[Pro2006] 2006 IF bandwidth Mod?

[email protected] [email protected]
Tue, 17 Sep 2002 21:23:29 -0500


I found this in my old files. It's from the Guru himself. May he rest in
peace...


Danno
Hockley, TX
KD5CEU



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Modifying the Pro-2006 for weather imagery

 
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>From wxsat![email protected] Wed Feb  5 17:47:35 1997
To: [email protected]
Subject: Here is how you modify the Pro-2006 for weather imagery
From: [email protected] (wxsat mailer)
Reply-To: [email protected]
Original-Sender: Matthew Veit
Message-Id: <[email protected]>
Date: Wed, 05 Feb 97  04:47:01 UTC
Organization: System Support Group

# The following is forwarded by the wxsat mail list daemon.
# Mail addressed to wxsat-mail-daemon@ssg will be discarded.
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Subject: Here is how you modify the Pro-2006 for weather imagery
From: Matthew Veit
Date: Tue, 04 Feb 1997 19:54:12 -0800

Hi everyone,
Here is your needed info:
Here is my reply from Bill Cheek, the world's greatest authority on the
2006....

January 28, 1997

Reply from Bill Cheek ([email protected]) (c) 1997

DT> I'm trying to find out about bypassing the filter on a Pro 2006 for
use
DT> with APT Wefax, no luck.

DT> Could you please briefly tell me the filter's part number, how to
DT> install the capacitor? I'd really appreciate it. I'll share the info
DT> with the wefax mailing list.

Depends.  Most guys use the NFM mode.  The selectivity of the
NFM section of the receiver is primarily set by a 455 kHz ceramic
IF filter that's connected to the NFM Discriminator chip between
a couple of close or adjacent pins.  The selectivity of this filter
is typically +/- 7.5 kHz or 15 kHz wide.  At best, it is a compromise
because it's too wide for 5kHz and 10kHz channels; about right for
12.5 kHz and 25 kHz channels, and much too narrow for 30 kHz/up
channels like computer data including WEFAX.

Baud rates of 9600-bps pretty much require an IF bandwidth of
20 kHz, minimum.... with 50 kHz required for 14.4-kbps.  Therefore
the WEFAX and computer data aficionado has little choice but to
modify the IF selectivity for those signals.  You certainly can
"bypass" the resident IF filter with a capacitor of a certain value,
though the best option is to replace the stock IF filter with a
wider one.  Apparently wider IF filters are not all that easy to
come by, so the capacitor bypass is an attractive option.

First find the IF filter and the NFM Discriminator chip:

Selected radios:
=================================
PRO-2004:  CF2 at IC2, pins 3 & 5
PRO-2005:  CF4 at IC2, pins 3 & 5
PRO-2006:  CF4 at IC2, pins 3 & 5
PRO-2035:  CF3 at IC2, pins 3 & 5
PRO-2042:  CF3 at IC2, pins 3 & 5

Short of a 30 kHz replacement filter, I'd suggest soldering
a pinline socket to each of the two NFM chip/filter pins, and
then plug in a range of ceramic disk capacitors until you find
one that works best.  You can easily remove the capacitor with
no ill effects to return to normal operation.

Values to try include:

47-pF. 100-pF, 470-pF .001-uF   .01-uF

The idea is to leak just enough of the desired signal around
the IF filter.  Too much, and adjacent channel interference looms as
a show stopper.  Too little, and you're back to Square One.

Pinline sockets are highly recommended.  You can break apart
one pin from the strip; solder it to a pin of the IC, and it
becomes just like a professional test point with no destructive
effects.  Leave it there permanently.

To solder the pinline socket to the IC pin, first remove all the
plastic insulation from the pin so that it is bare metal.  Insert
a sewing needle into the female socket of the pinline (as a holder)
and coat the male plug part of the pinline with solder.  Then
pre-solder the pin of the IC.  Then place the pinline's male part
up to the IC pin with the sewing needle still in the socket as a
"holder"....position it straight and perfectly against the IC pin,
and touch-dab with the soldering pencil one last time.  Voila!

Most component leads will insert into a pinline socket just like
a plug....good fit....but for those larger leads that won't fit,
just solder the female ends of a pair of pinlines to the component's
shortened and prepared (length) leads and plug the male ends into
the female pinlines on the IC chip.

There is no danger to the chip for reasonable contact periods and
reasonable heat.  Pinline sockets mean just one soldering job to
the IC and then you're forever done because a variety of things
can be plugged in after that.....no soldering!  Pinline sockets come
in strips of up to 32 pins per strip.  All are "break apart" in that
you break off or cut however many you want.  They're kind of expensive
but no hacker should be without them.  A good starter quantity for the
occasional hacker would be around 100-pins or so.  Sources and data
for Pinline sockets are as follows:

Digikey:  (800) 344-4539   p/n:  A208-ND
Mouser:   (800) 346-6873   p/n:  151-5530
Hosfelt:  (800) 524-6464   p/n:  21-274

(c) 1997 Bill Cheek
+----------------------------------------------------------------------+
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+----------------------------------------------------------------------+

---------------------------------------------------
Dishheads, dishheads, Roly poly dishheads!
May all of your clothes be covered with cat hair!
---------------------------------------------------

--------------------------- End Of Message
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I hope that this helps you all.
-Matt

--------------------------- End Of Message
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On Mon, 16 Sep 2002 19:52:14 -0400 radionut <[email protected]>
writes:
> 
> A long time ago, I ran into a modification for the 2006 to set the 
> wide band
> mode selection to 42 KHz for weather satellite reception. 
> 
> I have been searching and can not find a web link to the 
> information. A
> couple links that look like they may have it are dead and gone.
> 
> Can anyone let me know where I can find this modification?
> _______________________________________________
> Pro2006 mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/pro2006
> 


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