Tested and recommended LNA's?


#1

Greetings,
I am looking for a replacement for this favorite LNA which has dried up:
“Wideband LNA with FM notch filter”

Does anyone have an LNA they have tested and like as well? I have one of the above units deployed but I need moar. Sure, I could buy and test several units but it seems like several folks have already done that here :-).

Also, I have two LNA4ALL’s but they have failed me. One I managed to mechanically break and after repairing it a second time it no longer seems to work right, just raises the noise floor without improving any signals. The second unit I have basically does the same thing so I’m not impressed so far.

Thanks.


#2

Hi,
I’m testing this: https://iz7boj.wordpress.com/2019/04/11/spf5189z-lna-measurements-on-vna/
On the VNA it shows good results, although I can’t measure the NF.
In these days I’m trying it on my station.
73’
Alfredo IZ7BOJ


#3

Alfredo: Any further opinion pro or con for the SPF5189z LNA? How susceptible does it appear to be to overload from FM and Aviation band signals?

All: I’m also interested in finding a current good source for LNAs, preferably that can be powered from the RTL-SDR phantom power output. FM notch filtering would be great but I can use an RTL-SDR FM band filter if I have to. I’m currently testing an omni ground station and running an AMSAT-NA FoxInABox (FIAB) in parallel. Eventually, I’d like to locate 1 or 2 Satnog systems and the FIAB at/near an antenna and feed them from a common antenna via a LNA and splitter network.

I can borrow from my portable hamsat station an AMSAT-NA preamp (100-500 MHz) or an older Advanced Receiver Research preamp; I don’t want to permanently use the AMSAT preamp for this role and the ARR unit is good for 2M downlinks but may be too narrow for NOAA APT signals.

73 Steve KS1G


#4

So, I ended up getting a couple of these brand new/old stock at an amazing price at hamvention:

They are commercially made so no surprise they work well. Only thing is they seem to need an FM broadcast notch filter as there’s some harmonics being picked up way up into the VHF band. I’m using it for a separate project not related to satnogs, but if I get another ground station running it will probably be using one of these guys.

I’m still interested in a replacement for the now defunct FM filter+LNA though if someone finds one. Thanks.


#5

We need to design one so it can live on in the open…


#6

Anyone in this forum or that we know willing to take this on?

(We can fully support this with dev runs, production runs, tests etc)


#7

I have been working on band pass filter ideas lately to try and make my own for stuff. So I could maybe take a try.

No idea if I can come up with something good though


#8

Filters: I recently ordered a 144MHz and 440MHz bandpass filteres from HobbyPCB. I was told that they have about a 1.4 dB insertion loss at 137 MHz (design freq is 146 MHz). I plan to try them as an alternative to an FM broadcast notch filter. They said they are aimed at filtering out FM broadcast and DVB TV signals, not really designed for blocking airband or pagers. They are rated to 20W, so I may also try them for portable 2-way use with the amateur satellites.