Re: [TCML] Terry filter quick questions

[mddeming@xxxxxxx]

Hi Jay,

Terry filters are most usually used with NSTs and OBITs because they are the types of transformers most vulnerable to HF/RF damage. They can of course be used with other types of transformers, but are not needed on over-built types like pole pigs. For intermediate types, it's almost a personal call as to how needed a filter is. (Does a HUM-V NEED rubber bumper guards?) Just be sure that the thruput parts of the structure (busses, etc.) are beefy enough for your power thruput.

Matt D










-----Original Message-----
From: jhowson4@xxxxxxxxxxx
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Thu, Jun 3, 2010 10:11 pm
Subject: Re: [TCML] Terry filter quick questions


Woops, that 1000K was supposed to be a 1K. 
Alright so the resistors are needed for the operation of the filter, and it 
ooks like I need to find some 1K ones. 
One thing I am confused on that seems to pop up regularly on the internet, is 
hat terry filters are not intended for anything except NST's 
hy is that? is it not possible to apply the same principles to regular 
ransformers such as a PT, with a slightly modified circuit? 
hese guys seem to be doing what I am talking about with a PT. 
ttp://www.tb3.com/tesla/teslathon2003/tb_tc/tb_tc.htm 
ny one have a schematic for what they are using? 
Gary..Great site. Thanks 
Thanks again , 
ohn "Jay" Howson IV 

---- Original Message ----- 
rom: "Gary Lau" <glau1024@xxxxxxxxx> 
o: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> 
ent: Thursday, June 3, 2010 8:52:30 PM GMT -05:00 US/Canada Eastern 
ubject: Re: [TCML] Terry filter quick questions 
1) If both wire-wound and film resistors were available with 
omparable ratings, I would choose film, but I don't think I would be 
ble to justify that, analytically. Since 100W film resistors are 
ather uncommon, wire wound units are commonly used. 
) The resistors, in combination with the caps, form a low-pass R-C 
ilter, to attenuate VHF high voltage transients from getting to the 
ST. The resistors without the caps would not do this; the resistors 
ust be used with the caps. The long story if available on my NST 
rotection circuit web page: 
ttp://www.laushaus.com/tesla/protection.htm 
) The recommended resistance is 1000 Ohms or 1K Ohm, not 1000K Ohm. 
 100 Ohm resistor would not be effective, and a 1000K (1Meg) resistor 
ould waste more power than it passes. 
Regards, Gary lau 
On Thu, Jun 3, 2010 at 8:01 PM, <jhowson4@xxxxxxxxxxx> wrote: 
 Hey guys, quick question on terry filters. 
 
 1) Are wire wound or film resistors preferred 
 2) What exactly is the purpose of those big resistors . 
 3) Is the 1000Kohm rating imperative? I have some 100W 100ohm resistors...Will 
hese work? 
 
 Thanks in advance, 
 John "Jay" Howson IV 
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