[TenTec] Pegasus - digital

Tue Nov 25 12:44:52 EST 2003

Mark and John,

I caution you and others to not take the audio isolation too lightly.  The
importance is not to the audio level, the importance is keeping one piece of
equipment from damaging another.  While it is rare, an electrical "spike"
from one unit can damage the other unit.  By isolating the audio between
systems, you significantly reduce the chance of the computer damaging the
radio or the radio damaging the computer.  I personally know of an instance
where this happened and have heard from other hams on the Internet of it
happening to them.  Not a high risk, but a risk none the less.

I also had a ground loop like you Mark with the Jupiter, but using the
interface eliminated the problem (I had everything grounded).

Also, unlike Buck, Donner http://home.att.net/~n8st/ seems to have a higher
customer satisfaction rating on eBay and Donner's interfaces are a bit less
expensive.

Duffy 

-------Original Message-------

From: tentec at contesting.com
Date: Tuesday, November 25, 2003 12:21:35 PM
To: tentec at contesting.com
Subject: Re: [TenTec] Pegasus - digital

John,

If you want to get started simply (receive only), you can just run a
suitable cable from the Pegasus line out jack to the soundcard line input.
You probabaly won't need any isolation and the level should be easy to
adjust using the soundcard mixer input.

I'll think you'll find that the Pegasus works well for the soundcard modes.
There are a couple of little gotchas, though.

1) Make sure that the Pegasus and computer are grounded together. I run a
cable from the Pegasus ground lug to one of the screws on the computer case.
Before doing that, I tried a lot of different isolation methods and couldn't
eliminate a DC ground loop no matter what I tried. With the ground in
place, the ground loop went away (this seems somewhat backwards to me, but
it works).

2) The audio input on the Accessory jack is at the same level as the mic
input. It's not really a line in level. You will need some sort of padding
to reduces the level if you take the computer soundard line out.

3) The audio output on the Accessory jack is higher than a line level output
and higher than the line output on the Pegasus front panel. As mentioned
above, you can run a cable from the Pegasus line output directly into the
soundcard line input and should be able to adjust the level using the sound
card mixer program. However, if you use the audio output from the Accessory
jack, you'll probably find that you have the sound card input levels set
near minimum and still have too much level. If you go the Accessory jack
route, you'll probably need to pad the input level.

4) Check out www.buxcomm.com. Buck makes the Rascal series of sound card
interfaces, both pre-assembled and as kits. I made a few mods to the Rascal
interface that make it more usable for me.

a) The interface is designed and built to use one of the serial control
lines (DTR) to control PTT. Most software is configurable to use either DTR
or RTS (the other possibility). However, I've come across an occasional
program that was not. So I wired in a SPDT center off switch that allows me
to select which line (DTR or RTS) is used. The center off position also
provides a way to disable the interface or as an emergency shut off if the
computer hangs.

b) The transmit audio has a trim pot to adjust the level. I replaced that
pot with a larger one and mounted it so it could be adjusted from the
outside of the interface

c) The receive audio doesn't have a level adjustment, but I added a pot that
could also be adjusted from outside the interface. I find both of these
ajdustment pots easier to use than messing with the soundcard mixers.

5) when adjusting the transmit audio level on the Pegasus, run the RF output
at max (100w). Adjust the transmit audio level (using the interface pot or
the soundcard mixer) until the Pegasus' ALC light just comes on then back it
off so that the light is completely out. You don't want any ALC action or it
will distort your PSK signal. I've found that that's usually about 50
watts, which is more than I want to run, so I usually back the audio level
off even more. Even with 20 watts, the Pegasus heat sink can get warm if
you are long winded, so you may want to provide a fan to blow air across the
heat sink.

6) When you use an interface that requires (as most of them do) a serial
port to provide PTT control, that will have to be a separate one from the
one used by the software that controls the Pegasus. Some of the newer
software, such as MixW, can control PTT by sending a DDE command to the
radio control program. However, none of the Pegasus control programs that
I've seen respond to these commands.

7) Look into MixW. It's a single shareware program (about $50) that does
almost all the soundcard modes, including PSK31, MFSK16, Hell, SSTV, RTTY
and CW. It also has support for contesting and general logging.

73 and Good Luck,
Mark, N8ME

----- Original Message -----
From: "John Hunt" <ve3jwh at sympatico.ca>
To: <tentec at contesting.com>
Sent: Tuesday, November 25, 2003 11:37 AM
Subject: [TenTec] Pegasus - digital

> Hi to all,
>
>
> Just got the Pegasus and want to set up for digital,
>
> I understand there is more than one way, would be looking for the best
access of this mode to run with more than one version of software.
> Thanks for any insite from those who have run this rig in its many
factions
>
>
> 73 de John
> VE3JWH
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>

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