Re: Help w/ Big Tube Coil
Sent: Thursday, July 17, 1997 4:22 AM
Subject: Re: Help w/ Big Tube Coil
In a message dated 97-07-16 03:50:00 EDT, you write:
> Wow, what a great suggestion and an informative post!
> When you said "lower part of the primary form" did you mean that you place
the >feedback coil under the primary coil? Over or under, does it make a
> Do you have any suggestions on finding/pricing mica transmitting caps?
> Jeff W. Parisse
> Art Director, Digital Design Laboratories
> www.ddlabs-dot-com 1-800-796-1138
Yes, I do place the feedback coil under the primary form. This gives
two advantages; the secondary can be lowered below the primary for
very tight coupling experiments, and the top of the secondary can be
farther away from the other coils which helps prevent flashover.
I haven't seen any real performance difference with feedback coil over
or under the primary.
I buy my mica caps at hamfests for anywhere from 25 cents to 5 dollars
each, but they're getting very hard to find. Other types of capacitors such
as polyethylene are very good, doorknobs can be used, but they heat up
and go bad in most cases, I'm told. The micas are sold from some surplus
houses, I believe, but they may want $20 or so? New they're about $150
or more I believe?
Good luck with your coil, looking forward to your results.