[TenTec] Paragon pin diodes

[Chester Alderman]

It could be that the only thing you may miss out on is the frustration of having them blow if  they are used for antenna switching and you load your rig into a high SWR. A PIN diode is a silicon device that is doped specifically to be able to switch states (ON/OFF) very rapidly; by very rapidly, I mean nanoseconds as compared to a relay which normally switches in milliseconds. PIN diodes do switch fast, and they do have typically a high forward voltage that they will withstand before the blow out. But also, typically, they do not have a high reverse voltage. Therefore they will blow out easily when you load your xmtr into a high SWR and you have a high voltage reflection back into your radio. 

PIN diodes are also used for low-level switching circuits, such as switching filters in a rig. The designer must be careful in how they are biased (and TenTec does this well) so there is enough forward current flowing through them to reduce the diodes tendancy toward generating intermod distortion.

Two ways you can find out if you have PIN diodes. 1) Read the manual! 2) Determine the part number of the diode, and look it up in a semiconductor reference book to determine what type diode it is. Typically, but not always, PIN diodes are used in the more modern rigs for switching filters within the rig; some, but not all, rigs do use PIN diodes for T/R switching of the antenna between the receiver and the xmtr.

Generally, if your rig has a reed or vacuum relay for T/R switching, your rig will still switch very fast, fast enough for you to run full QSK (break-in) at code speeds up to 80-100 wpm. If you need a rig that will switch faster, then you should look at different rigs specifications and buy one using PIN diodes for T/R switching. The difference (basic) between a relay and a PIN diode is the PIN switches faster and of course is significantly smaller than a relay. The tradeoff is a relay does not generate intermod, and a PIN diode can.




At 03:43 PM 9/16/97 -0400, you wrote:

>What is the story on these pin diodes? How do I know

>whether my Paragon has them? Am I missing out on

>something?

>

>73, Ed WX4S

>

>

><< I have a TenTec Paragon model 585 for sale. It is a 91 model and is in 

><< excellent condition (9+). This radio comes with TenTec and Giehl Chips, 

><< the 961 Power supply, 705 desk mike and has the Pin diodes installed in 

><< the receiver circuit. I have original boxes and manuals Tentec gets 

>

>

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Chester Alderman

<color><param>0000,0000,ffff</param>W4BQF -- Tom

</color><color><param>ffff,0000,0000</param>chestert@pressroom.com

</color>


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