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 <[email protected]> On Behalf Of Ashraf Chaabane Sent: Wednesday, July 04, 2018 4:40 PM To: [email protected] Cc: [email protected] 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 <[email protected]> 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 <[email protected]> On Behalf Of Ashraf > Chaabane > Sent: Wednesday, July 04, 2018 4:13 PM > To: [email protected] > 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 _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
