HTX-202

[KI4YJS / Scott]

I went on vacation last week to Disney World and I packed up my ht to
take with me. When I got there I unpacked it and turned it on and to
my surprise I had very very little audio. This is with the volume at
max and with the squelch off. I also checked it with an external
speaker and it has very low audio as well. The unit will transmit and
receive great...just has very low audio. Has anyone ever had this
problem? If so how did you repair the problem or shall I say restore
the audio level to normal.

[Christopher Mills Wolfe]

If that's a Radio Shack "brick" go here:
http://www.eham.net/articles/11750

[Christopher Mills Wolfe]

Try this also, it's from the mods.dk web site:

Common problem with the HTX-202 is that using it with a TNC requires the
volume be turned WAY up. With the squelch open it does not take long to
burn out the audio amp. There's an easy fix.

Open it up:

Remove the antenna, battery pack, and anything else you have hooked up to
the radio.

Remove 5 screws on the back and the 4 screws on the battery plate.

Pull the back away from the radio, taking care not to break the ribbon
cable that connects the to sides.

Find the audio sub board. This is on the main board just below the large
removable connector at the top of the radio.

Unplug this big wire connector from the top.

Flip the radio over and find the 6 pins for the audio sub board.

Break out the soldering iron and push the pins out from the back while
giving a pull on the board from the front. Be careful not to damage the
pins or get solder on any of the other parts. "that would be bad".

Now you have two options.
Option 1: Replace the entire audio board with another from a dead HTX-202
or an HTX-404. Option 2: Replace the IC on the audio board (IC601) with
an LM386N-3 LOW VOLTAGE AUDIO AMP.

Replace the audio board in it's place making very sure to only use just
enough solder to connect it, watch those connections, lots of other pads
on the back that are very close to the audio board's pins.

Plug in the wire connector.

Put it all back together.

:~) N5VJA

"To prevent this problem,
The HTX-202 requires a modification on the audio output board.

A 10 Ohms 1/4W resistor MUST be added in series with C603.

When output is loaded with way-too-high impedance load, The amplifier IC
is prone to high frequency oscillation (ultrasonic or higher).
If the IC start to oscillate, C603 apears to IC601 as a dead-short,
causing IC601 to blow.

A 10 Ohms resistor in series with C603 forms a dummy-load to prevent high
frequency oscillation.

Take your time! Unsoldering the audio PCB and IC601 can be tough if
you're not familiar with bouble-sided PCB and surface-mounted componants!

Thanks to VE2TUB for this part"