I received mine today from Banggood, 30 days to receive it. I took it apart--the chip is the Gainsil GS 8091-TR. 350 MHz CMOS single supply op amp. Non inverting input is biassed at 1/2 Vcc and is capacitor-coupled to the input. The inverting input is tied to the output; the output is direct capacitor-coupled. There should have been a series resistor on the output to ensure stability, but there is none. You can find the data sheet for the IC on the internet.
I'm sorry, I'm wrong on the series resistor on the output; somehow tracing it out I missed the two parallel resistors that are in series on the output to the two parallel caps that then go to the output connector. The two parallel resistors measure 62.7 ohms, so I suppose each resistor is a standard value 120 ohms. So there is a series resistor on the output, and all is well.
Connecting this amp near the receiver as you show in this video would have the same effect as any internal preamplifier stage. However if you were to mount this at the base of your antenna you would probably see more benefit, as it would be amplifying the signal before losses as well as correcting the impedance mistatch between your antenna and your transmission lines.
I have one of these on order and it will be arriving within the next week. The plan is to use it with an adjustable tuned 'donut' antenna feeding an ATS-20+ where it's bound to increase selectivity dramatically due to providing around a 1MΩ load instead of around 50Ω thus significantly increasing the Q factor. Think back to crystal radio theory and it's easy to understand why this not only should but absolutely will happen.
One thing I have found (at least with my copy) of the RSPdx is that there is a certain amount of "bleed-over" between the antenna ports. They are not totally isolated. In other words if you disconnect all but one antenna and switch between ports, you will still receive a signal on the unconnected antenna ports. I wonder if the differences between the two antennas might be greater than what it appears due to the behavior of the RSPdx.
I would have liked to see you attach it to your Malahit radio hooked directly to the telescopic whip.antenna. That might be useful for a DX outings in the parks, field days etc. 73!
For Receiving only I highly recommend the Bonito MA305 with optional longer whip for more gain, good H155 Coax and ground it well and it's one fantastic antenna for it's size, great for DX and low noise, though as always this mostly depends on your location. The performance of the antenna is amazing for it's tiny size but do get the optional longer whip, good coax and ground it well before it enters the house. It only needs to be on a pole around 2-3 meters off the ground. It can be powered via USB power bank rather than noisy mains power supply. I'm able to power the bonito directly from my Malahit DSP 2, original Russian version. Minimises cable mess. The Bonito Megaloop FX is also another excellent antenna and probably a bit better for noisier environments. I have the 10 meter long version and use less amplifier gain, you can set this via jumper inside.
@@michaelnoardo3315 well to be honest there's people spending a lot more on DSP radios that sound really bad on SSB and they can't do ECSS either as a result of the DSP related distortion and low frequency cut off. So if someone got the Tecsun PL-680 and the Bonito MA305 they'd have paid much the same as with a much more expensive radio like the Tecsun PL-H501x or the New S-2200x which is a ridiculous price and they'd have a really fantastic SW DX setup. A radio is only as good as the antenna, no point paying so much for a radio and using a poorly performing and often noisy antenna.
It seems like your only ground connection is through the USB to the computer. A good ferrite choke on the USB cable and a good low noise ground should give better results I think.
The amplifier does seem to improve the ability to understand the transmissions - the noise increases but doesn't seem to increase as much as the transmission. For the price, it might be helpful under certain conditions.
