Radio Performance

Here we take a look at how the R20 performs as a radio. Yes, it does have a whole bundle of features, but how does it measure up in pure radio performance terms?

To cut a long story short, the sensitivity below 1GHz is generally very good. There is one exception to this which may cause military airband listeners some difficulty. At 300MHz, the R20 changes over between two band stages. At the very upper extreme of the band stage which takes us up to 300MHz, my R20 becomes very deaf. This only affects a 10MHz slice but it may be a real problem to some people who have need to listen to traffic between 290 and 300MHz.

The following chart was drawn from a quick test on my signal generator (HP 8656)

I don't have a sinad meter so figures given here are at the point where the squelch opens and a weak but smooth and readable tone is heard in all cases.

The above chart shows just how much voltage is required at the antenna socket in order to produce an acceptable signal. As you can see, at just below 300MHz, it needs a whole 9µV in order so give a good signal. This is 45 times the normal voltage required. 

So that brings to light an interesting finding. As the IC-R20 gets above 290MHz, sensitivity begins to fall off sharply. At just below 300MHz, the sensitivity is very poor but as soon as you go past 300MHz, the next band stage kicks in and all is well again. This shows a bit of a problem in this area but it is confined to a small part of the band and I'm happy to report that the rest of this 200-400MHz region appears very healthy.

It's worth bearing in mind that this test was carried out on just one radio, my own, and it may be just down to poor alignment on my particular radio. I made these tests as a result of comments on the IC-R20 group that the radio appeared to some users to be deaf on the military airband.