RE: LF: remote antenna tuning

[Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>]

Hello Gary, Graham, Dave,

 

thanks for the info. I will build the MBMU tuning meter.

 

73, Rik  ON7YD - OR7T

 

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Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Gary - G4WGT [g4wgt@tiscali.co.uk]
Verzonden: vrijdag 8 november 2013 21:44
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: remote antenna tuning

Hi Rik,

Yes, I used the M0BMU LF Tuning meter for some while on LF & MF with excellent results. But now I use a Scopematch slightly modified to switch to the current sensor mode of the LF Tuning meter.

See this page & the following page :-

http://myweb.tiscali.co.uk/wgtaylor/LF%20&%20MF%20Experiments%2013.html

Click on the pictures to enlarge.

So with the Scopematch feature I can get the resonance, voltage & current phase spot on visually on my double beam 'scope or switch to measure the antenna current from which I can estimate my ERP.

The Scopematch is placed (in the shack) at the Tx output after the LPF, I have also placed it at the base of the antenna & found no major difference.

The antenna tuning is carried out with a remote motor controlled from the shack.

http://myweb.tiscali.co.uk/wgtaylor/LF%20&%20MF%20Experiments%208.html

73, Gary - G4WGT.


I

On 08/11/2013 19:44, Rik Strobbe wrote:

I had a look at the M0BMU LF tuning meter and will built it.

Does anyone used it on 475/500 kHz? Maybe the transformers need to be adapted but that should be no real problem.

 

73, Rik  ON7YD - OR7T

 

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Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan Schäfer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: vrijdag 8 november 2013 19:53
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: remote antenna tuning

Oh yes, or, a phase meter (M0BMU) and a battery operated variometer motor. Without an additional cable to the shack. Then the SWR meter in the shack confirms that everything is fine.

73, Stefan

Am 08.11.2013 19:40, schrieb pat:

Hi All,

A suggestion: battery operated tuning device at antenna end and "wireless" link back to shack. Wireless can operate at a non-interfering frequncy (HF/VHF/UHF/Optical).

73






On 08/11/13 16:09, Stefan Schäfer wrote:

Hi Rik,

Am 08.11.2013 16:06, schrieb Rik Strobbe:

Hi Stefan,

 

remote tuning of the loading should be done by optimizing SWR (at the TX), not for maximum RF current.

If one keeps that in mind there is no problem.

...which is in agreement with what i said.
But once you have matched your antenna to 50 Ohm on resonance and you can only vary the reactive part of the antennas impedance (after doing QSY), then you will get the maximum antenna current at best SWR (assuming that Rrad+Rloss is constant which is not to far from reality).

I am not sure if I will keep the remote variometer tuning. It needs some extra wires to the loading coil and I am not sure how long the small DC motor will function properly with all the rain and frost coming up.

Here it holds since more than 2 years for LF now..

73, Stefan

-- 
73 de pat g4gvw
es gd dx
qth nr Felixstowe
East Coast UK

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