home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
QRZ! Ham Radio 21
/
QRZ Ham Radio Callsign Database - Volume 21.iso
/
MODFILES
/
HTX202PK.TXT
< prev
next >
Wrap
Text File
|
2001-11-06
|
1KB
|
34 lines
Subject: Subj: HTX-252 Packet
This radio wasn't particularly suited to packet use as purchased.
Transmit was easily decoded by other rigs, but receive audio was, shall
we say, horrible. Looking at the audio signal it appeared that the
1200Hz tone had about 6-12dB more gain than the 2200Hz tone when
working 1200 AFSK.
To solve this, route the rx signal directly from the FM detector
directly to the 1/8" speaker jack. The audio signal has a DC componant
that is blocked by a 470uF/16V electrolytic (radial leaded tubular
located near the side of the chassis near the speaker jack).
Remove the 470uF cap and use one pad to route the rx signal from the
FM detector (TK10487 pin 11) through a small cap (there is a DC bias on
pin 11) to the pad connected to the speaker jack. I used a .015 from
the junk box as it was small enought to fit between the PCB and the
cover.
The audio can also be reconnected using a axial leaded cap (+ to PCB)
in the remaining pad (signal from the audio amplifier) to provide audio
to the speaker (probably the brown wire, other side is connected to
ground).
Speaker now works, volume/squelch do con control the signal to the
speaker jack, it is line-level at about 800mV for a packet signal.
Note that the jack is unsquelch-ed, so newer TNC's only...
regards
-Willy
KC0JFQ