Hi Ash,
Some info:
- SWR curve median will always slowly rise.
No action; this has to do with parameters which slowly affect at higher
freq.
That is rather irrelevant on the lowbands 160-80-40
- Termination +matching adjustment is optimal at 'minimal amplitude' of the
SWR curve
Meaning; the waves must be 'as small as possible'.
It might never be flat, I have never ben able to get there. Maybe others can
give better advice here.
But does it matter when not SWR 1? No.
- Matching optimal beverage impedance to coax
Like when all is set optimal but the whole beverage antenna is not 450 Ohms
but 530 ==> stick with the 9:1
Or, at a BOG where installation is near ground, impedance is abt 220 Ohms
==> stick with 4:1
A better matching is possible by altering the transformer windings.
But again, does it matter?
Can you make more QSO's?
I have not seen/read any proof on this yet.
Please also note:
Local environment, as well as length/install- height of beverage wire will
determin the 3D pattern
Local ground/air humidity will change performance slightly
Adjusting F/B to local BC signal can be distracting because:
BC freq is out of band and a good F/B at <1600kHz does not mean it is now
optimal at 1830kHz as well..
Groundwave BC signals arrive at 0 degrees; you want to adjust FB at incoming
skywave (10< >50 degrees) signals instead
What reference you should use depends on your QTH and the first wave of
incoming (Europe?) QRM
I hope others, with more experience on this subject will have a better
answer here.
In general, my experience is a beverage antenna will work rather quickly and
perform well.
There is just no bad-adjustment possible.
73 Mark, PA5MW
-----Original Message-----
From: Topband <topband-bounces@contesting.com> On Behalf Of Ashraf Chaabane
Sent: Wednesday, July 04, 2018 4:40 PM
To: pa5mw@home.nl
Cc: topband@contesting.com
Subject: Re: Topband: Beverage Antenna Tuning
Mark,
I'm planning to have the termination value adjustment excercice for F/B
maximisation using a BC station signal. However, does SWR measurement have
to do also with the termination value? Or that's rather the matching
transformer that I should act on?
I now have an antenna analyzer and multimeter. What kind of optimization I
can carry out? (The beverage is permanently installed).
73 Ash
On Wed, Jul 4, 2018 at 3:23 PM <pa5mw@home.nl> wrote:
> Based on my field installed beverages experience, I would say this is
> exactly what I always read on my ant analyzer.
> Ground and local air/bush moisture level changes, like after rain or
> such, will affect readings too.
>
> I would do optimization only if this installation was permanent and
> you have the time and tools available.
>
> 73 Mark, PA5MW
>
>
>
> -----Original Message-----
> From: Topband <topband-bounces@contesting.com> On Behalf Of Ashraf
> Chaabane
> Sent: Wednesday, July 04, 2018 4:13 PM
> To: topband@contesting.com
> Subject: Topband: Beverage Antenna Tuning
>
> Hi All
>
> I measured the SWR in my beverage antenna; the SWR fluctuates between
> 1.5 and 3 in a range of 1.8 to 7 MHz. (See:
>
> https://drive.google.com/drive/folders/0B9AtNpPfAOUMRDNsaXROMG1VUTg?us
> p=shar
> ing
> )
> I know SWR should not vary too much. However, some people are
> suggesting adjusting the termination resistor. Others suggest checking
> the transformer number of windings for a good match. What shall I do?
>
> 73 Ash 3V8SS/KF5EYY
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
--
Ash ~ 3V8SS/KF5EYY
http://www.kf5eyy.info/
Phone/SMS/Whatsapp: (+216) 22670026
Skype: kf5eyy
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