Re: Magnifier system

To: tesla-at-pupman-dot-com
Subject: Re: Magnifier system
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
Date: Thu, 21 Nov 1996 08:23:48 +1200
Hi Dan,
          In reply....

>     First, whenever I'm determining the resonate frequency of a secondary I
> personally use 
> the grid dip method. Attach an "O" scope and RF frequency generator to
> the base with dischard 
> terminal attached (serial). Simply raise the frequency until the coil
> starts to draw max current.

Different method from mine but just as good. Might not be the best way
of measuring unloaded Q though.
 
>     Second, I'll use the same setup to tune my primary to the secondary by
> using a parrell
> setup and <SHORTING> my spark. Then keeping my RF generator at the
> resonate frequency, I'll adjust
> my primary tap until my primary draws minimal current. There by, both
> circuits are in tune.

I wonder about that. The resonator should be heavily absorbing when 
correctly tuned to the primary shouldn't it? I prefer to tune the 
primary to the secondary with no secondary present to get scope tune. 
Or is that what you're doing (measuring parallel resonance)? 

> And now the fly lands in the ointment!
> 
> In the obove paragraph I stated that the spark gap was shorted,
> there by I was able to obtain an LC oscillator with a frequency that
> will cause my secondary to resonate. But in operation, the circuit
> used is a Spark Inductor Capacitor variety. Spark gap circuits,
> also known as dampened wave oscillators, output multple RF
> frequencies while in operation. From this understanding come some
> questions that need to be asked.
> 
> a) How much wave dampening do these secondary frequency impose on the
> secondary, as its being excited
>    by the primary?

Virtually none, because the secondary being highly selective forces
unwanted frequencies to remain in the tank and the energy in them 
ends up contributing to the fundamental. 

> b) Would simply dividing the secondary into two parts reduce the above
> effects? 
> 
>     The base being few but large AWG(9) turns for capturing as much
> magenetic energy as possible and reducing the out of phase effects of
> the primary. Top comprising many turns of small AWG(30) 
> wire, to take advantage of the voltage rise due to inductance. And of
> course the split secondary's
> top part would have to be seperated by a distance that reduces the
> primary circuits influence. Therefore,
> the magnifier could be an attempt to minimize the amount of cross noise
> in a tuned resonate circuit.

To me the thing about transformer coupling to the base of the 
resonator should eliminate the frequency split one normally gets with 
DTC (over)coupling (I will be checking this soon). I think other 
spurious resonances generated by the primary decrement alone are (a) 
pretty insignificant in amplitude compared with the fundamental, and 
(b) are effectively squished by the selectivity of the 
secondary/tertiary.

Malcolm