It definitely helped with the SNR especially with the broadcast station where it went from 20 Db to 40 Db. It seemed to help with the SSB signals but those are harder to judge since there is no carrier and you need them to talk continuously in order to even get a SNR reading. Of course it's not going to work with a loop which are by nature low impedance and usually below 50 ohms
There are multiple types of loop antennas where one type is low impedance, one is high impedance and one can be tuned by the placement and size of the pick-up coil, etc.. For purely reception one can have tuned loop-antenna that's in practice parallel tuned circuit thus behaving almost like an open circuit..so that's the high impedance one..since it's tuned, one needs to tune the antenna at the same time as a receiver so some remote control and remote hi-Z amplifier is needed for outdoor antenna..however made well it's very good for weak signal work (antenna works also as a preselector helping the dynamic performance of the radio).. Then one can build 'shortcircuited loop' that responds in practice only to the magnetic portion of the electromagnetic wave; it has a directional pattern like from a teachers book and it won't pick up electrostatic noise.. Here the loop is typically built as low inductance as possible for a given loop area (eg. very thick pipe or 2 parallel loops) and the loop is connected to very low-Z amp of few ohms so it's only current that get's amplified..or more specifically the amp is transconductance amplifier..that antenna is not tuned and has wide bandwith like eg. e-field probes or antennas working with that principle.. I have all loop types and l.o.g-type loop on my yard so i can't really go and say that a loop antenna is a low or high impedance type of antenna since it's more like an umbrella term of antennas having loopy elements rather than single type of antenna.. Oh..and one can build cardioid pattern hf antenna with 180 degree switchable pattern (360 with 2 loops) by combining hi-Z vertical antenna with lo-Z shorted loop with a signal combiner (if eg. loop current would travel one polarity on one side, it of course travels other polarity on other side of loop.. vertical antenna current will match either side depending loop antenna connection polarity..and to the matching direction signal will double..to the non matching direction they are cancelling thus producin cardioid pattern..by flipping the loop connection polarity the cardiod pattern will go to mirror image..by having 2 loops with 90 degree angle one can have 4 direction electrically steered cardioid reception antenna system..)..that's very dx capable system and i have built one such antenna system as well..😅
Wise move asking the audience for their opinion on this subject 😅 Electrical I'm not going to even pretend I know what is going on. Audibly I can notice a slight improvement. Not to sure if its helping to boost certain frequencies of the sound coming out, but listening to the English it was slightly more clearer.
As has been said by a few others, "high impedance" would be a very electrically short antenna, substantially less than 1/10th of a wavelength. Think of a set-top telescopic whip, say a metre long, on the 75 or 49 m broadcast bands for example.
I use a couple of metres of wire into a 2N2222 buffer with T-bias. The low component count would suggest this device uses a similar design, unless that SOT23 is some type of amp chip.
I would try a LOG loop on the ground to see if you can change your S/N ratio. You might get a nicer signal, but honestly your noise doesn't seem horrible.
I'm in a high-noise environment (urban area) and have a hard time picking up ordinary 100W signals on HF, even CW. The last SST I participated in, I discovered I was only hearing 500W+ stations at all. I tried a passively-matched Loop-on-Ground RX antenna to try to reduce the noise floor as much as possible, but it's not enough. QRM removers also don't do much, as it's thousands of rf noise sources, not just one I can cancel via phasing. It's bad enough that I've lost interest in playing radio at home. I wonder if something like this with an even longer Loop-on-Ground (or perhaps Loop-near-Ground or non-loop longwire following the property line) would perform better for RX under these conditions.
What is the benefits of a Hi-Z antenna over a standard 50 ohm antenna? WHAT I had a lot of trouble with is receiving a low power 900 mhz signal I used 24 volt cellular phone base station receiver booster The frequency range was the higher 900 band or the lower 800 band, as the handheld output is 824 to 849 mhz But it did work for the 898 mhz range pretty well The biggest issue was the heat They got incredibly hot for just being a receiver pre-amp. They got hotter than a 100 watt transmitter on all the time. It would burn your fingers if you touched it. In the winter it was fine but the summer it was just too hot to use.
Have You tried this on long wave? Or the "beacon band" between lw and mw.. Your wire would be way too short there, thus very high impedance so in these frequencies that amp should do wonders.. also that high input impedance presents another quality that may present a problem of it's own at least dx-wise; It's very hard, almost impossible, to choke out the common mode type noise coming from the house (chokes can bring some few hundred ohm impdance which doesn't do much against specd 1Mohm input impedance..). So i would recommend at least putting the amp outside and farther from the house and trying to choke out the 50ohm feedline.. Basically following the same guidelines as with miniwhip.. Also on lower frequencies You shouldn't even need a wire..any shape metal object would work as a "capacitive probe" and surface area defines the voltage level received.. too large and you'd get distortion and im products on upper bands..too small and your reception is weak.. hard to judge by the looks of the guts, but i'd be weary of too large signals because of the im distortion.. I've been toying around with high impedance receive antennas and they can be very dx capable if implemented properly!
