Has there been a modern rig that used pin diodes for TR switching? All
the TenTec's I've been in to have used a reed relay with the exception
of the Scout and the QRP series. I didn't have the Scout long enough to
find out anything.
Also, the switching diodes used for band switching in the Paragon get
hot. Yes, try holding your finger on one for a while!
Chester Alderman wrote:
> 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
> 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
> >73, Ed WX4S
> >< I have a TenTec Paragon model 585 for sale. It is a 91 model and is
> >< excellent condition (9+). This radio comes with TenTec and Giehl
> >< 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
> W4BQF -- Tom
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