[RTTY] FW: DXP-38- keep it or sell it?

Gary E. Jones garyejones at cmaaccess.com
Tue Jul 27 06:10:33 PDT 2010

I have an observation, but not sure if it is relevant or not. 

I have done 4 or 5 DXpeditions which were heavily or primarily done to
activate RTTY from rare or semi-rare locations where RTTY was most rare. I
have done them with MMTTY and I have done them with different versions of
HAL hardware RTTY demodulators. I have done them with both capabilities side
by side. One conclusion that was very easy to make was that at least with
MMTTY versions 4 or 5 years ago, there was a huge difference / advantage of
the HAL 4200 and HAL DXP-38s and MMTTY and the RTTY hardware was far
superior in the applications I was using. Now, that is an application where
there are hundreds of people all calling me simultaneously spread over 5-8
KHz and the hardware has to try to quickly dig out one signal from the
hundreds and get it clearly decoded on the screen and in this situation, the
hardware solution dug out the signals far better than MMTTY. There was no
comparison between the two. The hardware with RTTY DSP built in could dig
out signals that were nothing but incomprehendable with MMTTY.

Now that said, things may have changed but the hardware was so much better
than the software / radio combination that I simply don’t use MMTTY anymore.

Now, the situation is very different from "this end or in contests. Even in
contest operation here stateside, or as the "caller" in a DXpedition pile
up, we rarely find ourselves hearing more than one or two stations calling
us simultaneously or in close proximity, and not hundreds. As a caller in a
DXpedition, we are generally hearing only one station (the DX station) plus
the cops and intentional QRMers. In that situation, we have the greater
power of todays modern transceivers and their sophisticated DSP capabilities
and some more time to fool with controls, and in this situation, maybe much
more common, there might be parity between the approaches. 

However, there was no parity at all between the two approaches "from the
other side"

The only other observations is that if you get a look at AA5AUs station, you
will see a pair of DXP-38s sitting on top of the rigs....

If you decide to sell your DXP-38s, I will buy one or both of them to go
with my own...    (PS, for 35 bucks, I purchased a EDGEPORT USB to 4 serial
port professional ITS type serial port emulator on ebay (you can buy 8 and
16 serial ports also) and it interfaces easily to any USB port only
computer. Piece of cake)


                   Gary        W5FI 

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On
Behalf Of Rudy Bakalov
Sent: Tuesday, July 27, 2010 4:45 AM
To: F.R. Ashley
Cc: rtty at contesting.com
Subject: Re: [RTTY] DXP-38- keep it or sell it?


You are bringing up a good point. Clover and other modes are certainly a
good reason to keep them...except that I am strictly a contester and won't
use them for anything but RTTY:-)
I brought the pair to K1TTT for this year's WPX and could not see any
advantage vs. MMTTY, although we didn't go through the trouble of feeding
them with the audio from the Timewave DSP-599zx. For me, it boils down to
performance- does it copy any better than MMTTY or not.

Rudy N2WQ
--- On Mon, 7/26/10, F.R. Ashley <gdadx2 at clearwire.net> wrote:

From: F.R. Ashley <gdadx2 at clearwire.net>
Subject: Re: [RTTY] DXP-38- keep it or sell it?
To: "Rudy Bakalov" <r_bakalov at yahoo.com>
Date: Monday, July 26, 2010, 9:51 PM

I vote to keep them.  I still have my DXP38 and use it quite often for
Clover and also Amtor and Pactor ARQ modes.   I guess it all boils down to
how much you use them vs. the cost of the USB to serial cable.   I have 2
computers, one is a newer laptop that does not have serial ports, so I run
the  DXP38 off the older computer.
I have not made an recent HAL vs.soundcard program comparisons, socannot
help you there.   I'd keep them just in case you get the bug to run ARQ
modes.. there are still some of us who do.   We usually get on Clover on
Sundays on 14065.50 LSB, the old "calling freq" for Clover.

73 Buddy WB4M

(now I know where to find one in case mine blows up, hi)

I have a pair of DXP-38 modems that I got a couple of years ago, but never
bothered integrating into my station. I no longer have a computer with
serial ports and was wondering if the DXP-38 was worth the USB to serial
cables. I know it's juts a few bucks, but sometimes less is more, i.e. keep
it simple.
So, compared to MMTTY, how well does the HAL play? My thinking was to use it
in diversity reception, fronted by a Timewave DSP-599zx in RTTY tone pair
regeneration mode or just the data mode filter. This is where the complexity
comes into play.
So, keep them pair or sell them? If keep them, shall I bother with the DSP
front-end or just feed them with the regular audio from my Icom 756P3s?
Thanks for sharing your thoughts.
Rudy N2WQ
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