What is actual current draw? Looks as though device may run 3.7v direct as there didnt appear to be any DC -DC converter. This may indicate output power capability of amplifier. Even moderate levels signals on MW may cause overload.
You can't really apples to apples compare the setup between Antenna A and B as you have it setup. For starters running a long wire onto the 50ohm Antenna A input without some sort of matching is going to significantly reduce the performance of what the RSPdx is capable of. Secondly (not knowing exactly what the high Z amp does inside) It will probably help lower the noise floor on Antenna B if you give the high Z amp a short counterpoise wire on the ground side. A better comparison could be if you connect Antenna A via a Nooelec 9:1 UnUn Balun, which will level the playing field. Or even better is use a SDRPlay RSPDuo, which has a High Z input built in. In any way, love your vids thanks.
The other thing with the RSPdx is that the isolation between Antenna A and B is not great, so you have to disconnect one or the other for a real comparison. The RSPDuo solves this as it has two independent tuners.
The 50 ohm Sma Connector Impedance is Not seen as Any Impedance at the Long Wavelengths usage...The Input Sma Connector simply looks like a Moderate size Solder Blob signal Connection.....Works perfectly, No issues !!
Hi Matt, the issue here is that an 11m wire is not necessarily a high impedance above a few MHz. It is a 1/4 wave, close to the ground, on 40m. I would expect it to have much more effect on MF/LF than HF. Perhaps repeat with a shorter wire, say 2-3m? Also noted the no longer used QO!00 antenna in the garden.
I think you are mixing up radiation resistance and antenna impedance ... with an 11m wire you will have most frequencies above 7 MHz that qualify for a higher impedance, which is the reason the signal to noise improves significantly.
Excellent, Thanks for the info mate. Would be so simple to adapt it over to bias tee charging for that Cell Or even using a small solar panel To keep it topped up For use at the antenna end. Great Video Mate. 73 de VK3VKe
It's really a functional battery powered Lo noise Unity Gain Hi-Z (1 Mohm) Input to 50 ohm Out impedance Converter....The Slight S/N Improvement Demo in the Video is Typical 10 db Hi Z antenna to 50 ohm receiver Impedance Mismatch loss Correction gain....
I purchased a similar device on amazon, in addition to Hi Z it had some sort of airband amp for am. The device looks almost the same and cost 28 usd. Have you seen this... anyone? I havent had a chance to use mine yet.
For many decades now we have receive antenna jacks on radios and no one ever cared about the impedance. For a more repeatable test: Take any signal generator (Si5351 module is fine), attach a piece of wire of wire to the output and measure the SNR of the signal on both inputs.
The principle of maximum power transfer through matching the load, transission line and amplifier impedance is one of the foundations of RF engineering. It has been known for over a hundred years now.
Dear Matt, thanks for the test, interesting little box with surprisingly good results. You created a good test setup but then showed a not so ideal test ... when testing signal/noise don't do that with the strongest signals on the band, do it with the weakest, it will get you a better differentiation between the two. The 3 empty solder pads in the input and output section of the PCB seem to have been for an optional BAV99 dual switching diode, limiting every voltage peak exceeding 0.7V ... its sometimes good to have, keeps the amp protected, but at higher RF levels it can cause intermodulation ... so I wonder why they decided to leave it out? It seems to be ideal for portable operation to avoid any mismatches that will also cause you to pick up unnecessary computer/USB noise from a poorly terminated coax. For that price including the tiny lipo battery that is really a great deal.
