Re: MMC lead length and bends...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 08:39 AM 11/6/2006, you wrote:
> Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
> Hello Group,
>
> Has anyone ever taken in account the capacitor 
> lead length and bends in a LARGE mmc >300 .15uf 
> caps. If it is a non issue how are you 
> assembling the mmc short leads 3/8 spacing? I 
> was going to put a glass bead on both ends of 
> the cap, pass it through a lexan plate and 
> solder the resistor on the other side. And make 
> the connection to the next cap with a soldered 
> butt splice. The leads are making 2 right turns? 
> 18 rows of 22 each string .12uf total, 44KV. 
> That is lot of tiny inductors this method, yes?
> Furthermore, inductors in series are 
> additive-probably wholly due to the inverse 
> square law. Anyone have any ideas on this issue? 
> Or measured their MMC inductance? Iâ??ll bet its 
> a lot more then cumulative inductance of the 
> caps only. Someone please tell me Iâ??m fussing 
> over nothing; especially if itâ??s true â?º


I think you're worrying unnecessarily, unless you 
plan to be operating at 30 MHz or something.


ball park is that L is 1 uH/meter, so a 1cm cap lead is 10 nH or thereabouts.

You've got a string, of say, 22 caps, at 20 nH 
each, for a total of 440 nH.  But you've got 18 
rows in parallel, bringing it down to around 22-25 nH.

Considering that the leads from the MMC to the 
spark gap and primary are probably 1 uH alone, 
the incremental L from the leads isn't all that big.

And besides, L that's not in the primary just 
effectively reduces the overall coupling of the 
system, and since most TCs are somewhat 
undercoupled, you could just move the secondary 
closer to the primary to compensate.


> Best regards,
> Jim Mora