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Re: [TenTec] Can I use the TT 670 Keyer ...

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Can I use the TT 670 Keyer ...
From: Ken Brown <ken.d.brown@hawaiiantel.net>
Reply-to: ken.d.brown@hawaiiantel.net,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 29 Oct 2007 09:21:18 -1000
List-post: <mailto:tentec@contesting.com>
Hi Karl,

Most keyers I have ever heard about are designed to switch the keying 
lead of the transmitter (or transceiver) to ground, so they are 
compatible with any rig (careful, read below) that can also use a 
straight key or bug. Straight keys and bugs are purely mechanical 
devices that provide a simple contact closure. Almost always, one side 
of the key is grounded and the other lead, which is connected to the 
keying input of the transmitter, is connected to ground when the key 
contacts are closed. Electronic keyers were originally designed to plug 
into the same keying input jack as a straight key. Bugs often had a 
wedge connector that could be inserted between the open contacts of a 
straight key. In any case, the point is that most keyers switch a keying 
lead to ground, and most transmitters have a keying lead that activates 
the transmitter when grounded.
Where you need to be careful is with older tube equipment which may have 
hundreds of volts on it's keying lead. Some electronic keyers are 
designed to work with this and some are not. Often newer electronic 
keyers will have an output device (transistor or IC) with a voltage 
rating such that it will be fried by connecting it to an older tube rig. 
Some tube rigs may also have a negative voltage on the keying lead, 
which needs to be pulled to ground to key it (most solid state rigs will 
have a positive voltage), so even if the output device of the keyer 
could handle the voltage, it would not conduct in that direction. 
Therefore many keyers have jumpers that can be configured to work with 
either polarity, or they have two separate output connectors for keying 
either a positive or negative voltage keying input.

Ten-Tec made some tube transmitters long ago. I suspect however that the 
670 key was designed to work with ANY solid state Ten-Tec transceiver, 
except perhaps their older tube products (which are fairly rare I believe).

If connecting the keyer to your Omni C shuts the rig down, there is 
either something wrong with the keyer or something wrong with the way 
you have connected it.
Does a plain straight key shut down the rig when connected and keyed? 
Maybe someone has already fried the output transistor on the keyer. In 
that case I would expect it either to not work at all, or to key the rig 
continuously, but not to shut it down. There is something wrong with 
this picture.

DE N6KB


Karl Schwab wrote:
> Gentlemen; I have a Ten-Tec 670 Keyer that appears to
> be designed for only use with the Century 21
> transceiver.  I tried it on my Omni "C" series
> transceiver, and it immediately shut the transceiver
> down!  So, it guess it will not work on this
> transceiver, but I am wondering if it might work on my
> Argonaut 509 transceiver?  Anyone know?  I'm afraid to
> try it!  If I can't use it, I'll consider trading for
> another keyer or selling this one.  Thanks for your
> comments, de KO8S
>
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