed.

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Parts List

1K Ohm resistor
3-10n/1Kv Capacitor
light 12v/2W
4*Diodes 1n4148
1*90V/20kA (Gas Discharge Tube)

It makes sense therefore to replace all four diodes 1N4148 with two recent LEDs. The best choice would be the blue LED, because they have some higher threshold, and thus ensure that the signals to somewhere 1,8V without interference. (Text taken from s57uud).

I hope that someone will come in handy to protect their radio stations.

In short they made the first products, which we can also stestirali and criteria. lp