Re: NST Shunt Removal (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 12 Jun 2007 19:20:27 -0400
From: otmaskin5@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: NST Shunt Removal (fwd)

Thanks everybody for the advice.  Sounds like heat is the only potential problem - which I gather can be managed with oil emersion & possibly tempurature monitoring.  I don't usually do very long runs anyhow - maybe a minute or minute and a half.  

I'm going to find a suitable container for the depotted NST & then I'll have a good idea of how much transformer oil I would need.  I'll contact you, Dr R, to order some - thanks for your offer.  

What does everybody usually use to contain an oil-immersed NST?  Tupperware type of stuff?  I assume a container slightly bigger than the NST would contain enough oil for sufficient cooling.

Thx again, Dennis Hopkinton MA


-----Original Message-----
From: Tesla list <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Mon, 11 Jun 2007 6:30 pm
Subject: Re: NST Shunt Removal (fwd)




--------- Forwarded message ----------
ate: Mon, 11 Jun 2007 18:01:45 -0500
rom: resonance <resonance@xxxxxxxxxxxx>
o: Tesla list <tesla@xxxxxxxxxx>
ubject: Re: NST Shunt Removal (fwd)

You can safely remove the shunts for much more power, up to 80% more current 
utput, if you drop the transformer into a tupperware or other suitable 
lastic container with transformer oil.  No, the higher current is not a 
roblem if the xmfr is protected in xmfr oil.  Heat is the enemy here.
Always use a Terry filter and a safety spark gap to prevent spikes and 
verpotentials.
If anyone requires xmfr oil for a project we stock it in 55 gal. drums and 
ould pump out a few gallons.
Dr. Resonance
This was brought up by another coiler in an earlier post, but I don't 
elieve anyone answered it. Does removing shunts make an NST more 
usceptible to failure, or is it a safe way to increase output? Thanks for 
ny advice, Dennis Hopkinton MA

----Original Message-----
rom: Tesla list <tesla@xxxxxxxxxx>
o: tesla@xxxxxxxxxx
ent: Mon, 11 Jun 2007 9:24 am
ubject: RE: NST Shunt Removal (fwd)


-------- Forwarded message ----------
te: Sun, 10 Jun 2007 18:33:34 -0700
om: Jim Mora <jmora@xxxxxxxxxxx>
: 'Tesla list' <tesla@xxxxxxxxxx>
bject: RE: NST Shunt Removal (fwd)
ello,
 too modified a France 12/30 removing half the shunts and potting it a
xture of melted Vaseline and paraffin. It arcs a Really hot flame!
im Mora
----Original Message-----
om: Tesla list [mailto:tesla@xxxxxxxxxx]
nt: Sunday, June 10, 2007 3:51 PM
: tesla@xxxxxxxxxx
bject: NST Shunt Removal (fwd)
--------- Forwarded message ----------
te: Sun, 10 Jun 2007 16:05:07 -0700
om: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
: Tesla list <tesla@xxxxxxxxxx>
bject: NST Shunt Removal
i All,
y 4.5" diameter coil spark lengths are far beyond a 12/60 NST capability.
tp://www.classictesla.com/photos/ba45/ba45.html
d these pics don't really show the lengths I've seen with this coil.
he NST I use was modified by fixing some hv windings and removing 1/2
 the shunts (back when I documented the NST depotting procedure. So,
e 12/60 Franceformer is no longer a 12/60. At the time, I never
nished the measurements on the NST. Well, I rebuilt my hv divider
day using 6 100Meg HV resistors (mfg p/n EX2G1006, $1.66ea). These are
de by Ohmite and good for 7.5KV each (I have 3 in series on each leg
r 22.5KV at 300Meg). Anyway, following calibration, I tested an
modified 15/30 Franceformer. All came out as it should. Here's the
ta for the unmodified 15/30 NST.
=0.8 ohms, Rs=16230 ohms.
PEN CIRCUIT MEASUREMENTS:
pri = 124.1 V
pri = 0.74 A
pri = 24 W
_pri = 91 VA
 = 0.27
sec = 15340 V
HORT CIRCUIT MEASUREMENTS:
pri = 124.0 V
pri = 3.83 A
pri = 39 W
_pri = 474 VA
 = 0.08
sec = 25.74 mA
nowing that the hv divider is working well, I decided to unbolt the
dified 12/60 and run it through both open and short circuit
asurements. Here is what I found: btw, Rp=0.45 ohms, Rs=4660 ohms.
PEN CIRCUIT MEASUREMENTS:
pri = 124.2 V
pri = 1.53 A
pri = 50 W
_pri = 190 VA
 = 0.26
sec = 13380 V
HORT CIRCUIT MEASUREMENTS:
pri = 121.3 V
pri = 20.3 A
pri = 428 W
_pri = 2457 VA
 = 0.18
sec = 206.7 mA
o, as you can see, this NST is no longer a 12/60, closer to a 13/200
d that explains the arc lengths being so good, or really, "not that
od" considering I am about 20" shorter than I should be for this power.
r. Resonance was wondering why the little coil was doing so well and
d asked me offline. I let him know the NST was modified, but I didn't
ve the data to give him at the time. I've probably pushed that NST to
e brink of saturation, but, it has held up well, it just keeps on
nning. It's reliability is a pleasant surprise considering what I know
ow" about the modifications.
 took out exactly 1/2 the shunts. I_sec jumped from 60mA to 200mA (more
rrent than I intended). I was hoping removing 1/2 the shunts would be
linear jump to 120mA, but that was just a shot in the dark. If I were
 modify an NST again by removing shunts, I would only remove 1/4 of
e shunts. 1/2 seems a bit much. This NST is more like a PT or
mbarder now. I really don't know how long it will last. Last week, I
st an XBOX 360 and my main computer (video section on motherboard
mmitted suicide). This was due to a small 2" coil that I ran without
 RF ground. Big mistake. However, my NST Terry Filter smoked with this
5" coil Thursday. The coil and NST still run great, but the Terry
lter has some burnt resistors. Looks like I'll have to check all those
V's!
ust thought this data might be of interest to anyone considering shunt
difications. I know those that happen to manage NST shunt removal like
e fact they have (more power, baby!), but not everyone makes the
asurements following the modification. And considering what I found,
2 the shunts removed might be stretching (or not depending on your
ew of things).
ake care,
rt


________________________________________________________________________
OL now offers free email to everyone.  Find out more about what's free from 
OL at AOL.com.




________________________________________________________________________
AOL now offers free email to everyone.  Find out more about what's free from AOL at AOL.com.