08-08-2017, 07:02 PM
Hi.
Well today I have spent some time with the SDR receiver. initially I thought all was well but on a deeper test I can say that they really don't cut the mustard on lower frequencies.
They perform well on high VHF and above, strong signals though are not tolerated very well with intermodulation and images being a very big problem.
Purely by chance a flight most likely overhead had radioed the tower on VHF and the splatter was seen on the Spectrum Analyser over some MHZ, listening to Shandwick met report was obliterated by this and other flights. Above around 350Mhz things improve and this is where these receivers score.
Band 2 Radio is heard between 43 and 50Mhz and also in the 10 and 11 meter band, backing off the RF gain helps but the receiver then gets deaf.
On low frequencies (100Khz- 30Mhz) on the spectrum analyser (SDR Sharp) there are spikes all over the place with no aerial attached, this could be spurious reception from pick up off the PC but using two different PC's the problem remains, in fact the problem is less than using my older RTL dongle that has a plastic case and directly plugs into a USB socket.
AM on Medium wave is very noisy, no signal produces a lot of hash and even feeding from the loop on the local there is still noticeable noise, to its credit though the noise blanker works well enough but needs a fair amount of adjustment to get it right. Listening to a distant station 9Khz from my local actually works OK with the bandwidth reduced, again though there are many images right across the band and this is repeated right down to 100Khz.
Ideally these receivers need better filtering, the addition of an ATU would be useful but another issue is the delay between adjusting the ATU and hearing and seeing the result, around 3-5 seconds of delay is frustrating.
For the money they are reasonable but any serious listening is really difficult. I was able to resolve some amateur activity on 20 meters but the noise level is too high for anything but the strongest signals.
I have used a Perseus before and it is a fantastic receiver.
So don't waste your money on these receivers unless you are using it for High VHF and above. Below that use a proper radio.
Well today I have spent some time with the SDR receiver. initially I thought all was well but on a deeper test I can say that they really don't cut the mustard on lower frequencies.
They perform well on high VHF and above, strong signals though are not tolerated very well with intermodulation and images being a very big problem.
Purely by chance a flight most likely overhead had radioed the tower on VHF and the splatter was seen on the Spectrum Analyser over some MHZ, listening to Shandwick met report was obliterated by this and other flights. Above around 350Mhz things improve and this is where these receivers score.
Band 2 Radio is heard between 43 and 50Mhz and also in the 10 and 11 meter band, backing off the RF gain helps but the receiver then gets deaf.
On low frequencies (100Khz- 30Mhz) on the spectrum analyser (SDR Sharp) there are spikes all over the place with no aerial attached, this could be spurious reception from pick up off the PC but using two different PC's the problem remains, in fact the problem is less than using my older RTL dongle that has a plastic case and directly plugs into a USB socket.
AM on Medium wave is very noisy, no signal produces a lot of hash and even feeding from the loop on the local there is still noticeable noise, to its credit though the noise blanker works well enough but needs a fair amount of adjustment to get it right. Listening to a distant station 9Khz from my local actually works OK with the bandwidth reduced, again though there are many images right across the band and this is repeated right down to 100Khz.
Ideally these receivers need better filtering, the addition of an ATU would be useful but another issue is the delay between adjusting the ATU and hearing and seeing the result, around 3-5 seconds of delay is frustrating.
For the money they are reasonable but any serious listening is really difficult. I was able to resolve some amateur activity on 20 meters but the noise level is too high for anything but the strongest signals.
I have used a Perseus before and it is a fantastic receiver.
So don't waste your money on these receivers unless you are using it for High VHF and above. Below that use a proper radio.
