Friday, September 16, 2011

Measuring Sensitivity Of Some Cool Receivers

I've been fortunate enough to have a large variety of receivers coming (and going) at my Kongsfjord QTH. Some are/were mine, some were here on a temporary basis. Two of the latter category are the Icom IC-7800 transceiver, and the Icom R-9000 receiver. Both very high end, both in terms of performance and price. Lots of thanks go to Olav Skår, LA9VFA, who let me play with these superb radios.

Of course I never resist the temptation to measure the sensitivity of a receiver. The IC-7800 is stated (as all Icom receivers and transceivers are) to have reduced sensitivity below 1.8 MHz. As far as I know, all their radios produced in recent years are not desenstized on MW. This was confirmed for the IC-7800 as I measured a uniform -106 dBm to -108 dBm (around 1 uV) throughout most of its frequency range (600 to 20,000 kHz).

The R-9000 however is an older model, and it was indeed rather deaf on MW with figures around -92 dBm or 4 uV. On SW, it was marginally less sensitive than the IC-7800.

I finally got round to measure my new netSDR from RF Space too. A uniform -101 dBm or 2 uV was measured from 600 to 20,000 kHz. I had hoped to see it a few dB better, but it equals the SDR-IQ, a bit better than the QS1R and marginally weaker than the Perseus and the Winradio Excalibur (G31DDC). An external preamp would help.

Parameters: Measured with a signal generator while running AM mode with 6 kHz bandwidth, AGC off, and using 30 % modulation of a 400 Hz tone.

Update: OJ wanted pictures of the wonders, so here they are:


Tim Bucknall said...

Thanks for the testing, will you be able to keep the 9000 for the dx season?
i'm fascinated by that rx, it would be great to see how it performed at a top class dx site like kongsfjord
and if its deafness is hugely noticeable in real world situations

is the audio wonderful?

i nearly bought a 9000 in 2007 when i was upgrading my shack but i'd had a lot of problems with second hand radio equipment and i'd read about an overheating problem so i bought a R-9500

but i still find the 9000 mysterious and exciting ;-)

Bjarne Mjelde said...

No, I won't keep it for the DX season. The largest conventional receiver I will use is my trusty not-so-old 746Pro which is second only to my R-390A when it comes to sensitivity. It's all about SDRs nowadays.