Mar 192013
 

My problem was when I worked in 40m ( with power over 40 watt) my the  TV (LCD) was started automatically start up and shutdown.

I tried with differend ways to solve this problem but the result it was disappointing. After lot of  hours studing I found the solution.

The Combined Braid Breaker and High-Pass Filter.

This device prevents HF signal currents from flowing down the inner or outer of the co-axial cable. L1 has a low reactance to HF or VHF signals, thereby bypassing the interfering current, whereas C1 and C2 have high reactance to HF and VHF, effectively locking signals to the receiver. L2 provides a further short-circuit (to HF and VHF signals) across the connections on the receiver side of the filter.

At UHF the conditions are reversed. C1 and C2 presenting a low impedance path to signals to the receiver and the impedance of L1 and L2 is so high as to be ignored. R1 is for static discharge protection of the outer braid.

L1 and L2 are 4 turns of 20 SWG. 6mm inside diameter. 6mm long.

C1 and C2 are 4p7 disc ceramic capacitors.

R1 is 1M5 0.5 watt carbon resistor.

The PCB is single sided, 25mm by 50mm with grooves approx 1.5mm wide to leave four areas of copper as shown.

The filter should be housed in a suitable aluminium case with one side connected to the aerial downlead and the other side connected to the TV aerial socket.

 

 19/03/2013  Posted by at 4:29 pm Projects  Add comments

  2 Responses to “Problem with TVI interference”

  1. Kalo kai aplo to kiklomataki. Na to kouventiasoume kai apo konta giati ta agglika mou den voi8oun poli.
    73 Mixalis (ano glifada) you know..

    • Είναι όντως απλό και έχει απόδοση. θα τα πούμε απο κοντά

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