Re: chokes (fwd)
---------- Forwarded message ----------
Date: Sun, 24 May 1998 19:42:56 -0600
Subject: Re: chokes (fwd)
I use two (one in each neon leg) 10K 25W wirewound resistors from
DigiKey to isolate the secondary from the neon and such. I have tested
these and they work find at ~300KHz range. They will also definitly damp
any LC oscillations from the chokes which is very important. Otherwise, the
noen my be harmed or the gap won't quench well.
Finding the power dissipation is straight forward. For a 60 mA neon
and a 10K resistor: P=I^2 R ---> 0.06^2*10000 = 36 watts. I run them a
little hot :-)
At 09:56 PM 5/23/98 -0600, you wrote:
>---------- Forwarded message ----------
>Date: Sat, 23 May 98 16:38:38 EDT
>From: Gary Lau 23-May-1998 1623 <lau-at-hdecad.ENET.dec-dot-com>
>Subject: Re: chokes
>>From: Mad Coiler <tesla_coiler-at-hotmail-dot-com>
>>Subject: Re: chokes (fwd)
>>>I would recommend dumping the chokes and using 300-500 pF bypass caps
>>>with series resistors and safety gaps on each side of an NST.
>>Assuming for the moment that I do as you suggest: I have a bag of 1nF
>>6kV ceramic caps that I could series for use as bypass caps. What kinda
>>resistor values we talking about? What V rating for the caps should I
>>need? Are you grounding the center of the bypass cap network or just
>>going from terminal to terminal on the NST's?
>>Sorry so many questions but I am getting so many different responses
>>regarding the use of chokes. I think experimentation is going to be the
>>best way to figure what works better for my setup.
>Experimentation is great when the success or failure can be easily
>determined. Unfortunately with NST protection networks, success does not
>result in measureable coil performance, but in a longer life of your NST.
>It's hard to know you're doing the wrong thing until it's too late, and
>may be highly dependant upon the history and condition of the NST you're
>using :-( That's why there's such a lack of consensus on this.
>Your ceramic caps should do fine for bypass caps, I'd recommend sets
>of four in series, 24KVDC, with 1-2 sets of four (250-500 pF total) from
>each of the NST HV terminals to your RF ground. Safety gaps (~.25")
>should be in parallel with each bypass cap cluster. Then a BIG resistor,
>like 500-1.5K, 50-100W from each NST terminal to the main gap. I don't
>know why they dissipate so much power but they do, at least if your main
>cap is well matched to the NST and is mains-resonant to draw maximum
>Waltham, MA USA