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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <524864BC.60908@iup.uni-heidelberg.de> <6C620201432A459BBD435B0ADFA16DD3@gnat> <524870EB.3090708@iup.uni-heidelberg.de> <A383CCBFF0BD4A278A91483A1A1C4AF5@AGB>
Date: Sun, 29 Sep 2013 21:38:18 +0100
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Subject: Re: LF: Re: HF SWR meters on MF?
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Status: O

No he is just emphasising his status as a boring ol' G3 pedant :-))
alan

----- Original Message -----=20
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 Sch=E4fer" <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),=20
>> resonate it to the TX frequency by using a variometer. Then use a ferr=
ite=20
>> transformer to match the impedance to 50 Ohm.
>>
>> Insert the SWR meter (i'm using this one for HF:=20
>> http://www.astrosurf.com/luxorion/Radio/swr-meter.jpg   (you can find =
the=20
>> 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=20
>> (i.e. add a significant reactive component to the feed point impedance=
)=20
>> so that the resonance is lost. I bet that the reflected power will ris=
e=20
>> dramatically. Then i interprete that the SWR meter tells me that i hav=
e=20
>> lost the resonance, since the ratio of the transformer didn't change.=20
>> Sure, there could be a change of the earth losses which cause a change=
 of=20
>> the resistive component of the impedance. This will result in a change=
 of=20
>> the SWR as well. But these changes are small compared to the possible=20
>> 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 Sch=E4fer"=20
>>> <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=20
>>>> 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=20
>>>> oscilloscope...)...
>>>>
>>>>
>>>> 73, Stefan/DK7FC
>>>>
>>>
>>>
>>
>=20