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Spark gaps

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LAN_403

HV Enthusiast

Mon Jan 05 2009, 12:13PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

cduma wrote ...

When someone tells me to research a topic on the internet that means to post your question on a forum to seek other peoples expertise.

True, but don't ask about a question that can easily be looked up using GOOGLE or a forum archive search engine. At least take the time showing you did *some* work first. More often than not, the responses you will get here will simply be links to old forum threads, or websites where a member will do the GOOGLE search, so in a sense, your post just reads as being "lazy."

To make a good impression, state you have looked at these websites, etc... (post links) and have looked at this particular design, and then follow that with specific questions to that particular design. Instead of just a blanketed request. We'll be more than happy to help you out at that point.

quicksilver

Wed Aug 25 2010, 12:56AM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I have a question & did not want to start another thread because this coincides with the subject matter.
On a SGTC I experimented with a 5-gap SG wherein one was of equal width apart while the other had (obvious both) descending or ascending widths. When using the GS where the gaps were of non-equal lengths I noticed an increase in performance (in that instance the noticeable change was an ascending width).

The difference I noticed were marginal but they were there. The streamers were a bit longer and appeared hotter.

When the voltage across the spark gap electrodes becomes suitably high is it possible that a smaller gap would allow for a more pronounced avalanche result to take place? Would there be an advantage to maintain the consistency of the gap or to use and ascending placement? Am I creating problems by doing this; as a greater level of ionization would "eat away" at the copper conductor?

Herr Zapp

Wed Aug 25 2010, 01:32AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

quicksilver -

In your informal test, spark gap "A" gave SUBJECTIVELY better performance than spark gap "B".

So, questions would be:

1. How can you remove the subjectivity from your test ("........appeared hotter........", etc). Carefully test the maximum arc length to a grounded target, over a reasonable period of time, for each gap configuration. You might also place an RF ammeter in your secondary ground line, and measure secondary base current. Provide time for transformers, capacitors, spark gaps, etc to cool completely between test runs.

2. Are you ABSOLUTELY sure that the TOTAL gap length of all gap segments was EXACTLY the same in each test? This perfect gap adjustment is not easy to achieve in a multi-gap setup. A small difference in total spark gap length can make a significant difference in in gap breakdown voltage, which can make a large difference in the amount of energy the tank cap dumps into the primary at every firing.

3. Did you clean all surfaces of your spark gap electrodes between each test, so that each test started out with the same level of oxide on the arcing surfaces?

The only way to get valid test results is by very carefully controlling all factors that might affect test results, and making sure that only one variable is changed.

Regards,
Herr Zapp

quicksilver

Wed Aug 25 2010, 05:59PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Thank you very much for a rather in-depth reply.

The subjectivity is a considerable flaw in my questioning in that obviously I didn't take into consideration: "reality over cursory observation". This I shall do via appropriate RF meter & it's result before rephrasing this issue & provide accurate measurements.

In regards to cleaning surfaces: I was careful to consider that (& this was done).

The question of measurements of gap electrode distance IS a really difficult agenda. I used a machine-shop gap-tool, however to maintain the measurement's integrity IS a real pain in the ass.

I get your point big-time! This frankly throws a monkey wrench in the whole affair.
The SG measured with the tool I had at an ascending level; but what if two were so close via a mis-measurement that it really only provided for a slight widening of the SG during a time when visually the streamer gave a false impression of higher brightness, etc?

I will have to professionalize the test medium to the best of my ability prior to offering really useful information......The flaws become all too obvious in your query.
However, for sake of observation; it did give me enough pause to make me wonder.
Another issue is that since I live in a rural area here could be variables beyond my control (i.e. voltage spikes - we have poor delivery of power, extensive lightning, aged transmission lines, etc.

You've given me a great deal to organize before the question could have greater bearing on construction principals.

radiotech

Wed Aug 25 2010, 06:58PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

You have mentioned experiences with a segmented arc. This may be of use. Wireless used arcs for years before valves were brought into use and for quite some time afterwards. It seems to me that much factual engineering was done. Here is some info. This is one of the ranges of arc systems found in Admiralty Handbook on Wireless Communication (1925) Recall that Telsa invented certain improvements in wireless. Let me know if you want scans of other arcs.

Jiffycoil

Wed Aug 25 2010, 07:19PM

Registered Member #2524 Joined: Wed Dec 09 2009, 06:29AM
Location: Johns Island, South Carolina
Posts: 23

EastVoltResearch wrote ...

As Dr. Spark said, try looking through the archives at

Just search for "static gap" and you'll find tons of old, yet valuable threads on how to make a static gap.

I'm still using the archives for info on building SSTC. It may be awhile before I can ask a question that hasn't already been answered. The power of what's been done here by many of you is a wealth of knowledge.

quicksilver

Wed Aug 25 2010, 08:42PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

radiotech, I deeply appreciate you taking the time and putting up those scans. That is not only fascinating but it gave some pretty interesting ideas......
Thanks for the "leg up".

Herr Zapp

Thu Aug 26 2010, 12:03AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

quicksilver -

Jeff Behariy's Electrotherapy Museum website (

) has a lot of information on early spark gap designs, including various styles of multi-segment quenched gaps.

See

for some specific info, but spend some time looking through other sections of his extensive website and you'll finds lots of information on spark gaps.

Herr Zapp

quicksilver

Thu Aug 26 2010, 03:24PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

EXCELLENT! - Danke Mein Herr.

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