[TenTec] Omni-VI QSK with Alpha 87A

[Paul Christensen]

I really wish that information would disappear, but the Internet is 
forever...

Barry and other's -- Please be careful with this set-up. I was part of the 
original discussion back in 1998 together with Terry, W6RU.  The concept 
looks great on paper, but results in hot-switching on the trailing RF 
envelope with some Alpha amps.  I detected the problem when the Jennings 
RJ-1A failed in my Alpha 77Dx.

The *only* way to proceed using the "Y" adapter requires scope monitoring of 
the keyed envelope to ensure proper system timing.  For those folks who 
don't own an oscilloscope, it may be possible to monitor the keying 
sidebands with a panadapter as the hot-switching will show up as excessive 
keying bandwidth.

I've said it before and I'll repeat it again.  The best way to handle the 
switching from the early Ten Tec's into most non-Ten Tec QSK amps is to 
sample Ten Tec's "T" voltage and buffer it with an open-collector or MOSFET 
device.  If anyone needs assistance with this, let me know by private 
E-mail.

Paul, W9AC


----- Original Message ----- 
From: "Barry N1EU" <barry.n1eu at gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, December 06, 2011 10:05 AM
Subject: Re: [TenTec] Omni-VI QSK with Alpha 87A


> Oops, I think I found the info on the Alpha forum.  I will add it to
> the Ten-Tec Wiki.  If anybody has tried this with an Acom 2000A or
> Alpha 99, please drop me a line.
>
> 73, Barry N1EU
>
> -------------------------------
>
> Omni-VI, Omni-VI+ (maybe others):
>
> Make up a cable with a diode in series to connect the 87A "relay" line
> to a "Y" that plugs into the "TX OUT" and "TX EN" jacks on the
> Omni-VI. The "TX OUT" and "TX EN" are connected together by the "Y",
> the diode connects to the center conductor of the third leg of the
> "Y". The polarity of the diode has the cathode (band end) connected to
> the Y, diode anode goes to RELAY jack of Alpha. This will allow the
> TenTec "TX OUT" signal to key the amp when it enables the radio for
> transmit. This works on both CW QSK and SSB. DO NOT do this with any
> other amplifier unless you know that the keying line polarity of the
> amplifier is correct AND that the amp keying circuit is of very small
> current. This is only recommended for use with a Alpha 87A or 89 (they
> use PIN diodes for fast T/R switching). Thanks to Terry W6RU for this
> circuit (posted on the TenTec reflector).
>
> All other radio/amp combinations, use the amplifier keying relay in
> the radio to the RCA jack on back of amp labeled RELAY.
>
>
> On Tue, Dec 6, 2011 at 10:02 AM, Barry N1EU <barry.n1eu at gmail.com> wrote:
>> Does anybody have the information that was contained in the post that
>> W4PA mentions below? That link doesn't work any longer.
>>
>> Thanks & 73,
>> Barry N1EU
>>
>> ---------------------------------------------------------------------
>>
>> [CQ-Contest] Re: Omni-VI QSK with Alpha 87A
>> from [Ten-Tec, Inc. Amateur Radio Sales]
>> Subject: [CQ-Contest] Re: Omni-VI QSK with Alpha 87A
>> From: sales at tentec.com (Ten-Tec, Inc. Amateur Radio Sales)
>> Date: Wed Apr 7 12:02:46 1999
>>
>> Hi John W0UN (and all):
>>
>> The Omni-VI and Omni-VI Plus will run QSK CW very nicely with
>> the Alpha 87A. The normally open relay jack that is used for
>> keying an external linear amplifier in the Omni-VI was designed
>> for non-QSK amplifier use and isn't really optimal for QSK.
>>
>> Rather than repeat what's been posted elsewhere before, do a
>> browser point to:
>>
>> <http://www.contesting.com/_tentec/9809/0383.html>
>>
>> This very simple hookup uses a pickoff on the Omni-VI QSK
>> keying loop through a diode to the Alpha 87A input that will
>> provide both with smooth QSK keying.
>>
>> 73,
>> Scott Robbins, W4PA
>> Amateur Radio Product Manager, Ten-Tec, Inc.
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