I called an old friend of mine who used to run the local Ham chapter. He was wondering why I would want to use an SDR for what I want to do. He suggested that if I am going to spend that much money why not buy a really good Shortwave base radio which has far superior selectively and sensitivity than an SDR. He said they even make software for the pc to control the radio. He suggested a nice Drake 8 I think that is what he said. He thinks SDR's take a lot of the fun and mystery out of SWLing. He said even the best SDR is no better that a mid priced Base unit which can be bought used for around $500-700. Does that sound about right to you? Makes me think of changing things up a bit. THANKS
Your friend is simply wrong. However, he is not alone, a lot of people feel that way about SDRs.
Once you get up into about the $450 and above price SDRs they compete with very good traditional receivers. The FDM S2 can hear everything my NRD-535 can on the same antennas, and the filters are more adjustable on the SDR, so that I can often hear things on the SDR that I cannot on the NRD. And the FDM S2 is about the bottom end SDR I run regularly. My Perseus, WinRadio G31DDC, G33DDC, and NetSDR compete with the best receivers I have ever owned, and I have owned pretty much all the top brands and models.
And testing bears that out, looking at the numbers resulting from third party tests, like the Sherwood Engineering Receiver tests, show that in every important factor, dynamic range, ultimate close and far signal blocking, phase noise, etc, the better SDRs are up there with and above the best receivers you can get.
In the ham radio realm radios like the Elecraft K3, Yaesu FTdx-5000, etc, are SDRs with a front panel (the core technology is SDR). And these radios are top shelf. But better yet (based on performance) are things like the Flex 6700 series, which are SDRs without a front panel.
Many SDRs have exceptionally good dynamic range. For example the Drake R-8 you mentioned has a narrow spaced dynamic range of about 71 dB, while the Perseus SDR has about 99 dB. That means that comparing the Drake to the Persus under the same conditions the Perseus can handle a close signal (close in frequency to the one you are trying to hear) that is well over 500 times stronger without adverse affect on the signal you are trying to listen to.
However once you do exceed the DR of the SDR the ADC starts to clip, much like overloading on a traditional receiver. But when the ADC clips every received signal in the range suffers. So SDRs are less graceful once their performance limits are met. You may have to use the attenuator a bit more, depending on your specific situation.
Now, SDRs are not for everyone. You are tied to a computer. And 15 years down the road, after 3 or 4 OS changes, will you be able to run the software for the specific SDR you might have? I can still fire up my Hallicrafters SP-600 or Collins R-390 and they are well over 50 years old, 50 years from now (probably half that time) I am certain my SDRs will not still be usable. Cables, OS's, data interfaces, something, will no longer be supported.
So maybe SDR does not fit you, that is fine, but don't dismiss them on performance. Cheep, low end, SDRs are low performance, of course, but compare apples to apples. If you are talking a $500+ used traditional receiver (probably over $1000 new) make sure to compare it to an SDR in a similar price range.
T!
PS, you might be able to tell I have drunk the SDR koolaid. I basically converted from traditional radios to SDR 7 or 8 years ago, including o the ham side, using a Flex-5000A as my primary transciever. If it is any indication, I still have all my traditional radios, I almost never get rid of a radio, and I almost never use the traditional rigs. Typically the traditional radios set on one or two freqs for specific stations or services, while the SDRs do the grunt work of digging out new and hard to hear signals.
