To filter or not to filter..this is the question!

[@mrovi789]

What happens if you have like 6dbi antenna, you add the filter and an amplifier, hotspot-filter-amplifier-cable->antenna. I have cotx and use this kind of filter, thinking of compensating with an amplifier of 9db on receiving.

[@viocaia]

Is not so simple.First you need a bidirectional amplifier, I mean it's amplifyng only RX but let TX untouched..like Flarm amplifiers. I should go the other way..antena/filter/amplifier/miner..but again , in this scenario with a cheap amplifier you can't send beacons anymore..it's one way path..RX in our case..try a better gain antenna like 8dB to compensate for the filter and that's it.It is proven the eficiency in crowded areas, the SNR noise ratio signal is better

[@PhilneyeOfTheClient]

Hello. My setup is as follows: 8.5 Omni(soon to be changed to 9db directional panel) - acasom cavity filter - Acasom 17rx/6tx amp - 7m LMR400 RF coax cable - bias tee - 5db attenuator - bobcat miner. The goal is for me to keep my amplification but bring my noise floor down to where it used to be before the amp install. The cavity filter helped a little bit but I am not quite there yet. I was planning on replacing my 5 db attenuator with a 2db attenuator and adding a 1.5 insertion loss SAW filter to the miner side. I figured if I was going to have 5 db’s attenuation anyway, I could put a couple of those lost db’s to good use in order to filter my signal even more and bring my noise floor down lower. Is this a good plan? I would love other’s inputs on this.

[@viocaia]

The noise increase because the amplifier..it's the single active part in the chain..I should start with the best antenna possible, means high gain, next a cavity filter to keep the signal as high as possible, very good to have the amplifier near the antenna! the followers devices doesn't matter..the noise is already there!..The single way to have a better SNR is to have a better amplifier, like Acasom v2 0.6dB or something..

[@PhilneyeOfTheClient]

@@viocaia I see…so even though there is an additional saw filter on the receiving end (miner’s side) it would fail to dampen any more noise that the cavity (on the antenna) already filtered? I hope I am understanding correctly. Has this ever been tested? If not, I would be happy to test and give results!

[@viocaia]

@@PhilneyeOfTheClient There are different noise types, the self noise..like any radio/amplifier have..that's part of the Signal to Noise Ratio and it's a sum of all active parts noises. The other hand, I believe your talking about the radio interference noise..those radio signal unwanted to certain receiving band or frequencies..well, in our case the cavity filter is doing the best job in cleaning the spectrum for LoRa only..next is the Acasom amplifier which already has a filter inside , anu other will do nothing but attenuate the signal..so there is no need for a saw or any filter after the amplifier..

[@viocaia]

@@PhilneyeOfTheClient Exactly what I meant, you already have a double filtering from cavity and Acasom..any extra will do nothing but losses of signal

[@PhilneyeOfTheClient]

@@viocaia thanks for the advice! With that information, I am now testing with ONLY the Acasom filter installed to see if my noise wall goes lower then it ever has been. That way I know the filter is doing it’s job and tuned correctly. Perhaps there are more hotspots I can pick up my having the most minimal noise 🤞. I’ll post results.

[@kevinkomlos30]

Nice video Viorel👍

[@viocaia]

Thanks Kevin! Hope it helps!

[@pajopatak1244]

please can you check thankful blue finch im from mobile tower 20m whitness 0 last 15 days i want too put saw filter from ali express and i have antenna 5.8 dbi rak is that good

[@viocaia]

Try a filter..

[@iamkian]

My dad will print a case for your NanoVNA. He will contact you soon.

[@viocaia]

Thank you so much!

[@scdoc689]

Try filters from rfareas, they develope super solutions and not expensive.

[@viocaia]

I will..thanks!

[@TheKuzmann]

Im trying to find their web shop but cant find it. How did u manage to buy their filter? Thnx

[@viocaia]

@@TheKuzmann I'm DIY filters, I ordered plain saw filters from Mouser and connectors from Aliexpress or Amazon..you need some soldering skills to..