I am at a complete loss to know why any manufacturer would use an SMA socket as a means of connecting a wire antenna to a device. I see that you had to resort to using an SMA to SMA male adaptor and an SMA PCB mounting socket in order to connect your wire antenna to the device. This must have added over £4.50 to the price of the device and entailed soldering, which a small number of people aren't equipped to do?
Try it with a massive undersize antenna and solid grounding on the shield. Ideally on something tower-ish out in the yard. It should ideally cover a very wide span without any tuning. For DIY projects: BUF802 looks interesting indeed, like should cover the full span of sdrplay in ONE* antenna! * Yeah right, could be interesting to see how it actually works! Probably forgetting something important.
It is a strange decision to use a standard 50 ohm SMA connector for a Hi-Z interface. Connecting antenna with high input impedance to 50 ohm connector creates an impedance mismatch. I would have expected just standard screw terminals for a ladder line which would be more suitable for a Hi-Z interface.
Most people will use it with a random wire or telescopic rod and no a very little co-ax, as such the 50 oh segment is insignificant, especially for receive.
I received mine today from Banggood, 30 days to receive it. I took it apart--the chip is the Gainsil GS 8091-TR. 350 MHz CMOS single supply op amp. Non inverting input is biassed at 1/2 Vcc and is capacitor-coupled to the input. The inverting input is tied to the output; the output is direct capacitor-coupled. There should have been a series resistor on the output to ensure stability, but there is none. You can find the data sheet for the IC on the internet.
I'm sorry, I'm wrong on the series resistor on the output; somehow tracing it out I missed the two parallel resistors that are in series on the output to the two parallel caps that then go to the output connector. The two parallel resistors measure 62.7 ohms, so I suppose each resistor is a standard value 120 ohms. So there is a series resistor on the output, and all is well.
Connecting this amp near the receiver as you show in this video would have the same effect as any internal preamplifier stage. However if you were to mount this at the base of your antenna you would probably see more benefit, as it would be amplifying the signal before losses as well as correcting the impedance mistatch between your antenna and your transmission lines.
I have one of these on order and it will be arriving within the next week. The plan is to use it with an adjustable tuned 'donut' antenna feeding an ATS-20+ where it's bound to increase selectivity dramatically due to providing around a 1MΩ load instead of around 50Ω thus significantly increasing the Q factor. Think back to crystal radio theory and it's easy to understand why this not only should but absolutely will happen.
One thing I have found (at least with my copy) of the RSPdx is that there is a certain amount of "bleed-over" between the antenna ports. They are not totally isolated. In other words if you disconnect all but one antenna and switch between ports, you will still receive a signal on the unconnected antenna ports. I wonder if the differences between the two antennas might be greater than what it appears due to the behavior of the RSPdx.
Yep, there is clearly a analog switch on the input, and they have finite isolation.
I would have liked to see you attach it to your Malahit radio hooked directly to the telescopic whip.antenna. That might be useful for a DX outings in the parks, field days etc.
73!
For Receiving only I highly recommend the Bonito MA305 with optional longer whip for more gain, good H155 Coax and ground it well and it's one fantastic antenna for it's size, great for DX and low noise, though as always this mostly depends on your location. The performance of the antenna is amazing for it's tiny size but do get the optional longer whip, good coax and ground it well before it enters the house. It only needs to be on a pole around 2-3 meters off the ground.
It can be powered via USB power bank rather than noisy mains power supply.
I'm able to power the bonito directly from my Malahit DSP 2, original Russian version. Minimises cable mess.
The Bonito Megaloop FX is also another excellent antenna and probably a bit better for noisier environments. I have the 10 meter long version and use less amplifier gain, you can set this via jumper inside.
Unfortunately the Bonito antennas are heavily overprized.
@@TheMicrofox I don't think the MA305 is over priced considering the performance vs size.
Im impressed how BONITO is powerful for RX , but it costs 240 Euros , too much
@@michaelnoardo3315 well to be honest there's people spending a lot more on DSP radios that sound really bad on SSB and they can't do ECSS either as a result of the DSP related distortion and low frequency cut off.
