Xref: utzoo rec.ham-radio:5311 sci.electronics:3257 Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!ncar!oddjob!gargoyle!att!ihnp4!ihuxz!parnass From: parnass@ihuxz.ATT.COM (Bob Parnass, AJ9S) Newsgroups: rec.ham-radio,sci.electronics Subject: Re: More Mods for the PRO 2004 !! Summary: S-meter tip of limited utility Keywords: More Fun, TURBO, S Meter Message-ID: <3064@ihuxz.ATT.COM> Date: 9 Jul 88 04:15:56 GMT References: <1193@raybed2.UUCP> Organization: AT&T Bell Laboratories - Naperville, Illinois Lines: 34 About the Radio Shack PRO-2004 scanner, Gene Balinski WA1UXA, wrote: > ...But adding an "S" meter is even easier than previously thought. > Pin 10 on the IF amplifier is an "S" meter output. > With the proper bridge or meter buffer/amplifier an "S" meter > is reality.... > > Hopefully someone can/will verify that these mods > work. (Bob Parnass where are you???) Good Listening. Despite the internal IC block diagram in the service manual, WBFM IC pin 10 on my PRO-2004 is useful as an S-meter output only when the radio is in the WBFM mode. Between pin 10 and ground, I placed a 10,000 ohm resistor in series with a 250 microamp meter for a simple test setup. The meter read full scale on strong WBFM signals. With no signal at all, the meter read about 70% of full scale. One could add a bridge, but this metering point is of limi- ted utility. COR lights are handy as visual cues in a room filled with operating scanners. Pin 13 on the NBFM IC is a good pickoff point for triggering a COR light. I applied the signal on pin 13 through a 10,000 ohm resistor to the base of an NPN transistor switch to actuate an LED when a carrier is present. -- ===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-=== Bob Parnass AJ9S, AT&T Bell Laboratories - att!ihuxz!parnass - (312)979-5414