[ICOM] Icom 706MKIIG vs Yaesu FT450 vs Venerable old FT-757GX

Gerry Pement ve7bgp at shaw.ca
Sat May 17 14:28:59 EDT 2008


Hello John and others.

I just had experience with the FT-450 for a few minutes when I was over 
helping a friend set up his new FT-450 for PSK and RTTY. The FT-450 
seemed really quiet compared to the IC-706MKIIG. I have had 8 years 
experience with my IC-706MKIIG rig. That rigs is an example of a 
Receiver that has too much Sensitivity. It is noisy and has poor Signal 
Handling when you use it on a Beam or Loop Skywire antenna even if you 
keep the preamp off. I leave the Preamp off on all my HF radios that 
have Preamps on them they lead to a noisy Receiver and poor IMD 
characteristics. The Preamps are designed to make up for poor antennas 
like the inefficient antennas when you go mobile on HF or are in a 
Covenant Deed restricted District were you need to use "Stealth 
Antennas".  I have a Venerable old Yaesu FT-757GX sitting next to my 
IC-706G and I find my 24 year old FT-757GX blows the doors off the MKIIG 
for a quiet Receiver and the Full QSK on the Icom is a Joke compared to 
the smooth QSK the FT-757GX has. You use both with Preamp Off and Fast 
AGC. The FT-757 has whisper quiet QSK and the QSK on the IC-706MKIIG 
sounds like Grand Central Station with its relay's noise. The FT-757GX 
is a pleasure to use on CW contesting in the ARRL DX Contest several 
times I heard myself as part of the Pile-up and what a  great surprise 
the DX station came back to me from the pileup. FT-757GX's Shift and 
Width does a great job digging the desired station out of the Dog Pile! 
The FT-757GX came standard with a Narrow CW Filter the IC-706G the CW 
filter was a costly $200.00 option to add. I hope that give more 
substance th thid dual I made a Trio. I use the FT-757GX the most of all 
my radios including a pair of IC-751A's in my shack.
73
Gerry VE7BGP

John Geiger wrote:

But that will lead to a noisy receiver.  That kind of
sensitivity isn't useful on the HF bands, where the
atmospheric noise floor is above that, and so is the
man made noise floor.  Most sensitive doesn't always
mean better.  Selectivity plays a big part in receiver
performance, as does the front end and blocking and
IMD dynamic range.  The amount of noise one hears is
also dependent on how many IMD products the receiver
is generating in a crowded band.  

I think QST measured the 706MKIIG noise floor with the
preamp off around -138DBm, which really isn't useful
in real life conditions because the typical noise
floor most of us have when an antenna is connected is
around -120DBm or so.  The rest of the sensitivity
just comes thru as noise.

73s John AA5JG



  

The following are the specification for both radios
for a "10db S/N" ratio:
      IC-706		FT-450
HF	.15 microvolts	.2 microvolts
6M	.12			.16
VHF	.11			------

This would lead one to believe the 706 has a better
receiver.
End of subject. Its time we moved on to more
fruitful discusson.

   * 73's Jim W5IFP *





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