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Review of New SOTABeams 2m-FM Bandpass Filter

The specs say in band attenuation is less than 3 dB and 25 dB plus at 155 MHz. In VK the troubles are at 160 MHz and above.

I’ve built band pass filters for 2 m with low loss but they are relatively broad. I have one that is about 150 kHz wide and less than 1 dB loss. At + 600 kHz it’s about 40 dB down. It weighs 20 kg.

73
Ron
VK3AFW

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I found ‘Cyrn-Y-Brain’ to be my biggest nightmare with 5/9 of interference coming from the comms mast. Used the SOTAbeams filter and it sorted the issue straight away :blush: no interference what so ever! It was good to get in your logs this past week.

73, GW4BML. Ben

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Yes, it was good to make the contact from The Wrekin, and from Walton Hill the previous week.

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Good to see that they perform as advertised. They took a lot of effort and many iterations to get them right.

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Hi Richard. I wonder if your ears were burning on Tuesday when I was up Cyrn y Brain (GW/NW-043) and praising your 2m filter yet again. Not only is it very efficient in knocking our interference from those horrible masts it is also so compact and portable that it lives in a rucksack pocket all the time and so is around when needed. The only real problems is that it is (presumably!) ineffective in dealing with the same problem on 70cm!! Making contacts on 2m (with the filter) was a doddle but on 70cm fm I was getting S5 noise across most of 433.425 to 500 (I didn’t bother to try any higher). I had noticed in the last couple of years that interference on 70cm was increasing but now it has got much worse - even on summits with no masts and no obvious industrial areas nearby (GW/MW-044 Moel Famau S2 70cm intereference on Wednesday from where?). I do realise that my VX-7R has a reputation as a ‘barn door’ but others are having the problem as well. How about this as a new retirement challenge,…please! It seems that more and more activators are giving 70cm a try (or are avid users like myself) so there is a steadily growing market out there…

Thanks very much for reading my comments - despite my wilful ignorance on Thursday when I didn’t recognise your callsign when activating Gyrn Moelfre (GW/NW-049). As you gathered, things had not gone well - and later got far worse when we drove to Rhialgwm (GW/NW-046) and had no chance of getting up the footpath owing to the extensive windblow. We then had to abort our attempt via the bridlepath to the east (Llwybr Heulen) owing to fences and the approach of dusk with a long drive home - enhanced by the road into Welshpool being apparently closed. Had I realised who I was talking to you would have heard my praise for your little 2m filter first hand. Hearty apologies again.
73 Viki

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