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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 21:53:29 +0100
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Subject: Re: LF: Re: HF SWR meters on MF?
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Status: O

Just  going  through  a  phase then ?

--------------------------------------------------
From: "Alan Melia" <alan.melia@btinternet.com>
Sent: Sunday, September 29, 2013 9:38 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: HF SWR meters on MF?

> No he is just emphasising his status as a boring ol' G3 pedant :-))
> alan
>
> ----- Original Message ----- 
> From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Sunday, September 29, 2013 7:57 PM
> Subject: Re: LF: Re: HF SWR meters on MF?
>
>
>> 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
>>>>>
>>>>
>>>>
>>>
>>
>
>