Hi Dan, That may be why the ammeter burned out... :)I didn't have a scope and wideband CT when I had the 6" coil. In fact, I didn't even know that wideband CT's even existed until years later... :)
I did measure peak secondary base current with a Pearson wideband CT and Tek scope on a 10" coil a few years later. Base current pretty much matched theoretically-predicted current. This was long before the excellent simulation models and tools we have today. Then, all we had was basic TC theory, Conservation of Energy, and Excel spreadsheets. Comparing primary bang size versus secondary peak current, and then back-figuring peak secondary energy, I found that about 85% of the primary bang energy made it to the secondary during by the peak of the first ring-up when P:S coupling (k) was about 0.2. So in that sense, agreement was pretty good.
Bert Daniel Kunkel wrote:
Thanks for the info Bert. Did you find that your actual base current was close to the predicted current (5a seems kinda low based on the numbers from JavaTC on some medium sized spark gap coils). On Tue, Jun 25, 2019 at 1:37 PM Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx> wrote:Hi Dan, Many years ago, I tried using an older thermocouple type RF ammeter (that I got at a hamfest) in series with the secondary base ground circuit in a 6" coil. As I recall, it was a 0-5A unit. It worked quite well at lower power levels, but I accidentally burned it out when trying to run it at slightly higher power levels. The resistance/heating element in the meter apparently was a bit fragile, particularly when trying to handle the high-current peaks from a spark-gap TC. YMMV... I had much better success using a wideband current transformer and oscilloscope. Bert Daniel Kunkel wrote:Hello list, I have been thinking about using a current meter to monitor the base current of the secondary coil, mainly as a tuning aid. It appears thereareHAM radio guys that use RF ammeters, and there are even plans to buildyourown, however, I wonder how accurate it would be (due to dirty EMI and irregular current draw)? Has anyone tried this? Or is there a better waytoensure the tune is spot on other than observing for best streamer production? Thanks, ~Dan Kansas City area...where the ground might be starting to dry out, butonlya little bit _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla
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