[RTTY] External DSP devices

[Robert Chudek]

Jacob,

An external audio DSP unit will help fight some interference, but it is not the right answer to your problem. I have the Timewave DSP unit, but it is a disappointment for serious RTTY contesting.

What you really need is a radio that provides selectable filters of 500 Hz or tighter. If you're hearing RTTY stations 2.5 KHz away, these signals are desensing your receiver by applying excessive AGC. It's the "FM principle". The loudest station captures the radio and you (your decoder) can't hear the weaker stations.

One radio that is relatively inexpensive that works well on RTTY is the Kenwood TS-450SAT. Also, the TS-690SAT is the same radio but includes 6 meter coverage. You can install optional 500 Hz (or 400 or 270 or 250 Hz) filters in either transceiver. The filters work on both CW and RTTY. In addition, the radio has true FSK built in, so you eliminate the AFSK issues. The current product in this line is the TS-570.

I might sound like a Kenwood salesman, but I know this radio because I have a TS-690SAT and have used it on RTTY. I have not used the TS-570.

These transceivers come up on eBay from time to time and seem to sell for $400 ~ $600 depending upon the condition and options. As a matter of fact, there's a TS-690SAT on eBay right now, Item 5860705398 as well as a couple of 450's.

There are probably other lower cost radios that provide good RTTY capabilities too. But this is the one I can tell you about first hand.

My opinion is save your money on the external DSP unit and put it toward a second rig (or an upgraded rig)!

73 de Bob - K0RC


* * * * * * * * * * * * *
Message: 7
Date: Sun, 29 Jan 2006 19:57:39 -0500
From: "K8JWT" <k8jwt at adelphia.net>
Subject: [RTTY] External DSP devices
To: <RTTY at contesting.com>
Message-ID: <000301c62538$2b492cd0$6800a8c0 at K8JWT>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original

I am looking into buying a external DSP device for contesting as my Yaesu 
FT-840 is crappy on SSB/RTTY as I can hear stations as far as 2.5KC away 
from me.  Was looking at the MFJ-784B I think it is as it is $200.00 cheaper 
than the TIMEWAVE DSP-599z.

So was wondering if anyone has used or is using one of these devices, the 
MFJ that is...

Jacob Tennant - K8JWT