[RFI] Clamp on RF meter
doc at kd4e.com
doc at kd4e.com
Wed Feb 2 11:00:11 PST 2011
Would this device tell me anything a MFJ-259b or MFJ-269 or other
antenna analyzer would not?
WOuld the antenna analyzer give better overall context to the data?
> On 2/2/2011 10:26 AM, Michael Germino wrote:
>> I only used it if I have a problem. I used it to see where the
>> best placement of the ferrite was. Sometimes where you think the
>> placement is best, isn't.
> Not necessarily. Every wire (or conductor) is an antenna, whether we
> like it or not. A good ferrite choke acts like an open circuit,
> whereas a poor one (not enough turns) acts like an inductor, and one
> with too many turns can look capacitive. A choke simply ADDS its
> impedance in series with the existing antenna. If it's an optimum
> choke (near its resonance and a high impedance), it acts like an
> insulator to stop current AT THAT POIINT, but if the wire is long
> enough, the choke might turn the remaining wire into a half wave and
> increase the current in that part of the wire. Ditto with the choke
> that is L or C -- it simply shifts the current maxima and minima
> along that particular antenna.
> Bottom line -- measuring (or sensing) current in these conductors is
> certainly a worthwhile thing, but it's easy to mis-interpret the
> results if you don't view what you see in the light of the
> fundamental concepts of antennas.
> 73, Jim K9YC
Thanks! & 73, KD4E
David Colburn http://kd4e.com
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