Topband: Penant - matching transformers?

N2TK n2tk@arrl.net
Sat, 14 Dec 2002 19:26:25 -0500


Finally got up my Pennant antennas. I am using RG-6 for feedlines. I had
some autotransformers, so used them to get things going. The antennas work,
so it's time to use the proper transformers. Trying to find out what are the
proper transformers. After searching the archives, I found the following
matching transformers:

- FT140-43 with either 9T/31T, 7T/24T, 8T/34T #26 wire, 10T/45T #30 wire
- FT114-77 with 4T/17T
- FT114-F with 5T/20T
- FT50-43 with 7T/28T #29 wire
- BN73-202 binocular core with 2T/8T. Where two stacked to get 1" length or
can you buy these cores in that length?

Except for the binocular core, it seems you are supposed to keep the primary
and secondary as far apart as possible while using a single layer of wire
for each.

What's the consensus on what is the best way of getting a 16:1 transformer?
Or, do all these methods work? I have some Mini-Circuits 16:1 transformers.
Don't know if they are fine or not for this type of application. I know they
don't work near high power broadcast transmitters. But, here at home I don't
have that problem and I am only single op here.

Also, how much will a common mode choke help with these type receiving
antennas? Should I use some type of balun or choke right before the matching
transformer?  Found 3 methods:
- 12" open air choke of coax. This doesn't seem too practical.
- 100 beads of FB73 beads on the RG6
- FT150-F with 7T of RG-174. 4T one way and 3T the other way.

Tnx for any feedback.
Tony
N2TK