So if someone got the Tecsun PL-680 and the Bonito MA305 they'd have paid much the same as with a much more expensive radio like the Tecsun PL-H501x or the New S-2200x which is a ridiculous price and they'd have a really fantastic SW DX setup.
A radio is only as good as the antenna, no point paying so much for a radio and using a poorly performing and often noisy antenna.
It seems like your only ground connection is through the USB to the computer. A good ferrite choke on the USB cable and a good low noise ground should give better results I think.
Grounds don't help nearly as much as hams think.
The amplifier does seem to improve the ability to understand the transmissions - the noise increases but doesn't seem to increase as much as the transmission. For the price, it might be helpful under certain conditions.
Interesting device and video. Certainly raised signal level though perhaps the comparison was slightly skewed by the fact that the AGC was enabled.
It definitely helped with the SNR especially with the broadcast station where it went from 20 Db to 40 Db. It seemed to help with the SSB signals but those are harder to judge since there is no carrier and you need them to talk continuously in order to even get a SNR reading. Of course it's not going to work with a loop which are by nature low impedance and usually below 50 ohms
There are multiple types of loop antennas where one type is low impedance, one is high impedance and one can be tuned by the placement and size of the pick-up coil, etc.. For purely reception one can have tuned loop-antenna that's in practice parallel tuned circuit thus behaving almost like an open circuit..so that's the high impedance one..since it's tuned, one needs to tune the antenna at the same time as a receiver so some remote control and remote hi-Z amplifier is needed for outdoor antenna..however made well it's very good for weak signal work (antenna works also as a preselector helping the dynamic performance of the radio)..
Then one can build 'shortcircuited loop' that responds in practice only to the magnetic portion of the electromagnetic wave; it has a directional pattern like from a teachers book and it won't pick up electrostatic noise.. Here the loop is typically built as low inductance as possible for a given loop area (eg. very thick pipe or 2 parallel loops) and the loop is connected to very low-Z amp of few ohms so it's only current that get's amplified..or more specifically the amp is transconductance amplifier..that antenna is not tuned and has wide bandwith like eg. e-field probes or antennas working with that principle..
I have all loop types and l.o.g-type loop on my yard so i can't really go and say that a loop antenna is a low or high impedance type of antenna since it's more like an umbrella term of antennas having loopy elements rather than single type of antenna.. Oh..and one can build cardioid pattern hf antenna with 180 degree switchable pattern (360 with 2 loops) by combining hi-Z vertical antenna with lo-Z shorted loop with a signal combiner (if eg. loop current would travel one polarity on one side, it of course travels other polarity on other side of loop.. vertical antenna current will match either side depending loop antenna connection polarity..and to the matching direction signal will double..to the non matching direction they are cancelling thus producin cardioid pattern..by flipping the loop connection polarity the cardiod pattern will go to mirror image..by having 2 loops with 90 degree angle one can have 4 direction electrically steered cardioid reception antenna system..)..that's very dx capable system and i have built one such antenna system as well..😅
I would be interested how this would compare to an MLA-30 in terms of serving as an amp for a small loop antenna.
Wise move asking the audience for their opinion on this subject 😅
Electrical I'm not going to even pretend I know what is going on. Audibly I can notice a slight improvement. Not to sure if its helping to boost certain frequencies of the sound coming out, but listening to the English it was slightly more clearer.
Curious what the six pin chip was, since it appeared to be the only active device in the signal path.
Maybe a op amp with 9 or so dB gain?
As has been said by a few others, "high impedance" would be a very electrically short antenna, substantially less than 1/10th of a wavelength. Think of a set-top telescopic whip, say a metre long, on the 75 or 49 m broadcast bands for example.
I use a couple of metres of wire into a 2N2222 buffer with T-bias. The low component count would suggest this device uses a similar design, unless that SOT23 is some type of amp chip.
I would try a LOG loop on the ground to see if you can change your S/N ratio. You might get a nicer signal, but honestly your noise doesn't seem horrible.
