Fw: Topband: Inverted L for TX
k8mn at earthlink.net
Sat Mar 29 16:41:46 EST 2003
Jerry T Dowell wrote:
> Your trouble may be that the MFJ259 usually will give erroneous readings on
> 160M because of BC station pickup on the antenna. That meter is not useable
> at my QTH on any 160M antenna. I have heard that there is a high-pass
> available from MFJ that can solve the problem.
Just to echo what Jerry writes, I had a terrible time getting a borrowed
'259 to give good 160m readings in Helsinki. Using my own meter in
Tanzania, I still observed 160m readings which were off by 30-40 KHz.
Here in rural West Virginia, the nearest MW broadcasters are 25 miles
away. The nearest high power broadcasters is closer to 40 miles away.
I still note errors in the readings off by 30 KHz on 160m and by 75 KHz
on 80m. Once I calculated by how much the readings were in error, it
was a simple matter to adjust the 160m coaxial inverted "L" and to tweak
the vacuum variable cap used in the 80m inverted "L".
MFJ's high pass filter is a good idea but it may not be the cure. A
high pass filter could easily be homebrewed and mounted in a minibox as
an alternative to purchasing the MFJ unit.
Dave Heil K8MN
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