[CW] What about a FT-450 for CW?

scott mcmullen scottamcmullen at yahoo.com
Fri Nov 14 15:33:26 EST 2008


--- On Fri, 11/14/08, Michael Baker <k7ddmjb at qwest.net> wrote:

> I am now using a 1984 vintage TS-930S? I find the 930 somewhat 
> noisy but love the QSK. And when operating field-day then I seem 
> to be the only one not being QRM'ed by the others - they QRM each 
> other and I QRM them in some extent, but I come out on top usually:)

The attributes that cause the type of interference you 
experience at Field Day are either transmitted phase noise 
(owing to the transmitters), or poor blocking dynamic range 
and/or front end overload (owing to properties of the receivers), 
or some combination of both.

According to the ARRL, the FT-450 had BDR of 138 and 134 dB on 
80m and 20m (at 20 KHz spacing). 

The ARRL didn't measure BDR when they reviewed the TS-930S (in 
1984), but it was measured by Sherwood Engineering 
(http://www.sherweng.com/table.html), and was 143 dB (at 100 KHz 
spacing). I suspect this was for 20m, although the site doesn't
specify.

The measurements can't really be compared exactly, owing to the 
spacing difference at which they were made. 

Remember that for quantities specified in dB, every 3 dB of 
difference is a factor-of-two improvement, so your TS-930S
looks to me as if it could be substantially better (perhaps 
even by a factor of 8x?) than the FT-450. 

In fact, the TS-930S has better BDR than most new rigs, even quite
expensive and highly acclaimed ones. I would hang onto it if I were
you; even if just for Field Day! You could spend alot of money
and still not have better BDR!

For yourself and others at Field Day, consider building a set of
band pass filters to whittle away at the transmitted phase noise,
and help with front end overload. 

A couple of us in my Field Day group each built a set of the ones
described at:

http://www.arrl.org/tis/info/pdf/8809017.pdf

and our group has very few problems with intra-station interference,
(as long as we only put one operating position on a given band).

73
Scott
W5ESE





      


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