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RE: CFM and RQ Gaps
I may have been one of those who reported using no
airflow in the gap. I have a little enigma to mention in connection
with this - I reported this last year.
On 5 Jun 00, at 17:13, Tesla List wrote:
> Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
> When I was using an RQ/TCBOR cylinder gap, I tried both a 4.5"
> computer-grade fan and a vacuum cleaner motor, both drawing air through the
> gaps between the cylinders. Photos of the gap may be seen on my web site
> at: http://people.ne.mediaone-dot-net/lau/tesla/RQGap.htm
> I noted no performance difference between the fan and the vacuum cleaner
> motor, but performance plummets if the airflow is turned off completely.
> The 4.5" fans are typically rated in the 60-100 CFM range, although the
> actual number is highly dependent upon the back pressure. The effectiveness
> of the fan is also probably dependent upon whether the air passes through
> the gaps or just blows through the pipes. The CFM of the vacuum cleaner
> motor is unknown but many times greater than the 4.5" fan.
> It is also interesting to note that several well-respected coilers have
> reported that their gaps appear to work just fine with NO airflow. It's
> unclear if they tried it with airflow for a true with/without comparison.
The original configuration for the coil in question was a primary coil
of 3 turns (about 12uH), Cp = .1uF and a piffling 9" sphere as a
topload. This worked well with no airflow in the single 1/2" tungsten
carbide tipped gap. Any airflow tended to make firing erratic at best.
I was getting just over 4' strikes on occasions (dry days in
particular). Fr was about 156kHz if I recall.
Then I stuck on a much bigger topload and added a turn to the
primary to maintain tune. Fr dropped to about 130kHz, Lp increased
to around 18uH. Suddenly there were problems. The gap would fire
and power arc. Same setting, same cap and transformer. I tried
various amounts of airflow - again erratic or no firing and when the
airflow was low enough, power arcs re-appeared.
Then I got rid of the chokes (about 2mH worth) between the
transformer and gap. In this coil, the transformer has just a few
inches of lead going to the gap. Suddenly I got results with the
gentlest of breezes going through the gap. The setting is critical -
more than a mere waft and the gap is erratic or won't fire at all; too
little, and power arcs abound. The coil performs beautifully with
optimum airflow recording the occasional 5' strike. For the first time
I was worried about it hitting the lamps in the ceiling or the smoke
sensors. Note that the only real difference as far as the primary
went was a change in Xp and perhaps a little more coupling.
From all this I gathered that higher Xp's (read higher Qp) are
trickier to handle gapwise but lower gap losses considerably.