First I have to connect a wire from 10.1m long. Then there comes an inductor from 34uH
and then again a piece of wire from 1.85m. For 10 and 20m the inductor has high
impedance and will block these frequencies. For 40m the inductor makes the antenna
electrical 20m, a half wave length.
According the information from PA0EJH we can make the inductor from 91 turns on a
PVC pipe with 19mm diameter. The wire has a diameter from 1mm. I had only 16mm PVC
so I needed 124 turns for an inductance of 34uH. A larger diameter is also possible,
how bigger the diameter, the less turns are needed.
PVC 25mm round, 1mm wire, 64turns wounded tight, Length about 64mm
PVC 32mm round, 1mm wire, 44turns wounded tight, Length about 44mm
PVC 40mm round, 1mm wire, 334turns wounded tight, Length about 33mm
Of course itís recommended to measure the exact inductance of the coil. I use an LC-
meter designed b y the VERON Meppel and is available via PE1ACB.
I have a telescopic fiber mast form 15m long and setup the antenna vertical. First I had
to trim the 10.1m wire a little bit for an SWR at 20m near to 1. On 10m the SWR is 1.5.
Now check at 40m., there was the SWR 1.3. No trimming required, itís just fine so. Now
I could test with the transceiver. Great signals and much less noise than my half size
Itís an easy to build antenna with a high rendament and great performance. But if you
donít want to make the antenna you can buy one at Rob PA3EKE site
worth the money to by one.