I am not down on the Duo – it is what it is and it does a number of things that I cannot do with other radios. My real issue is the process used by the QST Product Review Lab for measuring IMD DR rang

#elad

Dear all, I'm really happy to read this discussion thread as it confirms what I've been thinking for some time now : it's more and more difficult to differentiate the equipment in the Radio-Ham market

#elad

One more point to ponder. The IC-705 does not have dither. Yet it’s DR value is about the same as the IC-7300 that has dither. And Rob’s measurement of DR on the 705 compares with favorably with QST’s

#elad

I agree that enabling dithering on a radio (if it has that option) improves the DR. I see no logic from QST as to how they figure that using a 3rd signal with the Duo is the same as turning on ditheri

#elad

All i know is what I was told, it was tested in stand alone mode, software was never used. We all know that the radio is far better than many of the radios above it on the list. Yet he still puts it s

#elad

Sherwood's process is fine, it is just that it doesn't give a useful result for radios with a non-dithered ADC. His numbers are entirely accurate so long as you don't connect the radio to an antenna o

#elad

Hi Paul, It might be, but how so ? could you explain ? 73's, Alain F4HFS Le 13/01/2021 à 20:18, Paul Jones a écrit :

#elad

It what way is his testing flawed? Rob tests all of the receivers with the same process – two signal generators. I use the same test process and almost identical test equipment and I get the same resu

#elad

Sherwoods testing of the duo is flawed

#elad

On the IC-7300, enabling IP+ turns on dither and does improve the DR (less than 10 db improvement). Here is a graph that shows the difference in DR with dither on and dither off. DR at MDS – Dither Of

#elad

Hi Klaus, I was wrong on the QST Review. I got my numbers mixed up. Looks like the value was 99 db at 14 MHz for a 2 Khz spacing. 73 Clint W7KEC

#elad

<quote W7KEC> It is my understand that the QST Product reviews use a 3rd signal to simulate noise. They measured a DR of about 70 for the Duo in their 2016 review. <unquote> Clint, Where in that QST r

#elad

Some like the NPR tests and some do not. The NPR test equipment is very hard to find – most of it is 30 to 40 years old. However, a complete set of equipment can be purchased for about $300. On Adam F

#elad

For Rob’s receiver tests, he turns on Dither is the radio supports that option. The IC-7300, the Perseus, and other models support dither. However, there are radios that have a very high DR without di

#elad

I had the belief (from tech articles) that NPR measurements are the way to go for -at least - SDRs. Analog and SDR transceivers and receivers behave different re. 'old school' tests. That's also been

#elad

If the two source signals are pure tones, then you'll get pretty terrible results as there is no dither signal injected into a DUO as far as I know. A proper test of a radio with a straightforward ADC

#elad

Single / two tones tests on a wideband SDR are meaningless as they tell you nothing about the quality of the A/D process. The proper way to test such a receiver is with broadband notched noise, or a c

#elad

I am not sure. I don’t have the ability to inject a signal from a 3rd signal generator. A couple of things to keep in mind. Putting a HF pre-selector on the front end of the Duo should improve the DR,

#elad

Hi Clint, does injecting a realistic level of wideband noise (or some additional non-harmonically-related signals to provide dithering) change the results at all? Neil G4DBN

#elad

I just ran the same tests several times on my Duo. The results came out the same each time. The challenge in testing the Dynamic Range of SDR receivers is that the DR bounces all over the board, depen

#elad