Cecil Moore wrote:
Bill Turner wrote:
You didn't give many details such as the bandwidth of the antenna, but
if you use the NP0 type ceramic capacitors you should be ok. Loops,
especially small ones, are notorious for narrow bandwidth and stable
caps are a must.

I once used disc ceramic bypass caps to try to tune an
antenna. They went up in flames. For a small loop, I
would at least use doorknob quality caps.
I would also look for RF caps with a KVAR ratings.

Most caps even doorknobs are just simple HV power supply doorknobs with
no RF ratings. Ebay is full of this stuff, most of them are useless at HF.

Many of these caps have a resonance dip in them. I have found many that
dip at 7,8 and 13mhz. When i applied power you can figure out what
happened! So check them with a dipper. Good caps like HT57s will have
no dips. Some of the Russian pancake types are also good, but most are
GP high voltage caps for laser power supplies.

The ultimate caps are Tubular Types made by people like Morgan, however
they would make wire antenna with caps as expensive as a Steppir!
I was lucky enough to find a few of these for cheap and used them on a
N6LF type improved zepp antenna. These caps were rated at 50 KVar.
Someone told me 1kvar is about a kilowatt.


Pat