

Article 15468 of rec.ham-radio:
Path: philabs!prls!pyramid!decwrl!ucbvax!minster.york.ac.UK!fisher
>From: [email-masked]
Newsgroups: rec.ham-radio
Subject: MODIFICATION for BC 100 for AM/FM on all freqs.
Message-ID: <[email-masked]>
Date: 31 Oct 89 19:50:56 GMT
Sender: [email-masked]
Organization: The Internet
Lines: 38

The Uniden Bearcat 100 XL is a beautifully made receiver which covers 66 - 512
MHz (with gaps).  It can receive both AM and FM signals, but you cannot
select which you want:  the receiver selects AM on the air band (118 - 136 MHz)
and FM everywhere else.  The following simple modification will allow you to
select AM or FM independently of the frequency, by means of a 3-position
switch.  The three settings are:  AM; FM; auto. (viz. AM on the air band, FM
everywhere else).

Remove the battery cover.  Unplug the ribbon cable at the bottom end of the
receiver, and pull out the microprocessor (uP) board, which is also the front
panel.  Label the 12 wires of the ribbon cable 1 to 12, starting from the
left, with the component side of the uP board towards you.  Wire 2 is Vcc
(about 7 V), wire 12 is ground, and wire 8 is the signal which goes from the
uP to the receiver board to select AM or FM operation.  It is 0 V (or open)
for FM, and Vcc (approx.) for AM.

Unsolder wire 8 from the board, removing excess solder with a solder-sucker
or wick.  Obtain a single-pole change-over toggle switch with centre "off",
and connect as follows.

	from wire 8 on uP board       ______@
					   @---@_____ to wire 8 on Rx board
	from wire 2 on uP board (Vcc) ______@             (AM/FM select)

Use heat-shrink sleeving or plastic tape to insulate the connections.

The switch can be mounted on the battery cover, or perhaps -- if you can find
a small enough switch -- on the top panel, next to the "lock" switch.

I've done it and it works.

----
Tony Fisher
Dept. of Computer Science, The University of York, York YO1 5DD, U.K.
Tel. +44 904 432738 or 432722
Janet:  [email-masked]
DARPA:  fisher%uk.ac.york.minster@ucl-cs
UUCP:   [email-masked] (..!uunet!mcvax!reading!minster!fisher)