I ask myself a few questions in order to optimize my reception, so if the specialists can give me some answers, here are my questions :
I have the opportunity to put the antenna higher 1.5 meters (5 Ft) surroundings, is it worth it ? Will I know the difference ?
Equally I know that the amp should be normally closer to the antenna, but given the length of the cable and its quality, it is worth it to mount a waterproof case on the mast of the antenna for to install the filter in, and thus to have it just after the antenna ?
If I do it I will have to connect the connections between the filter and the cable of the antenna, these connections will not deteriorate / weaken the radio signal ?
On this subject the adapter of 6 cm (0.20 Ft) between the antenna cable of 15 meters (50 Ft) and the filter, makes me lose in quality of reception, or that is negligible?
depending on yoourlocaal suroundings and your los farther away whats your distance that u get and max
wich is lowest.
higher always better esp with celphone kind of signals everything can block it
regards wynand
Depends on the houses surrounding your house.
If you can already see the horizon from the current antenna position, then it’s not worth it.
If the horizon is obscured by houses that are closer than let’s say 300 m, then i’d say it will get you a little bit of improvement. The closer the obstacles obscuring the horizon, the more increasing the height helps.
The antenna mounting position on the mast is not optimal though, it needs to be mounted at the very top of the mast. The bottom of the antenna (excluding the metal parts) is somewhat important to reception and the mast is blocking a bit of reception.
Don’t know if it really makes any difference, the overlap isn’t too long and i don’t have any reference how big the influence is.
50 ft of LMR400 is around 2.5 dB attenuation at 1090 MHz.
Getting the LNA up there would be an improvement, but as you already get really good range, i’m not sure if it would actually improve anything.
The attenuation before the signal is amplified is the critical part. The signal path after the LNA isn’t as important as the signal is already amplified, which is the critical step.
Depends on the quality of the adapter, a quality rigid one might be slightly better.
Which connectors are on the LMR400?
On adapters negable on qaulity one or 2 ok but not daisy chain conections trying to do different coax and adapters one coax 2 conections no problems , it start if u take different coaxes and different and a multiple of conections to start a heavy loss , loss would be maybe 0.2 db or something per conector depending on type.
mostly u work out loss with the coax and conectors included per foot or per meter.
3db is half of your signal loss and amps aways first before your coax top antenna and must be the best low noise amp needed
Wiedehopf I had the same thought for the bottom of the antenna that was hidden from the mast !
So having to go up to correct this I asked myself the questions mentioned above !
I think I’m going to add an extra mast of the same size as the current one at the same time, because I have some trees between 200 and 300 meters that are higher than my current position.
For your question about the connectors on the LMR400 it’s : N Male to SMA Male Jumper Cable, like you can see on the amazon’s webpage (link)
Can’t you connect that directly to the LNA?
Or is the the LMR400 N connectors on both ends and you are using a short jumper N to SMA?
If you want to improve that part, just get a rigid adapter instead of a jumper cable.
For a few trees that far away i wouldn’t bother with 1m extra height.
But having the base of the antenna 10 cm higher than the top of the chimney is probably a good idea.
Anyway the reception is very good already, the Airspy Mini will probably improve it.
I can connect the LMR400 directly on the LNA !
I have use this litlle cable only to relieve the connectivity of the LNA, because the cable in LMR400 is very rigid, and I was afraid that he forces too much on the connection of the LNA.
I will remove it ;+)
Well that’s very unfortunate. Immediately posted that when the cable is that rigid, you should rather just let it hang from the cable.
Curious that the signal is still good though.
My experience of the Uputronics amplifiers is not great. The build quality is fine but it’s things like this, cheap connectors and susceptibility to interference. Having used three of them in different situations, I prefer the RTL-SDR-LNA now even though it needs bias-tee to power it.
That sounds about right. Ceramic filter (more expensive) is better than SAW filter (cheap). More expensive, and perhaps better than both, is a cavity filter.
All my experiences are with the ceramic version.
Put 5W of 144MHz within 20m of a feeder equipped with the Uputronics LNA and it totally wipes it out, received signals drop to zero. I’ve seen this on two separate installations.
That may require a narrower cavity filter.
I have a ulari APRS (start [Ultimate Linux Amateur Radio Interface]) unit that puts out 7W. The antenna is within 1/2 a metre of the ADS-B antennas. I haven’t notices any drops but it is hard for me to check. I need to watch the transmit LED whilst watching the dump1090 screens. APRS is just a quick second burst though.
