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FT-847 vs. FT-817 on 123 MHz RX


I'd like some further opinions please if anyone has any.

Back when the FT-817 came out, I bought one for the main purpose of using it
as a microwave IF rig - particularly for AO-40.  This is what I am using for
receive on AO-40 today.  I do this because I've not wanted to experience
transmitting into my AIDC downconverter on accident.

W9AE, told me about his transmit inhibit modification for the 847 and
yesterday I performed that.  I wanted to be able to do computer controlled
tuning, etc.  The mod was simple to do and works great.  However, my results
with the 847 are less than encouraging when listening to the bird.

My IF from the downconverter is at 123 MHz.  With my FT-817, I hear the
beacon at levels of S7 to S8.  The "noise" in the system is at S0.  I've not
yet calibrated my S-meter so I can't say how much dynamic range that is, but
it's probably at least 16 to 20 dB.

On the FT-847, it's a different story.  The noise by itself (on sat or off
sat) is around S3.  The best I could get the beacon was S6 or S7.  Turning
off the internal preamp, drops the noise down, but then the beacon is about
S3 or S4.  Not a very good dynamic range.  The difference in copyability of
QSOs is tremendous.  Guys that I could easily copy on the FT-817 are not so
easy on the FT-847.

I am wondering if the FT-847's front end starts to roll off at 123 MHz.  The
FT-817 is a wider band radio and you can listen to FM broadcast, etc. with
it.  So I am betting it has a more wide open front end.  I am wondering if
anyone has seen similar results.  My assumption is that at 145 MHz, the
FT-847 plays much, much better.  Anyone care to confirm this?

Now I wish I'd not done the mod!  I could have been playing on the bird and
working the 5N0 instead.  I'm back to using the two separate rigs.



Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."

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