I'm in a high-noise environment (urban area) and have a hard time picking up ordinary 100W signals on HF, even CW. The last SST I participated in, I discovered I was only hearing 500W+ stations at all. I tried a passively-matched Loop-on-Ground RX antenna to try to reduce the noise floor as much as possible, but it's not enough. QRM removers also don't do much, as it's thousands of rf noise sources, not just one I can cancel via phasing. It's bad enough that I've lost interest in playing radio at home.
I wonder if something like this with an even longer Loop-on-Ground (or perhaps Loop-near-Ground or non-loop longwire following the property line) would perform better for RX under these conditions.
I wonder how a 49:1 un-un would compare? It would have the advantage of being able to transmit through it too.
49:1 with 10m of wire would be way better as it would be resonant on a few bands from 20m up.
Randomly, aren't magnetic loop antennas high impedance? Would this help with a homebrew version of one?
An SDR doesn't need an amp as much as some sort of band pass filter to block the signals from out of band strong local stations.
What is the benefits of a Hi-Z antenna over a standard 50 ohm antenna?
WHAT I had a lot of trouble with is receiving a low power 900 mhz signal
I used 24 volt cellular phone base station receiver booster
The frequency range was the higher 900 band or the lower 800 band, as the handheld output is 824 to 849 mhz
But it did work for the 898 mhz range pretty well
The biggest issue was the heat
They got incredibly hot for just being a receiver pre-amp.
They got hotter than a 100 watt transmitter on all the time.
It would burn your fingers if you touched it.
In the winter it was fine but the summer it was just too hot to use.
Have You tried this on long wave? Or the "beacon band" between lw and mw.. Your wire would be way too short there, thus very high impedance so in these frequencies that amp should do wonders.. also that high input impedance presents another quality that may present a problem of it's own at least dx-wise; It's very hard, almost impossible, to choke out the common mode type noise coming from the house (chokes can bring some few hundred ohm impdance which doesn't do much against specd 1Mohm input impedance..). So i would recommend at least putting the amp outside and farther from the house and trying to choke out the 50ohm feedline.. Basically following the same guidelines as with miniwhip.. Also on lower frequencies You shouldn't even need a wire..any shape metal object would work as a "capacitive probe" and surface area defines the voltage level received.. too large and you'd get distortion and im products on upper bands..too small and your reception is weak.. hard to judge by the looks of the guts, but i'd be weary of too large signals because of the im distortion.. I've been toying around with high impedance receive antennas and they can be very dx capable if implemented properly!
nice and Very cheap but would this work on a discone antenna???
Makes a difference
What is actual current draw? Looks as though device may run 3.7v direct as there didnt appear to be any DC -DC converter. This may indicate output power capability of amplifier. Even moderate levels signals on MW may cause overload.
What is the ohm reading of the Hi-Z antenna?
You can't really apples to apples compare the setup between Antenna A and B as you have it setup. For starters running a long wire onto the 50ohm Antenna A input without some sort of matching is going to significantly reduce the performance of what the RSPdx is capable of. Secondly (not knowing exactly what the high Z amp does inside) It will probably help lower the noise floor on Antenna B if you give the high Z amp a short counterpoise wire on the ground side. A better comparison could be if you connect Antenna A via a Nooelec 9:1 UnUn Balun, which will level the playing field. Or even better is use a SDRPlay RSPDuo, which has a High Z input built in. In any way, love your vids thanks.
The other thing with the RSPdx is that the isolation between Antenna A and B is not great, so you have to disconnect one or the other for a real comparison. The RSPDuo solves this as it has two independent tuners.
The 50 ohm Sma Connector Impedance is Not seen as Any Impedance at the Long Wavelengths usage...The Input Sma Connector simply looks like a Moderate size Solder Blob signal Connection.....Works perfectly, No issues !!
Hi Matt, the issue here is that an 11m wire is not necessarily a high impedance above a few MHz. It is a 1/4 wave, close to the ground, on 40m. I would expect it to have much more effect on MF/LF than HF. Perhaps repeat with a shorter wire, say 2-3m? Also noted the no longer used QO!00 antenna in the garden.
