[TenTec] PK232 and Paragon 585

[Vic Klein]

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 at contesting.com>
Subject: 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec at contesting.com>
Date: Sat, 7 Jul 2012 21:55:35 -0500
List-post: <tentec at contesting.com">mailto:tentec at 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 at msn.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Cc: <wd9hdq at 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 at arrl.net
>
> Thanks.
>
> Tim, WD9HDQ
> _________________