[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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