"Fred McKenzie" wrote in message
...
I used my HTX-252 for the first time last weekend, and was
told that the audio was muffled although intelligible. Anyone know of a
cure
for this muffled effect?
Cal-
I also have one of the bargain HTX-252 transceivers. I had read here
about the
low audio and expected that would be a problem for me as well.
What I found was that the radio has no microphone gain adjustment, just a
peak
deviation adjustment, as has been discussed here. Checking modulation, I
found
that it was working well with no further adjustment needed. It is just
set up
to REQUIRE close talking to the microphone, and some people prefer to hold
it
several inches away. The microphone element is located at the top front
of the
microphone, so holding that spot within an inch of your mouth should give
good
modulation without having to shout. During my testing I tried a couple
other
similar microphone elements with no increase in sensitivity.
The only reason I can think of that would cause muffled audio, would be if
someone had gone into either the microphone or the transceiver's
microphone
amplifier circuits, and tried to "fix" it! If you recently purchased
yours and
it was the last one in the store, it is possible that it had been returned
by a
previous customer. As such, it might have a factory defect, or it might
have
been returned because of the failed attempt at improving it. Either way,
your
best bet may be to take it back to a Radio Shack store along with the
receipt,
and have them send it in for repair. I believe their technicians have
seen
most of the problems many times, and should make fast work of a repair.
Per someone's suggestion here, I found service information for the
Albrecht
AE-540 at http://www.albrecht-electronic.de/se...eurfunk/AE540/
which
appears to be almost exactly the same as the HTX-252. Following the
microphone
audio path, there is a 2200 Ohm resistor that leads to the push-to-talk
circuit. That circuit is AC coupled by a 0.1 microfarad capacitor, to
another
2200 Ohm resister, that connects to the audio processor integrated
circuit. I
believe some increase in microphone gain would be achieved if that second
2200
Ohm resistor were shorted. However, the frequency response might also be
affected. As a wild guess, I would look on the bottom side of the main
circuit
board for that 2200 Ohm resistor. It is located near a shield as I
recall. If
you find it has been shorted, try un-shorting it and see if the audio
improves.
By the way, I also checked www.mods.dk and found a suggestion to remove a
certain one microfarad capacitor to speed-up the radio's squelch response.
I
decided that it was a better idea to replace it with a 0.1 microfarad
capacitor. As far as I can tell, that is the only worthwhile modification
the
radio needs.
73, Fred, K4DII
Thanks for the tips on the 252... I'll store them for future use. I bought 2
of them brand new, never had them out of the box yet. I had set them aside
awaiting to use them for a project, then found they weren't able to be used
for it. Now too late to return them, as it was past 30 days. ALL have
extended warranty. If anyone should be interested in one of them or both,
I'll sell em for what I got in them plus shipping.
L.