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Call Sign : 26-CT-231 Posts : 14 Times Thanked : 0 Join date : 2019-08-11 QTH or Location : Cambridge Equipment Used : Linoln 2
Subject: Home base A99 HIGH SWR Mon May 10, 2021 5:01 pm
Trust you are well.. help please Antron A99, took my old (20 years) antenna down over the week end, put my new? A99 (well brought it in 2011 but not used store under the stairs) SWR threw the roof so high.. adjusted the rings.. no joy, I have check my coax all fine.. SWR meter ok.. check continuity between the sections all good... so not sure what's up.. time to buy a new A99..
On setting up my antenna could I isolate the antenna from the mounting pole, attach a earthing feed straight to the aerial using a jubilee clip, may lose some back ground noise level or is still the best way to attach straight to the mounting pole.. as normal.. earth from that...
Posts : 12 Times Thanked : 1 Join date : 2020-04-20 QTH or Location : W Yorks Equipment Used : Grant II, Antron 99
Subject: Re: Home base A99 HIGH SWR Wed May 12, 2021 11:16 pm
Hi Andy, it sounds like your A99 might be terminally ill - with the rings locked together somewhere central-ish you should be able to find good swr somewhere between 26 and 28 megs.
The isolated mounting and/or earthing thingy would only be a minor manipulation not intended to correct high SWR, but well worth playing with once you get the basics in place
For my own Antron, I have isolated from the mast and I use a Line Isolator on the coax around 8.5 foot from the feedpoint. Works for me right now, though I have had good results without isolation too. If I wasn't isolating the mast I would just ground that rather than the antenna directly, but as I am isolating I am grounding neither. It's hard with all the up/down of the antenna but if you can you try as many variations as you can you should find the magic combo that seems best for your own setup...
Call Sign : M0GVZ / 26CT1760 Posts : 420 Times Thanked : 31 Join date : 2019-11-13 QTH or Location : IO94SA Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike Age : 51
Subject: Re: Home base A99 HIGH SWR Thu May 13, 2021 4:31 am
Did you replace the coax? 20 year old coax will be well shot even if it meters out OK. I bet if you were to strip back some of the outer insulation from the plug end you'd find green or black braid from water ingress. Usually a problem like that won't show itself until it's disturbed.
Call Sign : 26-CT-3971 / M7TDV Posts : 306 Times Thanked : 17 Join date : 2021-01-30 QTH or Location : Cirencester, Gloucestershire Equipment Used : SS6900N, Xiegu G90, DX-300 for SWL, all antennas home-made
Subject: Re: Home base A99 HIGH SWR Thu May 13, 2021 8:34 am
I've come across a couple of posts on the net in recent past where people have said their bottom section has been faulty out of the box. If yours is by chance it's obviously too late to send back now, but you could open it up and take a gander.. see if there is bad solder joint or something else weird going on in there. There's at least one web page if you do a search where someone has stripped one of these down, so you know what to expect inside.
Personally if buying a replacement I'd go for plain 1/2 or 5/8 silver rod. A lot cheaper and more girth = wider bandwidth.. most of the A99's radiating element is just a wire inside. I know there's other factors to consider like strength in winds etc, but that would be my choice.