I’m not understanding your (somewhat intense) reasoning here, or the manner of your strong reaction to those who are seeking to express their dissatisfaction with their situation. You asked for the published general specifications and you were provided them. Many purchasers took these specs as a stated SYSTEM specification; but, when they got their LimeSDR they found out that the RF front end design had a much smaller bandwidth. The confusion lies with the difference between the what the Lime Chipset is spec’d to do, verses what the LimeSDR can do. The chipset can indeed work over those ranges, but the LimeSDR system can only do so if it is properly matched to an RF input signal chain that can route it to the appropriate chipset RF inputs to get the right match. The basic RF amp and matching network design approach taken in this design does not support that well and requires changes to provide it. This will of course increase the cost/complexity and then you won’t be paying as little as you are for this platform. But, it seems reasonable to me that some (non engineer, but more user technical) folks feel a bit mislead since that distinction was not articulated (to my knowledge).
John
Sorry, but given the information out there they read more into it than it said.
Embarrassing perhaps, but factual and spot on.
They didn’t buy a platform, they bought a dev board that requires outboard to work.
That they didn’t understand that is evident again by your posts content as per your statement:
“Many purchasers took these specs as a stated SYSTEM specification; but, when they got their LimeSDR they found out that the RF front end design had a much smaller bandwidth. The confusion lies with the difference between the what the Lime Chipset is spec’d to do, verses what the LimeSDR can do…
… it seems reasonable to me that some (non engineer, but more user technical) folks feel a bit mislead since that distinction was not articulated (to my knowledge).)”
where you hit the nail on the head in that the purchasers mislead themselves as to what it was.
If they aren’t willing or able to do the footwork required to modify a bit of dev kit to their specs they should have known not to buy a bare circuit board in first release.
Those people got in over their heads on their own and should stick to packaged appliances that don’t need in house dev work to use.
It is as simple as that.
This again is not a commercial bit of finished polished product.
I’ve ordered 2 of the LNA4HF LNAs. Also, a HF->120MHz upconverter that has ~20dB LNA and LPF built-in. That arrives today. Gonna be an interesting weekend
ok, i bet you could set a SPF5043Z on the era-3sm+ pads and get 1.8db in better noise figure… but at HF that probably does not matter … unless your using a magloop or ferrite rod … and even then …
Good point about the mag loop as that is what I am using.
And thanks for the device pointer, I’ll have solder one in and see if it drops my noise floor.
Not a good idea. The SPF5043Z is not unconditionally stable on the HF frequencies and you may end up with the oscillator and mmic destruction at the end. You should not be concerned with the NF on the HF frequencies.
Well … i just spent 40min up and down the bands (switching in and out the SPF5043 LNA) … the bands seem dead around here at midnite …
WWV on 5Mhz and 10Mhz were real low this evening …
I could pick up some AM radio stations on 3.9444Mhz … mostly English and a few Chinese stations with deep fading …
The FPS5043 did make a difference … but not enuff to point to a deaf LimeSDR.
The PDF on the SPF5043 seems to be real close … about 12db gain @ 4Mhz …
It was the lower noise figure that stuck out at me. I could hear a difference in that …
My best settings for LimeSDR LNA was 4db and TIA maxed … the PGA didn’t matter too much as long as it was not minimum …
I think the LimeSDR needs to get a better noise figure AND more bit depth … 12bits are not too far from 8bit – like most all DVB Tv dongles … i could be wrong that a 16bit would be beneficial …
I hope that the manufactured noise figure matches what its spec’ at (or lower) not worse …
Im wondering of those that have done the EasyFix to the Rx1_W are expecting a large signal height on the display …
My LimeSDR is not deaf and is quite satisfactory … only the weakest of signals will be missed (compared to my UHFSDR – and Atlas350XL) … and its not because of the gain, but because of the noise figure.
Just for the reference this is Rx1_W with modification, last night on 20 cm ferrite loopstick adjustable from 1,5 to 8,5 MHz, no preamp but hope to try with LNA4HF during the next week =>