I think you are mixing up radiation resistance and antenna impedance ... with an 11m wire you will have most frequencies above 7 MHz that qualify for a higher impedance, which is the reason the signal to noise improves significantly.
No, I do know what I am talking about. It would appear you do not.@@n1vca
I would want to test it at 500 Khz and below.
Excellent, Thanks for the info mate.
Would be so simple to adapt it over to bias tee charging for that Cell
Or even using a small solar panel
To keep it topped up
For use at the antenna end.
Great Video Mate.
73 de VK3VKe
How does this work with the youloop? since it is also a high impedence antenna.
Youloop is not hiz
It's really a functional battery powered Lo noise Unity Gain Hi-Z (1 Mohm) Input to 50 ohm Out impedance Converter....The Slight S/N Improvement Demo in the Video is Typical 10 db Hi Z antenna to 50 ohm receiver Impedance Mismatch loss Correction gain....
What Mini-Whip does
I purchased a similar device on amazon, in addition to Hi Z it had some sort of airband amp for am. The device looks almost the same and cost 28 usd. Have you seen this... anyone? I havent had a chance to use mine yet.
This should be good for sampling from transceivers that don't have SDR capabilities. I think also for dummy load signal sampling.
For many decades now we have receive antenna jacks on radios and no one ever cared about the impedance. For a more repeatable test: Take any signal generator (Si5351 module is fine), attach a piece of wire of wire to the output and measure the SNR of the signal on both inputs.
The principle of maximum power transfer through matching the load, transission line and amplifier impedance is one of the foundations of RF engineering. It has been known for over a hundred years now.
@@brownj2 All true, now quantify the effects on receive.
When looking on LW a lot of intermodulation artefacts are seen when the amplifier is active. This is not a good sign!
Dear Matt, thanks for the test, interesting little box with surprisingly good results.
You created a good test setup but then showed a not so ideal test ... when testing signal/noise don't do that with the strongest signals on the band, do it with the weakest, it will get you a better differentiation between the two.
The 3 empty solder pads in the input and output section of the PCB seem to have been for an optional BAV99 dual switching diode, limiting every voltage peak exceeding 0.7V ... its sometimes good to have, keeps the amp protected, but at higher RF levels it can cause intermodulation ... so I wonder why they decided to leave it out?
It seems to be ideal for portable operation to avoid any mismatches that will also cause you to pick up unnecessary computer/USB noise from a poorly terminated coax.
For that price including the tiny lipo battery that is really a great deal.
I am at a complete loss to know why any manufacturer would use an SMA socket as a means of connecting a wire antenna to a device. I see that you had to resort to using an SMA to SMA male adaptor and an SMA PCB mounting socket in order to connect your wire antenna to the device. This must have added over £4.50 to the price of the device and entailed soldering, which a small number of people aren't equipped to do?
Maybe it would be productive to run an S21 test on a VNA
Try it with a massive undersize antenna and solid grounding on the shield.
Ideally on something tower-ish out in the yard.
It should ideally cover a very wide span without any tuning.
For DIY projects: BUF802 looks interesting indeed, like should cover the full span of sdrplay in ONE* antenna!
* Yeah right, could be interesting to see how it actually works! Probably forgetting something important.
Is the voiceover read by an AI? There's something super uncanny about it.
No it’s my voice
the HI-Z input with an SMA is incorrect. I suspect this is a POS
Hi-Z telescopic antennas can have SMA connectors. Like the ones that come with the Malahit or DeepSDR etc.
It is a strange decision to use a standard 50 ohm SMA connector for a Hi-Z interface. Connecting antenna with high input impedance to 50 ohm connector creates an impedance mismatch. I would have expected just standard screw terminals for a ladder line which would be more suitable for a Hi-Z interface.
Most people will use it with a random wire or telescopic rod and no a very little co-ax, as such the 50 oh segment is insignificant, especially for receive.
Its worth a tenner, wouldn't give a score for it