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Re: Tank circuit noise etc.





Hi Terry,

I hope the info about my spark gaps proved useful, although I think they
are pretty common.

Your point about hitting an IF frequency of the TV receiver is very
interesting,  I will check what IF frequencies are used in UK
TV receivers.  Also I just threw my HV probe across the spark gap. 
The gap voltage was almost a square wave with hardly any decrement
at all !

The amplitude was almost constant with only a slight curve to the tops
and bottoms of the waveform.  I think this proves that the voltage drop
across the gap is constant.  However there was serious RF hash at the
zero crossings,  and the tail end was very blurred.  My scope only goes
up to 20MHz and is not a storage type,  so I am sat in the garage in
complete darkness trying to see what exactly is going on !

I had a play about with Microsims PSpice today,  and managed to devise
a circuit which gives:

1. A linear decrement,
2. An initial VHF burst,
3. Slight zero crossing bursts.

I dont know if this model is valid but I can send it to you if you
want.  

Keep up the great research,

						Richie.