Ha Alan is making a technical point ... : 0,)
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From: "Stefan Schäfer" <[email protected]>
Sent: Sunday, September 29, 2013 7:26 PM
To: <[email protected]>
Subject: Re: LF: Re: HF SWR meters on MF?
Does it not?
I suggest to do a test: Use a MF antenna (on 160m, for this test),
resonate it to the TX frequency by using a variometer. Then use a ferrite
transformer to match the impedance to 50 Ohm.
Insert the SWR meter (i'm using this one for HF:
http://www.astrosurf.com/luxorion/Radio/swr-meter.jpg (you can find the
words "SWR" and "meter" on the instrument) into the signal path.
I bet it will show something close to 1:1. The detune the variometer (i.e.
add a significant reactive component to the feed point impedance) so that
the resonance is lost. I bet that the reflected power will rise
dramatically. Then i interprete that the SWR meter tells me that i have
lost the resonance, since the ratio of the transformer didn't change.
Sure, there could be a change of the earth losses which cause a change of
the resistive component of the impedance. This will result in a change of
the SWR as well. But these changes are small compared to the possible
change of the reactive part, especially on MF and LF...
73, Stefan
Am 29.09.2013 20:02, schrieb Alan Melia:
er ......an SWR "meter" will tell you nothing about resonance :-))
Alan
G3NYK
----- Original Message ----- From: "Stefan Schäfer"
<[email protected]>
To: <[email protected]>
Sent: Sunday, September 29, 2013 6:34 PM
Subject: LF: HF SWR meters on MF?
Hi MF,
Did someone try to use a normal HF SWR meter on 630m? They are
specificated down to 1800 kHz of course but what about 472 kHz?
At least it would be good to get some indication that:
-There is some output power (e.g. when using an IC706)
-One is coming closer to resonance
-Impedance is/comes close to 50 Ohm
I'm supporting a new potential MF RX station with limited equipment (no
oscilloscope...)...
73, Stefan/DK7FC
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