[RTTY] Station upgrade

[Tyler Stewart]

What IF is the DSP filtering in?  Unless it's in the second, it's at a
severe disadvantage to a crystal filter in that stage.  I've yet to hear of
a ham radio that didn't benefit from crystal filters...either in the form of
a "roofing" filter, or more conventional IF filters.  There is a good reason
why TenTec touts their roofing filters in the $4k Orion even tho they have a
super-duper DSP system. 

The MP DSP is really just an audio DSP, so it's of very limited value.
Unless you have a full bank of filters and a roofing filter from INRAD, it's
not a fair comparison.  I'd put one of my fully filtered MPs up against any
other radio, except maybe an Orion on RX.

On filters, I prefer the INRAD 400hz filters for RTTY.  250hz tends to
degrade reception just a bit due to the group delay characteristics and
ringing and leaves no room for those who call off frequency.  500hz is what
everybody else has and not really optimal for 170-200 hz shift.  400hz is
just a bit narrower and still wide enough for CW contesting.

Ty K3MM


-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On
Behalf Of Bill Turner
Sent: Saturday, February 25, 2006 11:14 PM
To: AD5VJ Bob; rtty at contesting.com
Subject: Re: [RTTY] Station upgrade

On Saturday, February 25, 2006 8:03 PM [GMT+1=CET],
AD5VJ Bob <rtnmi at sbcglobal.net> wrote:

> I fellows relatively new mode for me.
>
> What do you guys consider the best brand/model radio for
> RTTY barring cost factor?
>
>  73 fer nw,
> Bob AD5VJ
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Of all the ones I've used, I like the IC-746PRO the best. It has a RTTY 
filter mode which provides a twin peak filter, 300 Hz bandwidth and 
amplitude limiting. It's DSP IF system is superb. Another good one is the 
Kenwood TS-870S, likewise with a superb DSP IF system, but without the other

bells and whistles. I also had a Mark V FT-1000MP Field which is acceptable,

but not in the same league as the two above.

I presently have an IC-756PRO III on order, which I bought mainly for the 
spectrum scope. It has essentially the same IF system as the '746PRO. If it 
proves to be as good, then it would be my top choice.

Bottom line: DSP IF filtering is a must. Crystal filters are history. Good 
crystal filters are expensive and DSP can do the same thing or better for 
pennies, relatively speaking.

73, Bill W6WRT

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