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From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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Date: Sun, 29 Sep 2013 19:57:06 +0100
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Subject: Re: LF: Re: HF SWR meters on MF?
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Status: O

Ha  Alan is  making a technical  point  ... : 0,)

--------------------------------------------------
From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
Sent: Sunday, September 29, 2013 7:26 PM
To: <rsgb_lf_group@blacksheep.org>
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" 
>> <Stefan.Schaefer@iup.uni-heidelberg.de>
>> To: <rsgb_lf_group@blacksheep.org>
>> 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
>>>
>>
>>
>