[Antennas] Elementary Antenna Question

Tue Oct 6 19:52:59 EDT 2009

On 2009年10月03日 7:12 PM, Andy wrote:
>> Also, it isn't so much of a problem on 20m, but the MFJ-259 has a
>> wideband detector, so strong signals from local AMBC or other
>> transmitters can make for some pretty strange readings, although this
>> doesn't appear to the issue here. But on 160m and 80m, it is often a
>> real pain.
>>>> I'm not sure, but I thought the problem happened on all bands, because it
> has a wideband detector. That is, it's still receiving local AM broadcast
> signals even though the MFJ-259's local oscillator is oscillating on a 20m
> frequency.
>> If the 259's frequency control also changes some sort of bandpass or
> highpass circuit (which I thought the '259 didn't have) in addition to the
> oscillator, then this problem would go away when you use it on higher freq.
> bands.
>> Andy
>The MFJ does have a broadband detector, but the antennas being measured 
on the higher bands usually don't pick up as much signal from AM 
broadcast band transmitters, which are the most common culprits. If you 
live near WRNO, WCBQ, WWCR, WYFR, or other shortwave broadcaster, 
prepare for headaches with high band HF antenna measurements, too.
73, Terry N6RY