[FoxHunt] HTX-202 Audio S-Meter Mod

Thu, 6 Jun 2002 12:53:10 -0700

Quite right, I use the signal on pin 13 of the MC3372 chip... the pdf data
sheet shows a graph of the signal on this pin vs RF input signal.

 As Marv says, I use it to drive a feedback loop in a polar plot display DF
:

www.silcom.com/~pelican2

And it works nicely...

----- Original Message -----
From: "Jess Hancock" <[email protected]>
To: <[email protected]>
Sent: Thursday, June 06, 2002 9:41 AM
Subject: Re: [FoxHunt] HTX-202 Audio S-Meter Mod

> IC4 is a Motorola mc3372 IF strip.  Check the link:
>
> http://pubpages.unh.edu/~aperkins/pdf/mc3372.pdf
>
> Pin 13 is labeled Meter Drive and in one of the diagrams is labeled RSSI
> Output which I believe is the S-Meter output of the chip.  In the HT
> schematic this is connected back to pin 10, Filter Input.  Filter output,
> pin 11 appears to be DC coupled and drives a line labeled SGL.  The
junction
> of R33 and R34 might be a possible S-meter dc voltage pickoff point.
>
> Let me know.
>
> 73, Jess, w4pqk
>
>
> -----Original Message-----
> From: Marvin Johnston <[email protected]>
> To: [email protected] <[email protected]>
> Date: Thursday, June 06, 2002 11:34 AM
> Subject: Re: [FoxHunt] HTX-202 Audio S-Meter Mod
>
>
> >
> >Bob Simmons, WB6EYV, taps into the HTX-202 S meter circuit to use the
> >HTX-202 with his Yagi Plot setup. I checked his website
> >(http://www.silcom.com/~pelican2/) but didn't see any mention of the
> >mods. He does read this list, and can probably answer the question.
> >
> >Marvin, KE6HTS
> >
> >Dennis Boone wrote:
> >>
> >> As an electronic technician, I'm not a bad computer sysadmin, but I
> >> went looking for such a point a few years ago for exactly the same
> >> reason.  My fuzzy memory seems to recall that the only place s-meter
> >> intelligence was available outside of an IC was in a form suitable for
> >> driving a display, e.g. bcd, serial, or some such.  I'd love to be
> >> proven incompetent on this one, though.
> >>
> >> Dennis Boone
> >> KB8ZQZ
> >>
> >>  > I know a ham that claims to have done most of the factory service
work
> >>  > on the 202 for RS.  I posed the same question him a few years ago
and
> he
> >>  > could not come up with a point.  He seemed to be sincere  but you
> never
> >>  > know.  The tight front end would make it a great fox hunting rig.
> >>  > Please post the information if you find a mod.
> >>
> >>  >  > Has anyone ever tried to find a point on the Radio Shack
> >>  >  > HTX-202 HT PCB to tap off the voltage/signal from the
> >>  >  > S-meter display circuit chain?  I'd like to see if I can add
> >>  >  > a voltage driven osc for a audio S-meter to a -202.
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>
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