Just a follow-up on this subject, Bob. I wired the new SignaLink USB to
the
audio in/out jacks of my Paragon, tested it for receiving and transmitting
PSK, and listened via the rig monitor to my audio. It sounded fine whether
the sound module was plugged in or not, so off I went to play with some
digital modes. This morning, coming up as an NCS on ECARS I had the linear
fired up and Whoa! Lots of RF into my audio. I removed the SignaLink cable
(that device was powered off) and proceeded without further issue, but I
decided to construct a 20dB pad as you suggested. After rummaging through
the junk box, I had the resistors and a small metal 35mm can that already
had an RCA socket on it, so I thought I'd just make an external pad to go
between the SignaLink cable and the Paragon...nothing would need to be
opened up.
Before firing up the soldering iron I decided to confirm the RFI could be
heard on the monitor, so I returned to 40m and fired up the linear and
gave
a test transmission. Nothing. No RFI heard at all. Hmmm...checking
everything, the only difference from the morning was that the SignaLink
was
powered on as I had been monitoring some 30m PSK. I switched it off, gave
another test transmission and WOW! There was the massive RFI back in the
audio. Several repeats show that as long as the SignaLink is powered on,
though, it does not seem to cause any issues. So, for now I'll leave
everything alone and test further, but you might mention to your buddy
with
the Omni VI to try leaving the SignaLink on and see what happens.
Meanwhile,
the external pad is sitting ready should I need to wire it up.
=Vic=
WA4THR
----------------------------------------------------------------------------
-------------------
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] PK232 and Paragon 585
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 8 Jul 2012 06:47:52 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Depending on what modes you intend to operate and what software you are
using, I have had great success simply using good quality shielded cables
between the computer soundcard and the radio. For modes, I've used CW,
AFSK, & PSK-31. In each case audio from the computer was used and the
radio was operated in USB mode with the VOX handling the RX/TX
requirements.
In order to address the issue of RF getting into the audio, I built a 20
dB
resistive pad and physically placed it at the connector for the Audio In.
This then required the soundcard to deliver a much higher audio level thus
improving the S/N on the cable between the computer and the radio. No
transformers were used and no level controls used. The control offered by
the software and the Windows Mixer environment was found to be most
adequate.
Audio from the radio to the computer was fed to the Line Input on the
computer soundcard. Here again one must be careful if their system does
not
have a Line In signal port but only has a MIC input. The radio fixed
audio
output will likely overdrive the input and problems abound. Attenuation
of
some 20 to 30 dB has been found satisfactory. A suitable attenuator is
made
in the form of a "T" network with the two series arms being some 10K ohms
and the center shunt being 680 ohms.
For PTT function, the VOX in the radio is adequately fast when correctly
adjusted for minimum hold time or delay, with VOX gain such the radio keys
reliably.
If one wishes to run PACKET or AMTOR or other modes then clearly an
interface is required. But here again, the interface is generating and
receiving audio to and from the radio and thus careful attention to
correct
levels must be maintained.
I am aware of one application where the SignalLink USB is being used with
an
Omni VI. He has buzz on his SSB audio if the SignalLink cable is
connected
to the Audio In on the radio. This is most likely the issue of the audio
level being low with a good bit of gain existing at the radio. I've
suggested a 30 dB T attenuator and operate the SignalLink at a higher
level
but he prefers to just disconnect the Audio In cable when not being used.
73
Bob, K4TAX
----- Original Message -----
From: "Vic Klein" <vhklein@ptd.net>
To: <tentec@contesting.com>
Sent: Sunday, July 08, 2012 5:36 AM
Subject: Re: [TenTec] PK232 and Paragon 585
This is timely. When I first got my Paragon I connected the Kantronics
KAM
interface I was using to the Audio In/Out jacks and got RF in the audio
chain. This was easily remedied by just switching to FSK keying using the
Mark/Space and CW Key jacks and I have used it that way for years. Now
just
this week my KAM has died and refuses to talk to the computer through he
serial port anymore, so I am looking at options like the SignaLink USB
with
a bit of concern, remembering the RFI issues from before. Is this method
Bob
mentions in use by others running PK232 on a Paragon?
=Vic=
WA4THR
----------------------------------------------------------------------------
-----------
Re: [TenTec] PK232 and Paragon 585
from [Bob McGraw - K4TAX][Permanent Link][Original]
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject:
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 7 Jul 2012 21:55:35 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
One of the issues I've had for years with not only certain earlier models
from Tentec but with other companies as well. This is the use of the
microphone input for other than microphone usage. In many cases, this
was
the only way to get a digital or data signal into the transmit audio
chain.
The typical result can be overdrive of the 1st audio stage which is
before
the gain control circuit. Once this stage is over driven no amount of
reducing the audio gain will correct the issue. The 2nd issue is that
the
level required to operate the audio stages correctly requires the
external
source to be a very low level which is followed by quite high gain
amplification. The result as Gary points out is RF in the audio.
While the Paragon provides an Audio In connector, it is simply another
input
isolated by a 10K resistor and feeding direct to the microphone input.
This
is not a true line level input. Correctly there should be some 20 to 30
dB
of attenuation located between the Audio In and the actual audio stages.
I've found this to be of great benefit hence the driving device is
required
to produce higher output level, thus the signal on the cable between the
driving device and the input to the radio is greater, thus the S/N ratio
is
improved. Otherwise, one is much less likely to experience RF getting
into
the audio.
Today's radios that do provide a Line Input are more likely to have a
separate audio path structured at the correct level configuration. They
are
much better suited to handle external devices for digital and data
operations.
As to the Paragon, this can be fairly easily accomplished by added two
resistors along with using the original 10K resistor. The two added
resistors are 10K in series and 680 ohms to ground to form a T network.
This will then require the external driving device to deliver much higher
signal to the radio and greatly lessen the likelihood of RF issues.
I have a basic philosophy to all of this: If it is a microphone then
connect it to the microphone input. If it isn't a microphone then best
find
some other way to get the required signal into the radio.
73
Bob, K4TAX
----- Original Message -----
From: "GARY HUBER" <glhuber@msn.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Cc: <wd9hdq@arrl.net>
Sent: Saturday, July 07, 2012 1:57 PM
Subject: Re: [TenTec] PK232 and Paragon 585
As I recall, it was easy to get RF in the SSB audio if a device like the
PK232 was left plugged in. You may be able to avoid the problem with
audio
isolation transformers (or RIGblaster nomic) and clamp-on ferrite beads.
73 ES DX,
Gary -- AB9M
-----Original Message-----
From: Tim & Darlene Isom
Sent: Saturday, July 07, 2012 1:28 PM
To: Discussion of Ten-Tec Equipment
Subject: [TenTec] PK232 and Paragon 585
Anyone out there using the Audio in, Audio out, and PTT on the paragon's
rear
panel hooked to a PK232?
If so, having any issues during normal SSB operation with the audio in
plug
remaining plugged in?
Can reply to me directly at wd9hdq@arrl.net
Thanks.
Tim, WD9HDQ
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