The AM Forum

I was quite amused to read in the January QST review of the Icom R9500 receiver that this $13,500 receiver's AM sync detection barely works, and the max bandwidth is 3.6 kHz!

What a sad joke... for that price you'd think the receiver could pick up AM properly.

Steve WD8DAS

That last paragraph under the AM section of the review was referring to 3.6 kHz bandwidth SSB reception.  Long sentences with reverse syntax get us all the time.  But you are right Steve, at that price you'd hope for a little better AM performance than it has, but as we have come to realize here on the AM Forum with all of the experienced receiver guys, there is no such thing as a receiver with no weak areas.

I  re-checked Bob Sherwood’s site recently for new information, and he has a dissertation on the new DSP receivers having poorly implemented AGC action so far.

www.sherweng.com/documents/Dayton2007w.ppt

So the new engineers have to learn some things yet about the behavior of radio circuitry and learn to use their own product and listen before shipping it out. 

And like everything else with computers inside these days, the owner is burdened with a lifetime of firmware updating; new firmware revisions out already for the -9500!

Yea, Just like these guys who put two signals into the Flex barn door and call it dynamic range. Notice how Sherwood has not posted numbers on Flex. I know he has tested them. He sent me some data and my numbers agree.

Having used the 9500, it has variable bandwidths. For AM you can vary from 9 kHz to 0 kHz (if you like).

Sync detector appears to work fine. I haven't read the QST review, so I'd be interested in why they claimed it didn't work.


Frank, I didn't know you had a Flex. When will we hear it on the air?

Steve my QSD is a copy of the Flex front end. The only thing different is fixed gain in the op amps. My LO is cleaner because it comes from a crystal. I did all my testing around 455 KHz.

Seems to me I remember Sherwood indicating several months ago that he held back putting the Flex numbers up on his web site because he had submitted the data/article to the publishers of Passport to World Band Radio and he was waiting until the book went out for distribution.