I hadn't directly addressed dynamic range, but a receiver that is overly sensitive can get desensitize easier and dynamic range could be negatively affected which really screws up everything. Another reason high sensitivity is not necessarily a good thing. You don't usually see that listed as a receiver spec. It is definitely a radar spec. I suppose the point is that, a receiver can be more sensitive than another, but does it overall perform better than another that is less sensitive. It may not and the extra sensitivity may work well for one tuned signal, but not so well on another. There are many factors to consider. You should not necessarily consider a receiver that has a specification of 0.25 uV to perform better than one that has a sensitivity of 1 uV. It may or may not. And what is the signal-to_noise ratio? Since it is more sensitive, that receiver will require better image rejection and selectivity to perform well. Also consider that any received noise will be amplified at the same gain as the tuned signal at the RF front end, which is why external amplifiers at the antenna jack of the receiver can really mess up performance. RF amplifiers should be used as close to the antenna as possible to overcome feed line losses. They are good for that. They are not good for improving receiver performance.
External amplifiers commonly sold as pre-amps or antenna amplifiers are the problem when connected at the receiver. Connection directly at the receiver should be avoided. There are well designed very low noise amplifiers that may improve receiver performance placed before the RF front-end amplifier to improve the noise figure, but you would need to put that on the test bench to determine the resulting performance unless that amplifier was already designed to mate with that receiver. Such amplifiers usually cost well more than any of the scanners, even the SDS scanners.
Not just military. Military does not have an exclusivity on technology. What you just said is contradictory. Antenna amplifiers are used to overcome feedline losses. Assume your feedline loss is 10db. With a 10db low noise amplifier you can compensate for that if the amplifier is at the antenna. You can always use an amplifier at an antenna if you have a bias T or DC power injector. TV antenna amplifiers work this way and the amplifier is at the antenna and a power injector is at the end of the cable inside the house. But if your feedline has lost 10 db of signal to the receiver, it cannot recover what is not there as you just said at the receiver.
I have had 24 years in the military. Mil spec is more about interoperability, adaptibilty, survivability and extremely rugged. More than over spending. And the military uses plenty of COTS. COTS? Congress allocates the money. The military has to cope with the budget they are given and we have been very creative. Very creative! The military does not waste. Congress does. B52s in service since the last one rolled off the line in 1962 are expected to be in service until 2050. F15s are still the leading air superiority fighter bomber first entered service in 1976 and developed starting in the late 1960s. F15s are expected to be in service until 2035 and maybe beyond. Not to mention the KC135 airframe (Boeing 707) still in service and the C-130 which is probably one of the most rugged airframes ever. Congress canceled the F-22 contract for 750 and left it to 187 operational aircraft. Depending on who is controlling congress or in the Oval office it is either feast or famine. With a few years break in service I was in the military from 1978 to 2012 and most of those years were famine. Worst years were 1978 to 1981, 1992 to 2001, 2009 to 2012 for while I was in. Extrapolate the politics. BTW the F-35 is one of the worst projects ever approved by congress. The F-22 could be a replacement for the F-15. Keeping the F-15 and B52 in service has been a huge benefit to air superiority and tax payer savings. All the hype about Mig 25 and Mig 29s were just that. Russian propaganda. And the Mig 35 is being called the Dead Duck. And the Chinese copy of the F-22 does not have a marble size radar signature but instead as big as a Cessna!
