Dec 232017
Various modifications for the Radio Shack Pro-43 scanner.
File PRO43MOD.ZIP from The Programmer’s Corner in
Category Miscellaneous Language Source Code
Various modifications for the Radio Shack Pro-43 scanner.
File Name File Size Zip Size Zip Type
P43SMETR.TXT 4771 1945 deflated
PRO43AUD.TXT 2375 1214 deflated
PRO43BEP.MOD 924 444 deflated
PRO43INF.MOD 9559 4268 deflated
PRO43MOD.TXT 3712 1470 deflated

Download File PRO43MOD.ZIP Here

Contents of the P43SMETR.TXT file

[8] Radio Technology (500:10/12.1) RADIO_TEK
Msg : #3305 [157] Uns Loc
From : Bill Cheek 1:202/731.1 Sat 06 Feb 93 00:24
To : All
Subj : PRO-43 S-Meter!

.MSGID: 1:202/731.1 2b73580c
Greetings Scanner Fans!

It had to happen! The fundamentals for an S-Meter exist alive and well in the
PRO-43! Only a simple circuit and your choice of meter, analog or LED, is
required for a jim-dandy S-Meter function!

The key point in the circuit is the cathode of D-302 located on the bottom
(solder side) of the AF Board (middle board). You will need the Service Manual
for the PRO-43 to find it as it's not marked and it would take me 10,000 words
to guide you to exactly where it is located. Call Tandy National Parts at (800)
442-2425 to order your manual: approx $10. Now here is the deal:

Locate D-302 and either build the following circuit right there on the back of
the AF board in the vicinity of D-302, or solder a wire to the cathode of D-302
and route it to somewhere else more convenient to feed the below circuit. This
wire ought not to be very long, though, say not more than a couple of inches.
Refer to the ASCII schematic diagram as follows:

PRO-43 D-302 existing
T-302 x---o--|<-------x PRO-43 ckt
/ |
Connect |
here | 0.01-uF 1N34A
|------||------o-------->|----o---o-----------> (+)
| | |
| \ | To the
| 47-k / | S-Meter of
| ohms \ = 0.01-uF Your Choice
| / | (This should
| 1N34A | | be a jack
|-----|<-------o---o----------> (-) mounted on
^ PRO-43 Ground^ the case of
Legend: the scanner.
1. ---||--- and = are 0.01-uF capacitors; disk, mylar, monolythic, chip

2. --->|--- and ---|<---- are germanium diodes, 1N34A
| is cathode
< is anode

3. o means a connection, preferably soldered

4. The 47-k resistor is self-explanatory, I hope.

5. -------- and | are wires/conductors.

6. x is existing PRO-43 circuitry

If you use an analog meter, preferably a real S-Meter like salvaged from an old
junked CB rig, then rig it as follows to connect to the circuit above:

5-k Trim Pot
(+) --------/\/\/\/\---o--------|
| | |
This should |-------| |
be a plug of +
some sort to The S-Meter
connect to the Terminals
mating jack on -
the scanner |

You can also build the 10-segment LED S-Meter as shown in Volume 2 of
my SCANNER MODIFICATION HANDBOOK, available from leading mail order
radio dealers everywhere. ISBN 0-939780-14-3 published by CRB Research Books,
Inc. Commack, NY.

After connected and working, locate the PRO-43 very near a known strong
transmitter, perhaps a ham transmitter, a police cruiser, your favorite security
guard's handheld or right next to a cordless telephone, or anything else known
to transmit a strong signal. Tune the scanner to the frequency, and adjust the
5-k trim pot above so the meter reads exactly full scale. All other signals
will read proportionally lower to yield "relative signal strength" measurements!
A hell of a circuit here, boys & girls! Have fun!

Developed & distributed by: Bill Cheek
COMMtronics Engineering
PO Box 262478
San Diego, CA 92196-2478

Ok to distribute, but credit appreciated. Thanks!

Bill Cheek

--- GoldED 2.41.B0108+
* Origin: Hertzian Intercept, San Diego (6pm-1pm) 619-578-9247 (1:202/731.1)

 December 23, 2017  Add comments

 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>