[TenTec] PK232 and Paragon 585

[Vic Klein]

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

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To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Subject: Re: [TenTec] PK232 and Paragon 585
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec at contesting.com>
Date: Sun, 8 Jul 2012 06:47:52 -0500
List-post: <tentec at contesting.com">mailto:tentec at 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 at ptd.net>
To: <tentec at 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
>
>
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> -----------
> 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